mysl mysam table, temporary table and index

Question

Would it be faster to add index for "t.name"? Does the index for "t.name" is preserved when the temporary table "x" is created?

SELECT x.id 
FROM 
    (SELECT t.name FROM t WHERE id_group=1 LIMIT 2000) AS x
WHERE x.name LIKE 'a%' LIMIT 0,12

Answer 1

in general when you do simple like on query statement on some column, this column should be an index, except some other cases

in this case i presume x.name is ordinary varchar 255 so you definately should do it