Backslashes in data

Backslashes multiply weirdly:



SELECT 'a\b' RLIKE 'a\b';

returns 1, as does...



SELECT 'a\\b' RLIKE 'a\\\\b';

because in a pair of backslashes, the second is not escaped by the first, so to compare two literals you double each backslash in the RLIKE argument. But if you are querying a table for such a string from the MySQL client, this doubling happens twice--once in the client, and once in the database--so to find a column value matching 'a\\b', you need to write...



SELECT desc FROM xxx WHERE desc RLIKE 'aa\\\\\\\\bb';

That's eight backslashes to match two!