How do I optimize a full table query without an index?

dct121127

How to optimize a full table query without an index?

fanfan1980

Build indexes or paste SQL statements

四不像君

Set the field a bit thinner, use like 'aa%' when querying the character format, don't use substring

jccg1124

Last time, where did I say that the effect of like '% a%' is better than that of 'a%'?