ALTER

Grokking SQL for Tech Interviews

Ask Author

Back to course home

0% completed

Vote For New Content

ALTER

Table of Contents

Contents are not accessible

In SQL, the ALTER statement is used to modify the structure of an existing database object, such as a table.

It allows you to add, modify, or drop columns, constraints, or other elements of a table without having to drop and recreate the entire table.

The basic syntax for the ALTER statement varies depending on the specific modification you want to make. Here are some examples.

To add a new column in a database table, you can use the ALTER command like this

ALTER TABLE table_name
ADD column_name data_type;

This statement adds a new column with the specified name and data type to the existing table.

Suppose we have an employees table with the column id, firstName, lastName as shown below:

by using ALTER, we can add a new column salary like this:

ALTER TABLE Employees
ADD salary INT;

After the query execution the Employee table will look like this:

.....

Like the course? Get enrolled and start learning!

Table of Contents

Contents are not accessible