Which is correct syntax of ALTER TABLE?

Which is correct syntax of ALTER TABLE?

Syntax. The basic syntax of an ALTER TABLE command to add a New Column in an existing table is as follows. ALTER TABLE table_name ADD column_name datatype; The basic syntax of an ALTER TABLE command to DROP COLUMN in an existing table is as follows.

How do I change primary key in MySQL?

Syntax. The syntax to drop a primary key in MySQL is: ALTER TABLE table_name DROP PRIMARY KEY; table_name.

What is the syntax of primary key?

The syntax to create a primary key using the ALTER TABLE statement in SQL is: ALTER TABLE table_name ADD CONSTRAINT constraint_name PRIMARY KEY (column1, column2, column_n);

What does the ALTER TABLE clause do?

ALTER TABLE is used to add, delete/drop or modify columns in the existing table. It is also used to add and drop various constraints on the existing table.

How do I change primary key?

To set the primary key:

1. Open the database that you want to modify.
2. In the Navigation Pane, right click the table in which you want to set the primary key and, on the shortcut menu, click Design View.
3. Select the field or fields that you want to use as the primary key.

How do I change the primary key in a table in SQL Server?

Using SQL Server Management Studio

1. Open the Table Designer for the table whose primary key you want to modify, right-click in the Table Designer, and choose Indexes/Keys from the shortcut menu.
2. In the Indexes/Keys dialog box, select the primary key index from the Selected Primary/Unique Key or Index list.

What is primary key in a table?

A primary key is the column or columns that contain values that uniquely identify each row in a table. A database table must have a primary key for Optim to insert, update, restore, or delete data from a database table.

Which is the correct syntax to create a table in MySQL?

Use a CREATE TABLE statement to specify the layout of your table: mysql> CREATE TABLE pet (name VARCHAR(20), owner VARCHAR(20), species VARCHAR(20), sex CHAR(1), birth DATE, death DATE); VARCHAR is a good choice for the name , owner , and species columns because the column values vary in length.