Bit String Types

Compared with the original MogDB, Dolphin modifies the bit string types as follows:

The data of the bit type is of variable length up to the maximum length n. Longer strings will be rejected. The data of the bit varying type is of variable length up to the maximum length n. Longer strings will be rejected.
If one explicitly casts a bit-string value to bit(n), it will be truncated or zero-padded on the left to be exactly n bits, without raising an error.

--Create a table.
MogDB=# CREATE TABLE bit_type_t1 
(
    BT_COL1 INTEGER,
    BT_COL2 BIT(3),
    BT_COL3 BIT VARYING(5)
) ;

--Data is converted if it exceeds the length of this data type.
MogDB=# INSERT INTO bit_type_t1 VALUES(2, B'1000'::bit(3), B'101');

--View data.
MogDB=# SELECT * FROM bit_type_t1;
 bt_col1 | bt_col2 | bt_col3 
---------+---------+---------
       2 | 100     | 101
(2 rows)

--If the length of a character string is insufficient, the character string is converted to bit(n) and zeros are padded on the left.
MogDB=# SELECT B'10'::bit(4);
  bit   
--------
 000010
(1 row)

--Delete a table.
MogDB=# DROP TABLE bit_type_t1;