Bit String Functions and Operators

Updated on 2024-12-19 GMT+08:00

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Aside from the usual comparison operators, the following operators can be used. Bit string operands of &, |, and # must be of equal length. When bit shifting, the original length of the string is preserved by zero padding (if necessary).

||

Description: Connects bit strings.

For example:

    
       SELECT B'10001' || B'011' AS RESULT;
  result
----------
 10001011
(1 row)

&

Description: AND operation between bit strings

For example:

    
       SELECT B'10001' & B'01101' AS RESULT;
 result 
--------
 00001
(1 row)

|

Description: OR operation between bit strings

For example:

    
       SELECT B'10001' | B'01101' AS RESULT;
 result 
--------
 11101
(1 row)

#

Description: OR operation between bit strings if they are inconsistent. If the same positions in the two bit strings are both 1 or 0, the position returns 0.

For example:

    
       SELECT B'10001' # B'01101' AS RESULT;
 result 
--------
 11100
(1 row)

~

Description: NOT operation between bit strings

For example:

    
       SELECT ~B'10001'AS RESULT;
 result  
----------
 01110
(1 row)

<<

Description: binary left shift

For example:

     
        SELECT B'10001' << 3 AS RESULT;
 result  
----------
 01000
(1 row)

>>

Description: binary right shift

For example:

    
       SELECT B'10001' >> 2 AS RESULT;
 result  
----------
 00100
(1 row)

The following SQL-standard functions work on bit strings as well as character strings: length, bit_length, octet_length, position, substring, and overlay.

The following functions work on bit strings as well as binary strings: get_bit and set_bit. When working with a bit string, these functions number the first (leftmost) bit of the string as bit 0.

Integers and bits can be mutually converted. For example:

    
     
       
       SELECT 44::bit(10) AS RESULT;
   result
------------
 0000101100
(1 row)

SELECT 44::bit(3) AS RESULT;
 result 
--------
 100
(1 row)

SELECT cast(-44 as bit(12)) AS RESULT;
    result    
--------------
 111111010100
(1 row)

SELECT '1110'::bit(4)::integer AS RESULT;
 result 
--------
     14
(1 row)

      

    
   