ALTER TABLE ADD Column

To add new column in existing table, ALTER TABLE is used with ADD action with following syntax

Syntax:

ALTER TABLE table_name 
ADD column_name data_type constraint;

In this statement:

• -First, you specify the name of the table, which you want to add the new column, after the ALTER TABLE clause.
• -Second, you specify the column name, data type, and its constraint.

Points to Remember:

• You cannot add a column that already exists in the table; trying to do so will cause an error.
• In addition, the ALTER TABLE ADD column statement adds the new column at the end of the table.  

How to add multiple columns in the existing table

Syntax:

ALTER TABLE table_name  
 ADD (column_name_1 data_type constraint, 
   column_name_2 data_type constraint,
    ...  
    column_name_n data_type constraint); 

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