Comments - storage/retrieval of ASCII(32)
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It is because char(n) columns strip trailing spaces when selected. So chr(32), a single space, gets interpreted as the empty string. See here:
https://mariadb.com/kb/en/char/
" Trailing spaces are removed when CHAR values are retrieved"
You can set the SQL_MODE to include PAD_CHAR_TO_FULL_LENGTH to disable this behaviour and be able to select the chr(32):
MariaDB> set sql_mode = concat(@@sql_mode, ',PAD_CHAR_TO_FULL_LENGTH'); MariaDB> create table t5 (a char(1)); MariaDB> insert into t5 values ('a'), (' '); MariaDB> select a, length(a), ascii(a) from t5; +------+-----------+----------+ | a | length(a) | ascii(a) | +------+-----------+----------+ | a | 1 | 97 | | | 1 | 32 | +------+-----------+----------+You can also use VARCHAR(1) as a type instead of char(1), it doesn't strip trailing spaces and thus does not require setting the SQL_MODE.