MySQL in a Nutshell, 2nd Edition

Name

COMPRESS()

Synopsis

COMPRESS(string)

This function returns a given string after compressing it. It requires MySQL to have been compiled with a compression library (e.g., zlib). If it wasn’t, a NULL value will be returned. This statement is available as of version 4.1 of MySQL. Here is an example:

UPDATE students_records
SET personal_essay =
(SELECT COMPRESS(essay)
 FROM student_applications
 WHERE applicant_id = '7382') AS derived1
WHERE student_id = '433302000';

If you want to store a value that was compressed with this function, it’s best to store it in a BLOB column, since the results are binary. Use UNCOMPRESS() to uncompress a string that was compressed with this function.