This topic describes the comparison functions that are supported by PolarDB-X.

The following table describes the comparison functions that are supported by PolarDB-X.

Function Description
COALESCE() Returns the first non-NULL expression.
GREATEST() Returns the largest value in a list.
IN() Tests whether a specified value or field is included in a list.
ISNULL() Tests whether an expression is NULL.
LEAST() Returns the smallest value in a list.
STRCMP() Compares the s1 string and the s2 string based on ASCII values. If the ASCII values of the strings are the same, the value 0 is returned. If the ASCII value of the s1 string is larger than that of the s2 string, the value 1 is returned. If the ASCII value of the s1 string is smaller than that of the s2 string, the value -1 is returned.