ClickHouse/docs/en/functions/comparison_functions.md
2018-03-26 17:00:55 +03:00

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# Comparison functions
Comparison functions always return 0 or 1 (Uint8).
The following types can be compared:
- numbers
- strings and fixed strings
- dates
- dates with times
within each group, but not between different groups.
For example, you can't compare a date with a string. You have to use a function to convert the string to a date, or vice versa.
Strings are compared by bytes. A shorter string is smaller than all strings that start with it and that contain at least one more character.
Note: Up until version 1.1.54134, signed and unsigned numbers were compared the same way as in C++. In other words, you could get an incorrect result in cases like SELECT 9223372036854775807 > -1. This behavior changed in version 1.1.54134 and is now mathematically correct.
## equals, a = b and a == b operator
## notEquals, a ! operator= b and a `<>` b
## less, `< operator`
## greater, `> operator`
## lessOrEquals, `<= operator`
## greaterOrEquals, `>= operator`