Question

There is a table with the following stucture:

Here are the data in this table:

Ok, let’s try the following:

SELECT
LOWER(md5_upper_bin), 
LOWER(md5_upper_ge_ci), 
UPPER(md5_lower_bin),
UPPER(md5_lower_ge_ci) 
FROM qwew

The result is:

The question: why the postfix _bin have been ignored? According to MySQL manual, we can say that _bin affects to such functions like LOWER and UPPER too (and make them not working because binary-type collaction is used in these fields). But we’ve got another results in practice. Why?

Answer 1

CHAR and VARCHAR store nonbinary strings, not binary strings. You have to change the actual column type to BINARY or VARBINARY for the _bin collation to affect UPPER and LOWER functions applied to data within them.