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CREATE TABLE t1 (A SERIAL);
INSERT INTO t1 VALUES (), (), ();
SELECT A from t1 ORDER BY A;
A
1
2
3
ALTER TABLE t1 ADD COLUMN b INT NOT NULL;
ERROR HY000: Either a DEFAULt value or NULL NULL description is required for a new column if table is not empty
SELECT A from t1 ORDER BY A;
A
1
2
3
SHOW CREATE TABLE t1;
Table Create Table
t1 CREATE TABLE `t1` (
`A` BIGINT NOT NULL AUTO_INCREMENT,
UNIQUE KEY `A` (`A`)
) ENGINE=InnoDB COLLATE = utf8_general_ci
ALTER TABLE t1 ADD COLUMN b INT DEFAULT 1 NOT NULL;
SELECT A,B from t1 ORDER BY A;
A B
1 1
2 1
3 1
DROP TABLE t1;
CREATE TABLE t1 (A SERIAL, b int);
INSERT INTO t1 VALUES (), (), ();
SELECT A,B from t1 ORDER BY A;
A B
1 NULL
2 NULL
3 NULL
ALTER TABLE t1 MODIFY COLUMN b int not null;
ERROR 01000: Data truncated for column 'b' at row 1
SELECT A,B from t1 ORDER BY A;
A B
1 NULL
2 NULL
3 NULL
SHOW CREATE TABLE t1;
Table Create Table
t1 CREATE TABLE `t1` (
`A` BIGINT NOT NULL AUTO_INCREMENT,
`b` INT DEFAULT NULL,
UNIQUE KEY `A` (`A`)
) ENGINE=InnoDB COLLATE = utf8_general_ci
ALTER TABLE t1 MODIFY COLUMN b int DEFAULT 42 NOT NULL;
SELECT A,B from t1 ORDER BY A;
A B
1 42
2 42
3 42
DROP TABLE t1;
CREATE TABLE t1 (col6 int not null);
INSERT INTO t1 VALUES (2);
SELECT * FROM t1;
col6
2
alter table t1 modify column col6 int not null;
select * from t1;
col6
2
drop table t1;
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