hi guys, i want to know function base-index

[james zhang]

hi:
I have a table, like
CREATE TABLE test (
id INT,
name CHAR(30),
status INT
);

INDEX ON name.

but I use this query,
SELECT * FROM test WHERE char_length(name) > 5;

explain this query is right use where, but I remember mysql not support function base-index, why explain query is right use where?