The Effect of ALTER TABLE on Null and Default Value Attributes : Alter Table « Table Index « SQL / MySQL






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The Effect of ALTER TABLE on Null and Default Value Attributes

     
mysql>
mysql>
mysql> CREATE TABLE mytbl
    -> (
    ->     j INT,
    ->     c CHAR(1)
    -> );
Query OK, 0 rows affected (0.01 sec)

mysql>
mysql>
mysql> ALTER TABLE mytbl MODIFY j INT NOT NULL DEFAULT 100;
Query OK, 0 rows affected (0.01 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> SHOW COLUMNS FROM mytbl LIKE 'j';
+-------+---------+------+-----+---------+-------+
| Field | Type    | Null | Key | Default | Extra |
+-------+---------+------+-----+---------+-------+
| j     | int(11) | NO   |     | 100     |       |
+-------+---------+------+-----+---------+-------+
1 row in set (0.00 sec)

mysql>
mysql> drop table mytbl;
Query OK, 0 rows affected (0.00 sec)








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33.Alter table to add an index
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35.Alter table to Delete an Index
36.Alter table to add index
37.To drop an index with ALTER TABLE
38.Reduce the number of significant characters per index in the index to the first 16 characters
39.Add IGNORE to the statement, then use SELECT to have a look at the table contents to see how the duplicates ha
40.Change j from INT to BIGINT
41.MODIFY statement should specify the null and default value attributes explicitly
42.Redefine i to be NOT NULL, then try again
43.Change column definition