SQL Add Index Syntax

The SQL syntax for ALTER TABLE Add Index is

ALTER TABLE "table_name"
ADD INDEX " INDEX_NAME " (COLUMN_NAME)

Let's look at the example. Assuming our starting point is the "customer" table created in the CREATE TABLE section:

Table customer

Column Name	Data Type
First_Name	char(50)
Last_Name	char(50)
Address	char(50)
City	char(50)
Country	char(25)
Birth_Date	date

Assume we want to add an index on the "Country" column. To do this, we type in the following:

ALTER table customer ADD INDEX IDX_COUNTRY (Country);

Please note that using ALTER TABLE to add an index is not supported in Oracle or SQL Server.