Hologres:Data types

CREATE TABLE test_data_type (
  tswtz_column TIMESTAMP WITH TIME ZONE,
  date_column date,
  decimal_column decimal(38, 10),
  char_column char(20),
  varchar_volumn varchar(225)
);

INSERT INTO test_data_type
VALUES ('2004-10-19 08:08:08', '2004-10-19', 123.456, 'abcd', 'a');

SELECT * FROM test_data_type;
      tswtz_column      | date_column | decimal_column |     char_column      | varchar_volumn 
------------------------+-------------+----------------+----------------------+----------------
 2004-10-19 08:08:08+08 | 2004-10-19  | 123.4560000000 | abcd                 | a
(1 row)

// The BIT and VARBIT data types.

CREATE TABLE test (a BIT(3), b BIT VARYING(5));
INSERT INTO test VALUES (B'101', B'00');
INSERT INTO test VALUES (B'10', B'101');

ERROR:  bit string length 2 does not match type bit(3)

INSERT INTO test VALUES (B'10'::bit(3), B'101');
SELECT * FROM test;

  a  |  b
-----+-----
 101 | 00
 100 | 101

//BYTEA

SET bytea_output = 'escape';

SELECT 'abc \153\154\155 \052\251\124'::bytea;
     bytea
----------------
 abc klm *\251T
 
RESET bytea_output;  -- 'hex' by default

SELECT 'abc \153\154\155 \052\251\124'::bytea;
          bytea
--------------------------
 \x616263206b6c6d202aa954
(1 row)

• int4[]
• int8[]
• float4[]
• float8[]
• boolean[]
• text[]

• Declare an array.

  CREATE TABLE array_example(
  int4_array int4[],
  int8_array int8[],
  float4_array float4[],
  float8_array float8[],
  boolean_array boolean[],
  text_array text[]);

• Add an element to an array.
  • Use the ARRAY keyword.

    INSERT INTO array_example(
    int4_array,
    int8_array,
    float4_array,
    float8_array,
    boolean_array,
    text_array)
    VALUES (ARRAY[1, 2, 3, 4],
    ARRAY[1, 2, 3, 4],
    ARRAY[1.0, 2.0],
    ARRAY[1.0, 2.0, 3.0],
    ARRAY[true, true, false],
    ARRAY['foo1', 'foo2', 'foo3']);

  • Use the {} expression.

    INSERT INTO array_example(
    int4_array,
    int8_array,
    float4_array,
    float8_array,
    boolean_array,
    text_array)
    VALUES ('{1, 2, 3, 4}',
    '{1, 2, 3, 4}',
    '{1.0, 2.0}',
    '{1.0, 2.0, 3.0}',
    '{true, true, false}',
    '{"foo1", "foo2", "foo3"}');

• Query an array.
  • Query an element in an array.

    SELECT int4_array[3] FROM array_example;

  • Query multiple elements in an array.

    SELECT int4_array[1:2] FROM array_example;