PostgreSQL 7.4 Documentation | ||||
---|---|---|---|---|

Prev | Fast Backward | Fast Forward | Next |

**Table of Contents**- 9.1. Logical Operators
- 9.2. Comparison Operators
- 9.3. Mathematical Functions and Operators
- 9.4. String Functions and Operators
- 9.5. Binary String Functions and Operators
- 9.6. Pattern Matching
- 9.6.1.
`LIKE`

- 9.6.2.
`SIMILAR TO`

and SQL99 Regular Expressions - 9.6.3. POSIX Regular Expressions

- 9.6.1.
- 9.7. Data Type Formatting Functions
- 9.8. Date/Time Functions and Operators
- 9.8.1.
`EXTRACT`

,`date_part`

- 9.8.2.
`date_trunc`

- 9.8.3.
`AT TIME ZONE` - 9.8.4. Current Date/Time

- 9.8.1.
- 9.9. Geometric Functions and Operators
- 9.10. Network Address Type Functions
- 9.11. Sequence-Manipulation Functions
- 9.12. Conditional Expressions
- 9.13. Miscellaneous Functions
- 9.14. Array Functions and Operators
- 9.15. Aggregate Functions
- 9.16. Subquery Expressions
- 9.17. Row and Array Comparisons
- 9.17.1.
`IN` - 9.17.2.
`NOT IN` - 9.17.3.
`ANY`/`SOME`(array) - 9.17.4.
`ALL`(array) - 9.17.5. Row-wise Comparison

- 9.17.1.

PostgreSQL provides a large number of
functions and operators for the built-in data types. Users can also
define their own functions and operators, as described in
Part V. The
psql commands `\df` and
`\do` can be used to show the list of all actually
available functions and operators, respectively.

If you are concerned about portability then take note that most of the functions and operators described in this chapter, with the exception of the most trivial arithmetic and comparison operators and some explicitly marked functions, are not specified by the SQL standard. Some of the extended functionality is present in other SQL database management systems, and in many cases this functionality is compatible and consistent between the various implementations.

The usual logical operators are available:

AND |

OR |

NOT |

a | b | a AND b | a OR b |
---|---|---|---|

TRUE | TRUE | TRUE | TRUE |

TRUE | FALSE | FALSE | TRUE |

TRUE | NULL | NULL | TRUE |

FALSE | FALSE | FALSE | FALSE |

FALSE | NULL | FALSE | NULL |

NULL | NULL | NULL | NULL |

The operators `AND` and `OR` are
commutative, that is, you can switch the left and right operand
without affecting the result. But see Section 4.2.11 for more information about the
order of evaluation of subexpressions.