1 echo CREATE TABLE t1 (f1 INT , f2 VARCHAR (12));
2 CREATE TABLE t1 (f1 INT , f2 VARCHAR (12));
3 echo INSERT INTO t1 VALUES(1, 'ABCD');
4 INSERT INTO t1 VALUES(1, 'ABCD');
5 echo INSERT INTO t1 VALUES(2, 'NULL');
6 INSERT INTO t1 VALUES(2, 'NULL');
7 echo INSERT INTO t1 VALUES(3, NULL);
8 INSERT INTO t1 VALUES(3, NULL);
9 echo INSERT INTO t1 VALUES(4, 'ABCEF');
10 INSERT INTO t1 VALUES(4, 'ABCEF');
11 echo INSERT INTO t1 (f1) VALUES (5);
12 INSERT INTO t1 (f1) VALUES (5);
13 echo INSERT INTO t1 VALUES(6, 'ABCFF');
14 INSERT INTO t1 VALUES(6, 'ABCFF');
15 echo select * from t1;
17 echo select * from t1 where f2 is null;
18 select * from t1 where f2 is null;
19 echo select * from t1 where f2 is not null;
20 select * from t1 where f2 is not null;