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# Comparison functions {#comparison-functions}
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Comparison functions always return 0 or 1 (Uint8).
The following types can be compared:
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- numbers
- strings and fixed strings
- dates
- dates with times
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within each group, but not between different groups.
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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.
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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.
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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.
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## equals, a = b and a == b operator {#function-equals}
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## notEquals, a ! operator= b and a `<>` b {#function-notequals}
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## less, `< operator` {#function-less}
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## greater, `> operator` {#function-greater}
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## lessOrEquals, `<= operator` {#function-lessorequals}
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## greaterOrEquals, `>= operator` {#function-greaterorequals}
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[Original article ](https://clickhouse.tech/docs/en/query_language/functions/comparison_functions/ ) <!--hide-->