ClickHouse/docs/en/functions/comparison_functions.md

# 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`