Functions

1. Aggregate functions

2. Mathematical functions

TSQL supports the mathematical functions listed in the following table and the trigonometric functions listed in the next section. The following data types are supported for the input values for most of the mathematical functions and all of the trigonometric functions:

• INT
• BIGINT
• FLOAT
• DOUBLE
• SMALLINT

Examples

The math_func_demo table is used in the following examples of mathematical function. The math_func_demo table contains the following data.

select * from math_func_demo;
+---------------+-----------------------+
|    integer    |         float         |
+---------------+-----------------------+
| 2010          | 17.4                  |
| -2002         | -1.2                  |
| 2001          | 1.2                   |
| 6005          | 1.2                   |
+---------------+-----------------------+

• ABS(x)

SELECT ABS(`integer`) FROM math_func_demo;
+------------+
|   EXPR$0   |
+------------+
| 2010       |
| 2002       |
| 2001       |
| 6005       |
+------------+
4 rows selected (0.357 seconds)

• CEIL(x)

SELECT CEIL(`float`) FROM math_func_demo;
+------------+
|   EXPR$0   |
+------------+
| 18.0       |
| -1.0       |
| 2.0        |
| 2.0        |
+------------+
4 rows selected (0.647 seconds)

• FLOOR(x)

SELECT FLOOR(`float`) FROM math_func_demo;
+------------+
|   EXPR$0   |
+------------+
| 17.0       |
| -2.0       |
| 1.0        |
| 1.0        |
+------------+
4 rows selected (0.11 seconds)

• ROUND(x) and ROUND(x, y):The ROUND(x) and Round (x, y) function examples return the nearest integer and an approximate number that is rounded to four decimal places, respectively.

SELECT ROUND(`float`) FROM math_func_demo;
+------------+
|   EXPR$0   |
+------------+
| 3.0        |
| -1.0       |
| 1.0        |
| 1.0        |
+------------+
4 rows selected (0.061 seconds)
SELECT ROUND(`float`, 4) FROM math_func_demo;
+------------+
|   EXPR$0   |
+------------+
| 3.1416     |
| -1.2       |
| 1.2        |
| 1.2        |
+------------+
4 rows selected (0.059 seconds)

• LOG(x, y), LOG10(x), and LOG(x)The LOG(x, y), LOG10(x), and LOG(x) function examples return the base 2 logarithm of 64, the base 10 logarithm of 100, and the base e logarithm of 7.5, respectively.

SELECT LOG(2, 64) FROM (VALUES(1));
+------------+
|   EXPR$0   |
+------------+
| 6.0        |
+------------+
1 row selected (0.069 seconds)
SELECT LOG10(100) FROM (VALUES(1));
+------------+
|   EXPR$0   |
+------------+
| 2.0        |
+------------+
1 row selected (0.203 seconds)
SELECT LOG(7.5) FROM (VALUES(1));
+---------------------+
|       EXPR$0        |
+---------------------+
| 2.0149030205422647  |
+---------------------+
1 row selected (0.139 seconds)

3. Trigonometric functions

TSQL supports the following trigonometric functions. These functions return values of the FLOAT8 data type.

• SIN(x)
  Returns the sine of x.
• COS(x)
  Returns the cosine of x.
  
• TAN(x)
  Returns the tangent of x.
  
• ASIN(x)
  Returns the arcsine of x.
  
• ACOS(x)
  Returns the arccosine of x.
  
• ATAN(x)
  Returns the arctangent of x.
  
• SINH(x)
  Returns the hyperbolic sine of x.
  
• COSH(x)
  Returns the hyperbolic cosine of x.
  
• TANH(x)
  Returns the hyperbolic tangent of x.

Examples

SELECT RADIANS(30) AS Degrees FROM (VALUES(1));
+------------+
|  Degrees   |
+------------+
| 0.7853981633974483 |
+------------+
1 row selected (0.045 seconds)
SELECT SIN(0.7853981633974483) AS `Sine of 30 degrees` FROM (VALUES(1));
+-----------------------+
|  Sine of 45 degrees   |
+-----------------------+
|  0.7071067811865475   |
+-----------------------+
1 row selected (0.059 seconds)
SELECT TAN(0.7853981633974483) AS `Tangent of 30 degrees` from (VALUES(1));
+-----------------------+
| Tangent of 45 degrees |
+-----------------------+
| 0.9999999999999999    |
+-----------------------+

4. String functions

The following table lists the string functions that are supported by TSQL.

Examples

• CONCAT

Syntax: CONCAT(string [,string [, ...]])
The CONCAT function connects strings.

SELECT CONCAT('Drill', ' ', 1.0, ' ', 'release') FROM (VALUES(1));
+--------------------+
|       EXPR$0       |
+--------------------+
| Drill 1.0 release  |
+--------------------+
1 row selected (0.134 seconds)

• INITCAP

Syntax: INITCAP(string)
The INITCAP function returns a string where the first character is capitalized.

SELECT INITCAP('china beijing') FROM (VALUES(1));
+---------------------------+
|          EXPR$0           |
+---------------------------+
| China Beijing             |
+---------------------------+
1 row selected (0.106 seconds)

• LENGTH

Syntax: LENGTH(string [, encoding])
The LENGTH function returns the number of characters in a string.

SELECT LENGTH('Hangzhou') FROM (VALUES(1));
+------------+
|   EXPR$0   |
+------------+
| 8          |
+------------+
1 row selected (0.127 seconds)

• LOWER

Syntax: LOWER(string)
The LOWER function converts uppercase characters in a string to lowercase characters.

SELECT LOWER('China Beijing') FROM (VALUES(1));
+---------------+
|    EXPR$0     |
+---------------+
| china beijing  |
+---------------+
1 row selected (0.103 seconds)

• LPAD

Syntax: LPAD(string,length [, fill text])
The LPAD function left-pads a string to a specified length with the fill text. If the fill text fails to pad the string to the specified length, spaces are added to pad the string to the specified length. If the string length exceeds the specified length, the string is truncated to the specified length.

SELECT LPAD('hi', 5, 'xy') FROM (VALUES(1));
+------------------------------+
|            EXPR$0            |
+------------------------------+
| xyxhi                        |
+------------------------------+
1 row selected (0.132 seconds)

• LTRIM

Syntax: LTRIM(string1, string2)
The LTRIM function removes all the characters that are contained in the specified set (string2) from the left side of the input string (string1).

SELECT LTRIM('zzzytest', 'xyz') FROM (VALUES(1));
+------------+
|   EXPR$0   |
+------------+
| test       |
+------------+
1 row selected (0.131 seconds)

• REGEXP_REPLACE

Syntax: REGEXP_REPLACE(source_char, pattern, replacement)
The REGEXP_REPLACE function replaces the substrings that match the Java regular expression pattern in the string with the specified characters.

SELECT REGEXP_REPLACE('abc, acd, ade, aef', 'a', 'b') FROM (VALUES(1));
+---------------------+
|       EXPR$0        |
+---------------------+
| bbc, bcd, bde, bef  |
+---------------------+
1 row selected (0.105 seconds)
SELECT REGEXP_REPLACE('abc, acd, ade, aef', 'a.','b') FROM (VALUES(1));
+-----------------+
|     EXPR$0      |
+-----------------+
| bc, bd, be, bf  |
+-----------------+
1 row selected (0.113 seconds)

• RPADSyntax: RPAD (string, length [, fill text])
  The RPAD function right-pads a string to the specified length. If you do not specify the fill text or the fill text fails to pad the string to the specified length, spaces are added to the end of the specified characters. The specified characters follow a specific keyword. If the string length exceeds the specified length, the string is truncated to the specified length.

SELECT RPAD('hi', 5, 'xy') FROM (VALUES(1));
+-------------------------+
|         EXPR$0          |
+-------------------------+
| hixyx                   |
+-------------------------+
1 row selected (0.107 seconds)

• RTRIM

Syntax: RTRIM(string1, string2)
The RTRIM function removes all the characters that are contained in the specified set (string2) from the right side of the input string (string1).

SELECT RTRIM('testxxzx', 'xyz') from (VALUES(1));
+--------------------+
|       EXPR$0       |
+--------------------+
| tes                |
+--------------------+
1 row selected (0.102 seconds)

• STRPOS

Syntax: STRPOS(string, substring)
The STRPOS function returns the position of a substring in a string.

SELECT STRPOS('high', 'ig') FROM (VALUES(1));
+------------+
|   EXPR$0   |
+------------+
| 2          |
+------------+
1 row selected (0.22 seconds)

• SUBSTR

Syntax: SUBSTR(string, x, y)
The SUBSTR function returns the substring from the x to x+y position in a string. The y argument is optional.

SELECT SUBSTR('China Beijing', 7) FROM (VALUES(1));
+------------+
|   EXPR$0   |
+------------+
| Beijing    |
+------------+
1 row selected (0.134 seconds)
SELECT SUBSTR('China Beijing', 3, 2) FROM (VALUES(1));
+------------+
|   EXPR$0   |
+------------+
| in         |
+------------+
1 row selected (0.129 seconds)

• TRIM

Syntax: TRIM ([leading | trailing | both] [string1] from string2)
The TRIM function removes all the characters that are contained in the specified set (string1) from the left side or the right side of a string (string2).

SELECT TRIM(trailing 'A' from 'AABBAA') FROM (VALUES(1));
+------------+
|   EXPR$0   |
+------------+
| AABB       |
+------------+
1 row selected (0.172 seconds)
SELECT TRIM(both 'A' from 'AABBAA') FROM (VALUES(1));
+---------------+
|    EXPR$0     |
+---------------+
| BB            |
+---------------+
1 row selected (0.104 seconds)
SELECT TRIM(leading 'A' from 'AABBAA') FROM (VALUES(1));
+-----------------+
|     EXPR$0      |
+-----------------+
| BBAA            |
+-----------------+
1 row selected (0.101 seconds)

• UPPER

Syntax: UPPER(string)
The UPPER function converts lowercase characters in a string to uppercase characters.

SELECT UPPER('china beijing') FROM (VALUES(1));
+---------------+
|    EXPR$0     |
+---------------+
| CHINA BEIJING |
+---------------+
1 row selected (0.081 seconds)

5. Timestamp functions

The following table lists the timestamp functions that are supported by TSQL.

The following examples are used to describe how to use the timestamp functions.

SELECT CURRENT_DATE FROM (VALUES(1));
+---------------+
| CURRENT_DATE  |
+---------------+
| 2019-11-27    |
+---------------+

SELECT EXTRACT(hour FROM TIME '17:12:28.5') FROM (VALUES(1));
+---------+
| EXPR$0  |
+---------+
| 17      |
+---------+

SELECT EXTRACT(SECOND FROM TIMESTAMP '2001-02-16 20:38:40') FROM (VALUES(1));
+---------+
| EXPR$0  |
+---------+
| 40.0    |
+---------+

SELECT DATE_DIFF(TIMESTAMP '2001-02-16 20:38:40', interval '5' minute) FROM (VALUES(1));
+------------------------+
|         EXPR$0         |
+------------------------+
| 2001-02-16 20:33:40.0 |
+------------------------+

SELECT DATE_ADD(TIMESTAMP '2001-02-16 20:38:40', interval '5' minute) FROM (VALUES(1));
+------------------------+
|         EXPR$0         |
+------------------------+
| 2001-02-16 20:43:40.0 |
+------------------------+

SELECT tumble(TIMESTAMP '2001-02-16 20:38:40', interval '5' minute) FROM (VALUES(1));
+------------------------+
|         EXPR$0         |
+------------------------+
| 2001-02-16 20:35:00.0  |
+------------------------+

6. Data type conversion functions

6.1 CAST

The CAST function converts the value of a specified expression from one data type to another data type. A single value can be obtained based on the specified expression.

• Syntax

`

CAST (<expression> AS <data type>)

• Syntax element: expression

The expression element specifies one or more values whose data types are to be converted. The specified expression consists of operators and SQL functions.

• Syntax element: data type

The data type element specifies the target data type, such as INT or DATE.

This topic provides the following examples. In these examples, a string is converted to a number, a number is converted to a string, and a number is converted from one data type to another data type, respectively.

SELECT CAST(456 as VARCHAR(3)) FROM (VALUES(1));
+------------+
|   EXPR$0   |
+------------+
| 456        |
+------------+
1 row selected (0.08 seconds)
SELECT CAST(456 as CHAR(3)) FROM (VALUES(1));
+------------+
|   EXPR$0   |
+------------+
| 456        |
+------------+
1 row selected (0.093 seconds)

6.2 Convert timestamp, date, and time data types

TSQL supports the following date and time formats:

• 2008-12-15
  
• 22:55:55.123…
  

If the date and time use other formats, use data type conversion functions to perform the following operations:

• Convert values of the TIMESTAMP, DATE, TIME, INT, FLOAT, or DOUBLE data type to strings of the VARCHAR data type.
• Convert strings to values of the DATE data type.
• Convert strings to values of the NUMBER data type.

The following table lists the data type conversion functions that you can use in TSQL queries.

Format symbols for date and time conversion

The following table lists the Joda-Time formatting symbols that are used for date and time conversion.

• TO_CHAR example:

The TO_CHAR function converts a number, date, time, or timestamp expression to a string.

SELECT TO_CHAR(1256.789383, '#,###.###') FROM (VALUES(1));
+------------+
|   EXPR$0   |
+------------+
| 1,256.789  |
+------------+
1 row selected (1.767 seconds)
SELECT TO_CHAR(125677.4567, '#,###.###') FROM (VALUES(1));
+--------------+
|    EXPR$0    |
+--------------+
| 125,677.457  |
+--------------+
1 row selected (0.083 seconds)
SELECT TO_CHAR((CAST('2008-2-23' AS DATE)), 'yyyy-MMM-dd') FROM (VALUES(1));
+--------------+
|    EXPR$0    |
+--------------+
| 2008-Feb-23  |
+--------------+
1 row selected (0.166 seconds)
SELECT TO_CHAR(CAST('12:20:30' AS TIME), 'HH mm ss') FROM (VALUES(1));
+------------+
|   EXPR$0   |
+------------+
| 12 20 30   |
+------------+
1 row selected (0.07 seconds)
SELECT TO_CHAR(CAST('2015-2-23 12:00:00' AS TIMESTAMP), 'yyyy MMM dd HH:mm:ss') FROM (VALUES(1));
+-----------------------+
|        EXPR$0         |
+-----------------------+
| 2015 Feb 23 12:00:00  |
+-----------------------+
1 row selected (0.142 seconds)

• TO_DATE examples:The first example converts a string to a date. The second example extracts the year component from a date to verify that TSQL recognizes the date as a value of the DATE type.

SELECT TO_DATE('2015-FEB-23', 'yyyy-MMM-dd') FROM (VALUES(1));
+------------+
|   EXPR$0   |
+------------+
| 2015-02-23 |
+------------+
1 row selected (0.077 seconds)
SELECT EXTRACT(year from mydate) `extracted year` FROM (SELECT TO_DATE('2015-FEB-23', 'yyyy-MMM-dd') AS mydate FROM (VALUES(1)));
+------------+
|   myyear   |
+------------+
| 2015       |
+------------+
1 row selected (0.128 seconds)

The following example converts a Unix timestamp to a date.

SELECT TO_DATE(1427849046000) FROM (VALUES(1));
+------------+
|   EXPR$0   |
+------------+
| 2015-04-01 |
+------------+
1 row selected (0.082 seconds)

• TO_TIME example:The TO_TIME function converts a string to a time value.

SELECT TO_TIME('12:20:30', 'HH:mm:ss') FROM (VALUES(1));
+------------+
|   EXPR$0   |
+------------+
| 12:20:30   |
+------------+
1 row selected (0.067 seconds)
SELECT to_time(82855000) FROM (VALUES(1));
+------------+
|   EXPR$0   |
+------------+
| 23:00:55   |
+------------+
1 row selected (0.086 seconds)

• TO_TIMESTAMP example:

The TO_TIMESTAMP function converts a date to a timestamp.

SELECT TO_TIMESTAMP('2008-2-23 12:00:00', 'yyyy-MM-dd HH:mm:ss') FROM (VALUES(1));
+------------------------+
|         EXPR$0         |
+------------------------+
| 2008-02-23 12:00:00.0  |
+------------------------+
1 row selected (0.126 seconds)

The following example converts the Unix time to a timestamp.

SELECT TO_TIMESTAMP(1427936330) FROM (VALUES(1));
+------------------------+
|         EXPR$0         |
+------------------------+
| 2015-04-01 17:58:50.0  |
+------------------------+
1 row selected (0.114 seconds)

The following example converts a Coordinated Universal Time (UTC) date to a timestamp that includes a time zone offset in its value.

SELECT TO_TIMESTAMP('2015-03-30 20:49:59.0 UTC', 'YYYY-MM-dd HH:mm:ss.s z') AS Original, 
       TO_CHAR(TO_TIMESTAMP('2015-03-30 20:49:59.0 UTC', 'YYYY-MM-dd HH:mm:ss.s z'), 'z') AS New_TZ 
FROM (VALUES(1));
+------------------------+---------+
|        Original        | New_TZ  |
+------------------------+---------+
| 2015-03-30 20:49:00.0  | UTC     |
+------------------------+---------+
1 row selected (0.148 seconds)