MySQL Tutorial/Encryption Compression Functions/UNCOMPRESS
UNCOMPRESS(string_to_uncompress) uncompresses a string compressed by the COMPRESS() function.
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mysql> mysql> SELECT UNCOMPRESS(COMPRESS("any string")); +------------------------------------+ | UNCOMPRESS(COMPRESS("any string")) | +------------------------------------+ | any string | +------------------------------------+ 1 row in set (0.00 sec) mysql> mysql> SELECT UNCOMPRESS("any string"); +--------------------------+ | UNCOMPRESS("any string") | +--------------------------+ | NULL | +--------------------------+ 1 row in set, 1 warning (0.00 sec) mysql></source>