User-defined collation sequences

By default, when QDB compares two text values, the result of the comparison is determined using memcmp(), regardless of the text encoding. QDB lets you supply arbitrary comparison functions, known as user-defined collation sequences, to use instead of memcmp(). See Writing User-Defined Functions for more information.

QDB features three built-in collation sequences:

BINARY

Compare string data using memcmp(), regardless of text encoding. This is the default comparison method.

NOCASE

The same as BINARY, except that the 26 uppercase characters used by the English language are converted to their lowercase equivalents before the comparison is performed.

RTRIM

The same as BINARY, except that trailing spaces are ignored.

The last two sequences are intended for testing purposes.