Alter table to add primary key, add new column, change column, drop column : Alter Table « Table Index « SQL / MySQL






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Alter table to add primary key, add new column, change column, drop column

     
mysql> CREATE TABLE IF NOT EXISTS dishes
    -> (
    ->   id             INT             NOT NULL,
    ->   pattern        VARCHAR(25)     NOT NULL,
    ->   price          DECIMAL(6,2)
    -> );
Query OK, 0 rows affected (0.00 sec)

mysql>
mysql> EXPLAIN dishes;          # confirm the "dishes" table format
+---------+--------------+------+-----+---------+-------+
| Field   | Type         | Null | Key | Default | Extra |
+---------+--------------+------+-----+---------+-------+
| id      | int(11)      | NO   |     | NULL    |       |
| pattern | varchar(25)  | NO   |     | NULL    |       |
| price   | decimal(6,2) | YES  |     | NULL    |       |
+---------+--------------+------+-----+---------+-------+
3 rows in set (0.00 sec)

mysql>
mysql> ALTER TABLE dishes
    ->   ADD PRIMARY KEY(id),
    ->   ADD COLUMN code INT UNIQUE NOT NULL,
    ->   CHANGE pattern dish_pattern VARCHAR(25) NOT NULL,
    ->   DROP COLUMN price;
Query OK, 0 rows affected (0.01 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql>
mysql> EXPLAIN dishes;          # confirm the "dishes" table format
+--------------+-------------+------+-----+---------+-------+
| Field        | Type        | Null | Key | Default | Extra |
+--------------+-------------+------+-----+---------+-------+
| id           | int(11)     | NO   | PRI | NULL    |       |
| dish_pattern | varchar(25) | NO   |     | NULL    |       |
| code         | int(11)     | NO   | UNI | NULL    |       |
+--------------+-------------+------+-----+---------+-------+
3 rows in set (0.00 sec)

mysql> DROP TABLE dishes;       # delete this sample table
Query OK, 0 rows affected (0.00 sec)








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6.Alter table: drop primary and foreign key
7.Alter table: add primary key, foreign key and add column
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10.Alter table to change the order
11.Alter table to add column
12.Alter table to change column sequence
13.Alter table to add columns
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15.Alter table to drop foreign key
16.Alter table to add fulltext search
17.Changing the Table Design (ALTER TABLE)
18.Use ALTER TABLE to change the column type
19.The Effect of ALTER TABLE on Null and Default Value Attributes
20.Create the table and then set the initial sequence value with ALTER TABLE
21.Alter table to set the primary key start
22.ALTER TABLE statement modifies the table accordingly
23.Using ALTER TABLE command to add the names_num column to the cust_names table
24.Two ALTER TABLE statements can be combined
25.Alter table to add foreign key
26.Syntax for Altering a Column
27.Syntax for altering table and delete a Column
28.Storing Altered Character Strings
29.To drop a default value, use ALTER col_name DROP DEFAULT:
30.ALTER column to BINARY
31.Use the asterisk to try matching against the name ian or the alternative spelling, iain.
32.Specifying Multiple Alterations
33.Alter table to add an index
34.Alter table to add unique index
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