PostgreSQL 9.2.9 Documentation | ||||
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This section describes functions and operators for examining
and manipulating bit strings, that is values of the types
`bit` and `bit varying`.
Aside from the usual comparison operators, the operators shown in
Table
9-10 can be used. Bit string operands of `&`, `|`, and `#` must be of equal length. When bit shifting, the
original length of the string is preserved, as shown in the
examples.

Table 9-10. Bit String Operators

Operator | Description | Example | Result |
---|---|---|---|

|| |
concatenation | B'10001' || B'011' |
10001011 |

& |
bitwise AND | B'10001' & B'01101' |
00001 |

| |
bitwise OR | B'10001' | B'01101' |
11101 |

# |
bitwise XOR | B'10001' # B'01101' |
11100 |

~ |
bitwise NOT | ~ B'10001' |
01110 |

<< |
bitwise shift left | B'10001' << 3 |
01000 |

>> |
bitwise shift right | B'10001' >> 2 |
00100 |

The following SQL-standard
functions work on bit strings as well as character strings:
` length`,

`bit_length`

`octet_length`

`position`

`substring`

`overlay`

The following functions work on bit strings as well as binary
strings: ` get_bit`,

`set_bit`

In addition, it is possible to cast integral values to and
from type `bit`. Some examples:

44::bit(10)000010110044::bit(3)100cast(-44 as bit(12))111111010100'1110'::bit(4)::integer14

Note that casting to just "bit"
means casting to `bit(1)`, and so will
deliver only the least significant bit of the integer.

Note:Prior to PostgreSQL 8.0, casting an integer tobit(n)would copy the leftmostnbits of the integer, whereas now it copies the rightmostnbits. Also, casting an integer to a bit string width wider than the integer itself will sign-extend on the left.