CREATE OR REPLACE TABLE t1 (

  c1 varchar(10),

  KEY(c1)

) CHARACTER SET latin1;

INSERT INTO t1 VALUES ('a');

INSERT INTO t1 VALUES ('b');

INSERT INTO t1 VALUES ('c');

INSERT INTO t1 VALUES ('d');

INSERT INTO t1 VALUES ('e');

INSERT INTO t1 VALUES ('f');

INSERT INTO t1 VALUES ('g');

INSERT INTO t1 VALUES ('h');

INSERT INTO t1 VALUES ('i');

INSERT INTO t1 VALUES ('j');

SET note_verbosity=all;

EXPLAIN SELECT * FROM t1 WHERE c1=10;

SHOW WARNINGS;

+-------+------+-------------------------------------------------------------------------------------------------+

| Level | Code | Message                                                                                         |

+-------+------+-------------------------------------------------------------------------------------------------+

| Note  | 1105 | Cannot use key `c1` part[0] for lookup: `test`.`t1`.`c1` of type `varchar` = "10" of type `int` |

+-------+------+-------------------------------------------------------------------------------------------------+

EXPLAIN SELECT * FROM t1 WHERE c1<10;

EXPLAIN SELECT * FROM t1 WHERE c1 BETWEEN 10 AND 11;

EXPLAIN SELECT * FROM t1 WHERE c1 IN (_latin1'a' COLLATE latin1_german2_ci,'b');