608
608
SELECT DISTINCT a,a FROM t1 WHERE b < 12 ORDER BY a;
611
CREATE TABLE t1 (a CHAR(1));
612
INSERT INTO t1 VALUES('A'), (0);
613
SELECT a FROM t1 WHERE a=0;
617
SELECT DISTINCT a FROM t1 WHERE a=0;
622
CREATE TABLE t1 (a DATE);
623
INSERT INTO t1 VALUES ('1972-07-29'), ('1972-02-06');
624
EXPLAIN SELECT (SELECT DISTINCT a FROM t1 WHERE a = '2002-08-03');
625
id select_type table type possible_keys key key_len ref rows Extra
626
1 PRIMARY NULL NULL NULL NULL NULL NULL NULL No tables used
627
2 SUBQUERY t1 ALL NULL NULL NULL NULL 2 Using where
628
EXPLAIN SELECT (SELECT DISTINCT ADDDATE(a,1) FROM t1
629
WHERE ADDDATE(a,1) = '2002-08-03');
630
id select_type table type possible_keys key key_len ref rows Extra
631
1 PRIMARY NULL NULL NULL NULL NULL NULL NULL No tables used
632
2 SUBQUERY t1 ALL NULL NULL NULL NULL 2 Using where
633
CREATE TABLE t2 (a CHAR(5) CHARACTER SET latin1 COLLATE latin1_general_ci);
634
INSERT INTO t2 VALUES (0xf6);
635
INSERT INTO t2 VALUES ('oe');
636
SELECT COUNT(*) FROM (SELECT DISTINCT a FROM t2) dt;
640
(SELECT DISTINCT a FROM t2 WHERE a='oe' COLLATE latin1_german2_ci) dt;
644
611
CREATE TABLE t1 (a INT, UNIQUE (a));
645
612
INSERT INTO t1 VALUES (4),(null),(2),(1),(null),(3);
646
613
EXPLAIN SELECT DISTINCT a FROM t1;