MaxCompute SQL provides common mathematical functions that you can use for development. You can select mathematical functions based on your business requirements for data computing and data type conversions. This topic describes the syntax, parameters, and examples of mathematical functions supported by MaxCompute SQL.

Function | Description |
---|---|

ABS | Calculates the absolute value. |

ACOS | Calculates the arccosine. |

ASIN | Calculates the arcsine. |

ATAN | Calculates the arctangent. |

CEIL | Rounds up a number and returns the nearest integer. |

CONV | Converts a number from one number system to another. |

COS | Calculates the cosine. |

COSH | Calculates the hyperbolic cosine. |

COT | Calculates the cotangent. |

EXP | Calculates the exponential value. |

FLOOR | Rounds down a number and returns the nearest integer. |

LN | Calculates the natural logarithm. |

LOG | Calculates the logarithm. |

POW | Calculates the nth power of a value. |

RAND | Returns a random number. |

ROUND | Returns a value rounded to the specified decimal place. |

SIN | Calculates the sine. |

SINH | Calculates the hyperbolic sine. |

SQRT | Calculates the square root. |

TAN | Calculates the tangent. |

TANH | Calculates the hyperbolic tangent. |

TRUNC | Truncates the input value to the specified decimal place. |

BIN | Calculates the binary code. |

CBRT | Calculates the cube root. |

CORR | Calculates the Pearson correlation coefficient. |

DEGREES | Converts a radian value to a degree. |

E | Calculates the value of e. |

FACTORIAL | Calculates the factorial. |

FORMAT_NUMBER | Converts a number to a string in the specified format. |

HEX | Converts an integer or a string into a hexadecimal number. |

LOG2 | Calculates the logarithm of a number with the base number of 2. |

LOG10 | Calculates the logarithm of a number with the base number of 10. |

PI | Calculates the value of π. |

RADIANS | Converts a degree to a radian value. |

SIGN | Returns the sign of the input value. |

SHIFTLEFT | Shifts a value left by a specific number of places. |

SHIFTRIGHT | Shifts a value right by a specific number of places. |

SHIFTRIGHTUNSIGNED | Shifts an unsigned value right by a specific number of places. |

UNHEX | Converts a hexadecimal string to a string. |

WIDTH_BUCKET | Returns the ID of the bucket into which the value of a specific expression falls. |

## ABS

- Syntax
`double abs(double <number>) bigint abs(bigint <number>) decimal abs(decimal <number>)`

- Description
This function calculates the absolute value of number.

- Parameters
number: required.
**Note**If number is of the BIGINT type and is greater than the maximum value of the BIGINT type, a value of the DOUBLE type is returned. However, the precision may be lost. - Return value
The type of the return value depends on the type of the input parameter. If number is of the DOUBLE, BIGINT, or DECIMAL type, a value of the same type is returned.
- If number is of the BIGINT type, the return value is of the BIGINT type.
- If number is of the DOUBLE type, the return value is of the DOUBLE type.
- If number is of the DECIMAL type, the return value is of the DECIMAL type.
- If number is of the STRING type, it is implicitly converted into a value of the DOUBLE type before the calculation.
- If the input value is set to null, null is returned.
- If number is of a data type other than the preceding types, an error is returned.

- Examples
`-- The value null is returned. select abs(null); -- The value 1 is returned. select abs(-1); -- The value 1.2 is returned. select abs(-1.2); -- The value 2.0 is returned. select abs("-2"); -- The value 1.2232083745629837E32 is returned. select abs(122320837456298376592387456923748); -- Calculate the absolute value of the id field in tbl1. The following example shows the usage of an ABS function in SQL statements. Other built-in functions, except window functions and aggregate functions, are used in a similar way. select abs(id) from tbl1;`

## ACOS

- Syntax
`double acos(double <number>) decimal acos(decimal <number>)`

- Description
This function calculates the arccosine of number.

- Parameters
number: required. The value is of the DOUBLE or DECIMAL type and ranges from -1 to 1. If the input value is of the STRING or BIGINT type, it is implicitly converted into a value of the DOUBLE type before the calculation.

- Return value
A value of the DOUBLE or DECIMAL type is returned. The value ranges from 0 to π. The return value varies based on the following rules:
- If number is not of the DOUBLE, DECIMAL, STRING, or BIGINT type, an error is returned.
- If the value of number is null, null is returned.

- Examples
`-- The value 0.5155940062460905 is returned. select acos("0.87"); -- The value 1.5707963267948966 is returned. select acos(0); -- The value null is returned. select acos(null);`

## ASIN

- Syntax
`double asin(double <number>) decimal asin(decimal <number>)`

- Description
This function calculates the arcsine of number.

- Parameters
number: required. The value is of the DOUBLE or DECIMAL type and ranges from -1 to 1. If the input value is of the STRING or BIGINT type, it is implicitly converted into a value of the DOUBLE type before the calculation.

- Return value
A value of the DOUBLE or DECIMAL type is returned. The value ranges from -π/2 to π/2. The return value varies based on the following rules:
- If number is not of the DOUBLE, DECIMAL, STRING, or BIGINT type, an error is returned.
- If the value of number is null, null is returned.

- Examples
`-- The value 1.5707963267948966 is returned. select asin(1); -- The value -1.5707963267948966 is returned. select asin(-1); -- The value null is returned. select asin(null);`

## ATAN

- Syntax
`double atan(double <number>)`

- Description
This function calculates the arctangent of number.

- Parameters
number: required. The value is of the DOUBLE type. If the input value is of the STRING or BIGINT type, it is implicitly converted into a value of the DOUBLE type before the calculation.

- Return value
A value of the DOUBLE type is returned. The value ranges from -π/2 to π/2. The return value varies based on the following rules:
- If number is not of the DOUBLE, STRING, or BIGINT type, an error is returned.
- If the value of number is null, null is returned.

- Examples
`-- The value 0.7853981633974483 is returned. select atan(1); -- The value -0.7853981633974483 is returned. select atan(-1); -- The value null is returned. select atan(null);`

## CEIL

- Syntax
`bigint ceil(double <value>) bigint ceil(decimal <value>)`

- Description
This function rounds up value and returns the nearest integer.

- Parameters
value: required. The value is of the DOUBLE or DECIMAL type. If the input value is of the STRING or BIGINT type, it is implicitly converted into a value of the DOUBLE type before the calculation.

- Return value
A value of the BIGINT type is returned. The return value varies based on the following rules:
- If number is not of the DOUBLE, DECIMAL, STRING, or BIGINT type, an error is returned.
- If the value of number is null, null is returned.

- Examples
`-- The value 2 is returned. select ceil(1.1); -- The value -1 is returned. select ceil(-1.1); -- The value null is returned. select ceil(null);`

## CONV

- Syntax
`string conv(string <input>, bigint <from_base>, bigint <to_base>)`

- Description
This function converts a number from one number system to another.

- Parameters
- input: required. The value is the integer you want to convert, which is of the STRING type. If the input value is of the BIGINT or DOUBLE type, it is implicitly converted into a value of the STRING type before the calculation.
- from_base and to_base: required. The values of these parameters are decimal numbers. The values can be 2, 8, 10, or 16. If the input value is of the STRING or DOUBLE type, it is implicitly converted into a value of the BIGINT type before the calculation.

- Return value
A value of the STRING type is returned. The return value varies based on the following rules:
- If the value of input, from_base, or to_base is null, null is returned.
- The conversion process runs at 64-bit precision. If an overflow occurs, an error is returned.
- If the value of input is a negative value, an error is returned. If the input value is a decimal, it is converted into an integer before the conversion of number systems. The decimal part is left out.

- Examples
`-- The value 12 is returned. select conv('1100', 2, 10); -- The value C is returned. select conv('1100', 2, 16); -- The value 171 is returned. select conv('ab', 16, 10); -- The value AB is returned. select conv('ab', 16, 16); -- The value null is returned. select conv('1100', null, 10);`

## COS

- Syntax
`double cos(double <number>) decimal cos(decimal <number>)`

- Description
This function calculates the cosine of number, which is a radian value.

- Parameters
number: required. The value is of the DOUBLE or DECIMAL type. If the input value is of the STRING or BIGINT type, it is implicitly converted into a value of the DOUBLE type before the calculation.

- Return value
A value of the DOUBLE or DECIMAL type is returned. The return value varies based on the following rules:
- If number is not of the DOUBLE, DECIMAL, STRING, or BIGINT type, an error is returned.
- If the value of number is null, null is returned.

- Examples
`-- The value 2.6794896585028633e-8 is retuned. select cos(3.1415926/2); -- The value -0.9999999999999986 is returned. select cos(3.1415926); -- The value null is returned. select cos(null);`

## COSH

- Syntax
`double cosh(double <number>) decimal cosh(decimal <number>)`

- Description
This function calculates the hyperbolic cosine of number.

- Parameters
number: required. The value is of the DOUBLE or DECIMAL type. If the input value is of the STRING or BIGINT type, it is implicitly converted into a value of the DOUBLE type before the calculation.

- Return value
A value of the DOUBLE or DECIMAL type is returned. The return value varies based on the following rules:
- If number is not of the DOUBLE, DECIMAL, STRING, or BIGINT type, an error is returned.
- If the value of number is null, null is returned.

- Examples
`-- The value 2.5091784169949913 is returned. select cosh(3.1415926/2); -- The value null is returned. select cosh(null);`

## COT

- Syntax
`double cot(double <number>) decimal cot(decimal <number>)`

- Description
This function calculates the cotangent of number, which is a radian value.

- Parameters
number: required. The value is of the DOUBLE or DECIMAL type. If the input value is of the STRING or BIGINT type, it is implicitly converted into a value of the DOUBLE type before the calculation.

- Return value
A value of the DOUBLE or DECIMAL type is returned. The return value varies based on the following rules:
- If number is not of the DOUBLE, DECIMAL, STRING, or BIGINT type, an error is returned.
- If the value of number is null, null is returned.

- Examples
`-- The value 2.6794896585028643E-8 is returned. select cot(3.1415926/2); -- The value null is returned. select cot(null);`

## EXP

- Syntax
`double exp(double <number>) decimal exp(decimal <number>)`

- Description
This function calculates the exponential value of number.

- Parameters
- Return value
- If number is not of the DOUBLE, DECIMAL, STRING, or BIGINT type, an error is returned.
- If the value of number is null, null is returned.

- Examples
`-- The value 4.810477252069109 is returned. select exp(3.1415926/2); -- The value null is returned. select exp(null);`

## FLOOR

- Syntax
`bigint floor(double <number>) bigint floor(decimal <number>)`

- Description
This function rounds down number and returns the nearest integer that is no greater than the value of number.

- Parameters
- Return value
A value of the BIGINT type is returned. The return value varies based on the following rules:
- If number is not of the DOUBLE, DECIMAL, STRING, or BIGINT type, an error is returned.
- If the value of number is null, null is returned.

- Examples
`-- The value 1 is returned. select floor(1.2); -- The value 0 is returned. select floor(0.1); -- The value -2 is returned. select floor(-1.2); -- The value -1 is returned. select floor(-0.1); -- The value 0 is returned. select floor(0.0); -- The value 0 is returned. select floor(-0.0); -- The value null is returned. select floor(null);`

## LN

- Syntax
`double ln(double <number>) decimal ln(decimal <number>)`

- Description
This function calculates the natural logarithm of number.

- Parameters
- Return value
A value of the DOUBLE or DECIMAL type is returned. The return value varies based on the following rules:
- If number is not of the DOUBLE, DECIMAL, STRING, or BIGINT type, an error is returned.
- If the value of number is a negative value or 0, an error is returned.
- If the value of number is null, null is returned.

- Examples
`-- The value 1.144729868791239 is returned. select ln(3.1415926); -- The value null is returned. select ln(null);`

## LOG

- Syntax
`double log(double <base>, double <x>) double log(decimal <base>, decimal <x>)`

- Description
This function calculates the logarithm of x whose base number is base.

- Parameters
- base: required. The value is of the DOUBLE or DECIMAL type. If the input value is of the STRING or BIGINT type, it is implicitly converted into a value of the DOUBLE type before the calculation.
- x: required. The value is of the DOUBLE or DECIMAL type. If the input value is of the STRING or BIGINT type, it is implicitly converted into a value of the DOUBLE type before the calculation.

- Return value
The logarithm value of the DOUBLE type is returned. The return value varies based on the following rules:
- If the value of base or x is null, null is returned.
- If the value of base or x is a negative value or 0, an error is returned.
- If the value of base is 1, an error is returned. The value 1 causes division by zero.

- Examples
`-- The value 4.0 is returned. select log(2, 16); -- The value null is returned. select log(2, null);`

## POW

- Syntax
`double pow(double <x>, double <y>) decimal pow(decimal <x>, decimal <y>)`

- Description
This function calculates the yth power of x, namely,

`x^y`

. - Parameters
- x: required. The value is of the DOUBLE or DECIMAL type. If the input value is of the STRING or BIGINT type, it is implicitly converted into a value of the DOUBLE type before the calculation.
- y: required. The value is of the DOUBLE or DECIMAL type. If the input value is of the STRING or BIGINT type, it is implicitly converted into a value of the DOUBLE type before the calculation.

- Return value
A value of the DOUBLE or DECIMAL type is returned. If the value of x or y is null, null is returned.

- Examples
`-- The value 65536.0 is returned. select pow(2, 16); -- The value null is returned. select pow(2, null);`

## RAND

- Syntax
`double rand(bigint <seed>)`

- Description
This function returns a random number of the DOUBLE type. The value ranges from 0 to 1.

- Parameters
seed: optional. The value is of the BIGINT type. This parameter specifies the random seed that determines the starting point in generating random numbers.

**Note**You can use seed to determine the random number sequence. After seed is determined, the return value of this function is fixed. - Return value
A value of the DOUBLE type is returned.

- Examples
`-- The value 4.7147460303803655E-4 is returned. select rand(); -- The value 0.7308781907032909 is returned. select rand(1);`

## ROUND

- Syntax
`double round(double <number>[, bigint <decimal_places>]) decimal round(decimal <number>[, bigint <decimal_places>])`

- Description
This function returns a number rounded to the specified decimal place.

- Parameters
- decimal_places: optional. The value is a constant of the BIGINT type. This parameter specifies the
decimal place to which the number is rounded. If this parameter is not specified,
the number is rounded to the ones place. The default value is 0.
**Note**The value of decimal_places can be negative. A negative value indicates counting from the decimal point to the left, and the decimal part is excluded. If decimal_places exceeds the length of the integer part, 0 is returned.

- Return value
A value of the DOUBLE or DECIMAL type is returned. The return value varies based on the following rules:
- If number is not of the DOUBLE, DECIMAL, STRING, or BIGINT type, an error is returned.
- If decimal_places is not of the BIGINT type, an error is returned.
- If the value of number or decimal_places is null, null is returned.

- Examples
`-- The value 125.0 is returned. select round(125.315); -- The value 125.3 is returned. select round(125.315, 1); -- The value 125.32 is returned. select round(125.315, 2); -- The value 125.315 is returned. select round(125.315, 3); -- The value -125.32 is returned. select round(-125.315, 2); -- The value 100.0 is returned. select round(123.345, -2); -- The value null is returned. select round(null); -- The value 123.345 is returned. select round(123.345, 4); -- The value 0.0 is returned. select round(123.345, -4);`

## SIN

- Syntax
`double sin(double <number>) decimal sin(decimal <number>)`

- Description
This function calculates the sine of number, which is a radian value.

- Parameters
- Return value
- If number is not of the DOUBLE, DECIMAL, STRING, or BIGINT type, an error is returned.
- If the value of number is null, null is returned.

- Examples
`-- The value -0.3048106211022167 is returned. select sin(60); -- The value null is returned. select sin(null);`

## SINH

- Syntax
`double sinh(double <number>) decimal sinh(decimal <number>)`

- Description
This function calculates the hyperbolic sine of number.

- Parameters
- Return value
- If number is not of the DOUBLE, DECIMAL, STRING, or BIGINT type, an error is returned.
- If the value of number is null, null is returned.

- Examples
`-- The value 5.343237290762231E12 is returned. select sinh(30); -- The value null is returned. select sinh(null);`

## SQRT

- Syntax
`double sqrt(double <number>) decimal sqrt(decimal <number>)`

- Description
This function calculates the square root of number.

- Parameters
number: required. The value is of the DOUBLE or DECIMAL type. The value must be greater than 0. If the value is less than 0, an error is returned. If the input value is of the STRING or BIGINT type, it is implicitly converted into a value of the DOUBLE type before the calculation.

- Return value
- If number is not of the DOUBLE, DECIMAL, STRING, or BIGINT type, an error is returned.
- If the value of number is null, null is returned.

- Examples
`-- The value 2.0 is returned. select sqrt(4); -- The value null is returned. select sqrt(null);`

## TAN

- Syntax
`double tan(double <number>) decimal tan(decimal <number>)`

- Description
This function calculates the tangent of number, which is a radian value.

- Parameters
- Return value
- If number is not of the DOUBLE, DECIMAL, STRING, or BIGINT type, an error is returned.
- If the value of number is null, null is returned.

- Examples
`-- The value -6.405331196646276 is returned. select tan(30); -- The value null is returned. select tan(null);`

## TANH

- Syntax
`double tanh(double <number>) decimal tanh(decimal <number>)`

- Description
This function calculates the hyperbolic tangent of number.

- Parameters
- Return value
- If number is not of the DOUBLE, DECIMAL, STRING, or BIGINT type, an error is returned.
- If the value of number is null, null is returned.

- Examples
`-- The value 1.0 is returned. select tanh(30); -- The value null is returned. select tanh(null);`

## TRUNC

- Syntax
`double trunc(double <number>[, bigint <decimal_places>]) decimal trunc(decimal <number>[, bigint <decimal_places>])`

- Description
This function truncates the input value of number to the specified decimal place.
**Note**If the Hive-compatible data type edition is used, this function is not a mathematical function. It is used to convert a date value. For more information about the related date function, see DATETRUNC. You must set the data type edition of your MaxCompute project based on your business requirements. For more information about data type editions, see Data type editions. - Parameters
- decimal_places: optional. The value is a constant of the BIGINT type. This parameter specifies the position where the number is truncated. If this parameter is not specified, the number is truncated to the ones place. decimal_places can be a negative value, which indicates that the number is truncated from the decimal point to the left and the decimal part is left out. If decimal_places exceeds the length of the integer part, 0 is returned.

- Return value
A value of the DOUBLE or DECIMAL type is returned. The return value varies based on the following rules:
- If number is not of the DOUBLE, DECIMAL, STRING, or BIGINT type, an error is returned.
- If decimal_places is not of the BIGINT type, an error is returned.
- If the value of number or decimal_places is null, null is returned.

**Note**- If a value of the DOUBLE type is returned, the return value may not be properly displayed.
This issue exists in all systems. For more information, see
`trunc(125.815,1)`

in the following examples. - The number is filled with zeros from the specified position.

- Examples
`-- The value 125.0 is returned. select trunc(125.815,0); -- The value 125.80000000000001 is returned. select trunc(125.815,1); -- The value 125.81 is returned. select trunc(125.815,2); -- The value 125.815 is returned. select trunc(125.815,3); -- The value -125.81 is returned. select trunc(-125.815,2); -- The value 120.0 is returned. select trunc(125.815,-1); -- The value 100.0 is returned. select trunc(125.815,-2); -- The value 0.0 is returned. select trunc(125.815,-3); -- The value 123.345 is returned. select trunc(123.345,4); -- The value 0.0 is returned. select trunc(123.345,-4); -- The value null is returned. select trunc(123.345,null);`

## Additional functions of MaxCompute V2.0

- Session level: To use the MaxCompute V2.0 data type edition, you must insert
`set odps.sql.type.system.odps2=true;`

before the SQL statement, and commit and execute them together. - Project level: The project owner can configure the MaxCompute V2.0 data type edition
for the project as required. It takes 10 to 15 minutes for the settings to take effect.
Run the following command:

For more information about`setproject odps.sql.type.system.odps2=true;`

`setproject`

, see Project operations. For the precautions you must take when you enable the MaxCompute V2.0 data type edition at the project level, see Data type editions.

## BIN

- Syntax
`string bin(bigint <number>)`

- Description
This function calculates the binary code of number. This function is an extension function of MaxCompute V2.0.

- Parameters
number: required. The value is of the BIGINT type.

- Return value
A value of the STRING type is returned. The return value varies based on the following rules:
- If number is not of the BIGINT type, an error is returned.
- If the value of number is 0, 0 is returned.
- If the value of number is null, null is returned.

- Examples
`-- The value 0 is returned. select bin(0); -- The value null is returned. select bin(null); -- The value 1100 is returned. select bin(12);`

## CBRT

- Syntax
`double cbrt(double <number>)`

- Description
This function calculates the cube root of number. This function is an extension function of MaxCompute V2.0.

- Parameters
number: required. The value is of the DOUBLE type.

- Return value
A value of the DOUBLE type is returned. The return value varies based on the following rules:
- If number is not of the DOUBLE type, an error is returned.
- If the value of number is null, null is returned.

- Examples
`-- The value 2.0 is returned. select cbrt(8); -- The value null is returned. select cbrt(null);`

## CORR

- Syntax
`double corr(<col1>, <col2>)`

- Description
This function calculates the Pearson correlation coefficient for two columns of data. This function is an extension function of MaxCompute V2.0.

- Parameters
col1 and col2: required. The names of the two columns for which the Pearson correlation coefficient is calculated. The DOUBLE, BIGINT, INT, SMALLINT, TINYINT, and DECIMAL types are supported. Data in the col1 and col2 columns can be of different data types.

- Return value
A value of the DOUBLE type is returned. If an input column has a null value in a row, the row is not involved in the calculation.

- Examples
A table contains two columns named a and b. The a column is of the INT type, and the b column is of the DOUBLE type. Data in the table:

You can run the following command to calculate the Pearson correlation coefficient for the columns:`+------------+------------+ | a | b | +------------+------------+ | 2 | 0.25 | | 1 | 0.5 | | 1 | NULL | +------------+------------+`

`-- The value -0.9999999999999999 is returned. select corr(a, b) from table;`

## DEGREES

- Syntax
`double degrees(double <number>) double degrees(decimal <number>)`

- Description
This function converts a radian value to a degree.

- Parameters
number: required. The value is of the DOUBLE or DECIMAL type. This function is an extension function of MaxCompute V2.0.

- Return value
A value of the DOUBLE type is returned. The return value varies based on the following rules:
- If number is not of the DOUBLE or DECIMAL type, an error is returned.
- If the value of number is null, null is returned.

- Examples
`-- The value 90.0 is returned. select degrees(1.5707963267948966); -- The value 0.0 is returned. select degrees(0); -- The value null is returned. select degrees(null);`

## E

- Syntax
`double e()`

- Description
This function calculates the value of

`e`

. This function is an extension function of MaxCompute V2.0. - Return value
A value of the DOUBLE type is returned.

- Examples
`-- The value 2.718281828459045 is returned. select e();`

## FACTORIAL

- Syntax
`bigint factorial(int <number>)`

- Description
This function calculates the factorial of number. This function is an extension function of MaxCompute V2.0.

- Parameters
number: required. The value is of the INT type and ranges from 0 to 20.

- Return value
A value of the BIGINT type is returned. The return value varies based on the following rules:
- If the value of number is 0, 1 is returned.
- If the value of number is null or a value that does not fall into the range from 0 to 20, null is returned.

- Examples
`-- The value 120 is returned. 5!=5*4*3*2*1=120 select factorial(5); -- The value 1 is returned. select factorial(0); -- The value null is returned. select factorial(null);`

## FORMAT_NUMBER

- Syntax
`string format_number(float|double|decimal <expr1>, <expr2>)`

- Description
This function converts a number to a string in the specified format. This function is an extension function of MaxCompute V2.0.

- Parameters
- expr1: required. This parameter specifies the expression that you want to format.
- expr2: required. This parameter specifies the format of the expression after the conversion.
It can be of the INT type to specify the number of decimal places. It can also be
expressed in a format similar to
`#,###,###.##`

.

- Return value
A value of the STRING type is returned. The return value varies based on the following rules:
- If expr2 is greater than 0, the value is rounded to the specified place after the decimal point.
- If expr2 is equal to 0, the value has no decimal point or decimal part.
- If expr2 is less than 0 or greater than 340, an error is returned.
- If the value of expr1 or expr2 is null, null is returned.

- Examples
`-- The value 5.230 is returned. select format_number(5.230134523424545456,3); -- The value 12,332.123 is returned. select format_number(12332.123456, '#,###,###,###.###'); -- The value null is returned. select format_number(null,3);`

## HEX

- Syntax
`string hex(bigint <number>) string hex(string <number>) string hex(binary <number>)`

- Description
This function converts an integer or a string to a hexadecimal number. This function is an extension function of MaxCompute V2.0.

- Parameters
number: required. If number is of the BIGINT type, a hexadecimal number is returned. If number is of the STRING type, a string in the hexadecimal format is returned.

- Return value
A value of the STRING type is returned. The return value varies based on the following rules:

- If the value of number is not 0 or null, a value of the STRING type is returned.
- If the value of number is 0, 0 is returned.
- If the value of number is null, an error is returned.

- Examples
`-- The value 0 is returned. select hex(0); -- The value 616263 is returned. select hex('abc'); -- The value 11 is returned. select hex(17); -- The value 3137 is returned. select hex('17'); -- An error is returned. select hex(null);`

## LOG2

- Syntax
`double log2(double <number>) double log2(decimal <number>)`

- Description
This function calculates the logarithm of number with the base number of 2. This function is an extension function of MaxCompute V2.0.

- Parameters
number: required. The value is of the DOUBLE or DECIMAL type.

- Return value
A value of the DOUBLE type is returned. The return value varies based on the following rules:
- If number is not of the DOUBLE or DECIMAL type, null is returned.
- If the value of number is 0 or null, null is returned.

- Examples
`-- The value null is returned. select log2(null); -- The value null is returned. select log2(0); -- The value 3.0 is returned. select log2(8);`

## LOG10

- Syntax
`double log10(double <number>) double log10(decimal <number>)`

- Description
This function calculates the logarithm of number with the base number of 10. This function is an extension function of MaxCompute V2.0.

- Parameters
number: required. The value is of the DOUBLE or DECIMAL type.

- Return value
A value of the DOUBLE type is returned. The return value varies based on the following rules:
- If number is not of the DOUBLE or DECIMAL type, null is returned.
- If the value of number is 0 or null, null is returned.

- Examples
`-- The value null is returned. select log10(null); -- The value null is returned. select log10(0); -- The value 0.9030899869919435 is returned. select log10(8);`

## PI

- Syntax
`double pi()`

- Description
This function calculates the value of π. This function is an extension function of MaxCompute V2.0.

- Return value
A value of the DOUBLE type is returned.

- Examples
`-- The value 3.141592653589793 is returned. select pi();`

## RADIANS

- Syntax
`double radians(double <number>)`

- Description
This function converts a degree to a radian value. This function is an extension function of MaxCompute V2.0.

- Parameters
number: required. The value is of the DOUBLE type.

- Return value
A value of the DOUBLE type is returned. The return value varies based on the following rules:
- If number is not of the DOUBLE type, null is returned.
- If the value of number is null, null is returned.

- Examples
`-- The value 1.5707963267948966 is returned. select radians(90); -- The value 0.0 is returned. select radians(0); -- The value null is returned. select radians(null);`

## SIGN

- Syntax
`double sign(double <number>) double sign(decimal <number>)`

- Description
This function returns the sign of the input value. This function is an extension function of MaxCompute V2.0.

- Parameters
number: required. The value is of the DOUBLE or DECIMAL type.

- Return value
A value of the DOUBLE type is returned. The return value varies based on the following rules:
- If the value of number is a positive value, 1.0 is returned.
- If the value of number is a negative value, -1.0 is returned.
- If the value of number is 0, 0.0 is returned.
- If the value of number is null, null is returned.

- Examples
`-- The value -1.0 is returned. select sign(-2.5); -- The value 1.0 is returned. select sign(2.5); -- The value 0.0 is returned. select sign(0); -- The value null is returned. select sign(null);`

## SHIFTLEFT

- Syntax
`int shiftleft(tinyint|smallint|int <number1>, int <number2>) bigint shiftleft(bigint <number1>, int <number2>)`

- Description
This function shifts a value left by a specific number of places (<<). This function is an extension function of MaxCompute V2.0.

- Parameters
- number1: required. The value is an integer of the TINYINT, SMALLINT, INT, or BIGINT type.
- number2: required. The value is an integer of the INT type.

- Return value
A value of the INT or BIGINT type is returned. The return value varies based on the following rules:
- If number1 is not of the TINYINT, SMALLINT, INT, or BIGINT type, an error is returned.
- If number2 is not of the INT type, an error is returned.
- If the value of number1 or number2 is null, null is returned.

- Examples
`-- The value 4 is returned. The following statement shifts the binary value of 1 two places to the left (1<<2,0001 shifted to be 0100). select shiftleft(1,2); -- The value 32 is returned. The following statement shifts the binary value of 4 three places to the left (4<<3,0100 shifted to be 100000). select shiftleft(4,3); -- The value null is returned. select shiftleft(null,2);`

## SHIFTRIGHT

- Syntax
`int shiftright(tinyint|smallint|int <number1>, int <number2>) bigint shiftright(bigint <number1>, int <number2>)`

- Description
This function shifts a value right by a specific number of places (>>). This function is an extension function of MaxCompute V2.0.

- Parameters
- number1: required. The value is an integer of the TINYINT, SMALLINT, INT, or BIGINT type.
- number2: required. The value is an integer of the INT type.

- Return value
A value of the INT or BIGINT type is returned. The return value varies based on the following rules:
- If number1 is not of the TINYINT, SMALLINT, INT, or BIGINT type, an error is returned.
- If number2 is not of the INT type, an error is returned.
- If the value of number1 or number2 is null, null is returned.

- Examples
`-- The value 1 is returned. The following statement shifts the binary value of 4 two places to the right (4>>2,0100 shifted to be 0001). select shiftright(4,2); -- The value 4 is returned. The following statement shifts the binary value of 32 three places to the right (32>>3,100000 shifted to be 0100). select shiftright(32,3); -- The value null is returned. select shiftright(null,3);`

## SHIFTRIGHTUNSIGNED

- Syntax
`int shiftrightunsigned(tinyint|smallint|int <number1>, int <number2>) bigint shiftrightunsigned(bigint <number1>, int <number2>)`

- Description
This function shifts an unsigned value right by a specific number of places (>>>). This function is an extension function of MaxCompute V2.0.

- Parameters
- number1: required. The value is an integer of the TINYINT, SMALLINT, INT, or BIGINT type.
- number2: required. The value is an integer of the INT type.

- Return value
A value of the INT or BIGINT type is returned. The return value varies based on the following rules:
- If number1 is not of the TINYINT, SMALLINT, INT, or BIGINT type, an error is returned.
- If number2 is not of the INT type, an error is returned.
- If the value of number1 or number2 is null, null is returned.

- Examples
`-- The value 2 is returned. The following statement shifts the binary unsigned value of 8 two places to the right (8>>>2,1000 shifted to be 0010). select shiftrightunsigned(8,2); -- The value 1073741820 is returned. The following statement shifts the binary value of -14 two places to the right (-14>>>2, 11111111 11111111 11111111 11110010 shifted to be 00111111 11111111 11111111 11111100). select shiftrightunsigned(-14,2); -- The value null is returned. select shiftrightunsigned(-14,null);`

## UNHEX

- Syntax
`binary unhex(string <number>)`

- Description
This function converts a hexadecimal string to a string. This function is an extension function of MaxCompute V2.0.

- Parameters
number: required. The value is a hexadecimal string.

- Return value
A value of the BINARY type is returned. The return value varies based on the following rules:
- If the value of number is 0, an error is returned.
- If the value of number is null, null is returned.

- Examples
`-- The value abc is returned. select unhex('616263'); -- The value abc is returned. select unhex(616263); -- The value null is returned. select unhex(null);`

## WIDTH_BUCKET

- Syntax
`width_bucket(numeric <expr>, numeric <min_value>, numeric <max_value>, int <num_buckets>)`

- Description
This function specifies the number of buckets and the minimum and maximum values of the acceptable range for a bucket. It allows you to construct equi-width buckets, in which the bucket range is divided into intervals that have an identical size. It returns the ID of the bucket into which the value of a specific expression falls. This function supports the following data types: DECIMAL(precision,scale) in the MaxCompute V2.0 data type edition, BIGINT, INT, FLOAT, DOUBLE, and DECIMAL. For more information, see MaxCompute V2.0 data type edition. This function is an extension function of MaxCompute V2.0.

- Parameters
- expr: required. This parameter specifies the expression for which you want to identify the matching bucket ID.
- min_value: required. This parameter specifies the minimum value of the acceptable range for the bucket.
- max_value: required. This parameter specifies the maximum value of the acceptable range for the bucket. The value must be greater than min_value.
- num_buckets: required. This parameter specifies the number of buckets. The value must be greater than 0.

- Return value
A value of the BIGINT type is returned. The value ranges from 0 to num_buckets plus 1. The return value varies based on the following rules:
- If the value of expr is less than that of min_value, 0 is returned.
- If the value of expr is greater than that of max_value, the value of num_buckets plus 1 is returned.
- If the value of expr is null, null is returned. In other cases, the ID of the bucket into which the value
falls is returned. The bucket ID is calculated based on the following formula:
`Bucket ID = floor(num_buckets × (expr - min_value)/(max_value - min_value) + 1)`

. - If the value of min_value, max_value, or num_buckets is null, null is returned.

- Examples
- Example 1: The values of all input parameters are not null. Sample statement:

The following results are returned:`select key,value,width_bucket(value,100,500,5) as value_group from values (1,99), (2,100), (3,199), (4,200), (5,499), (6,500), (7,501), (8,NULL) as t(key,value);`

`+-------+--------+-------------+ | key | value | value_group | +-------+--------+-------------+ | 1 | 99 | 0 | | 2 | 100 | 1 | | 3 | 199 | 2 | | 4 | 200 | 2 | | 5 | 499 | 5 | | 6 | 500 | 6 | | 7 | 501 | 6 | | 8 | \N | \N | +-------+--------+-------------+`

- Example 2: The value of an input parameter is null. Sample statement:

The following results are returned:`select key,value,width_bucket(value,100,500,null) as value_group from values (1,99), (2,100), (3,199), (4,200), (5,499), (6,500), (7,501), (8,NULL) as t(key,value);`

`+------+-------+-------------+ | key | value | value_group | +------+-------+-------------+ | 1 | 99 | NULL | | 2 | 100 | NULL | | 3 | 199 | NULL | | 4 | 200 | NULL | | 5 | 499 | NULL | | 6 | 500 | NULL | | 7 | 501 | NULL | | 8 | NULL | NULL | +------+-------+-------------+`

- Example 1: The values of all input parameters are not null. Sample statement: