explain et index

gistfile1.txt

//Affiche les index positionnés sur ma table
SHOW INDEX FROM MA_TABLE 

SELECT
      *
   FROM
      tblA,
      tblB,
      tblC
   WHERE
          tblA.col1 = tblB.col1
      AND tblA.col2 = tblC.col1;
   
And EXPLAIN for the query:
   +-------+------+---------------+------+---------+------+------+-------------+
   | table | type | possible_keys | key  | key_len | ref  | rows | Extra       |
   +-------+------+---------------+------+---------+------+------+-------------+
   | tblA  | ALL  | NULL          | NULL |    NULL | NULL | 1000 |             |
   | tblB  | ALL  | NULL          | NULL |    NULL | NULL | 1000 | Using where |
   | tblC  | ALL  | NULL          | NULL |    NULL | NULL | 1000 | Using where |
   +-------+------+---------------+------+---------+------+------+-------------+

see http://hackmysql.com/case4