SQL - Update

The UPDATE statement in SQL is used to modify existing records in a table. Here’s a detailed tutorial on how to use the UPDATE statement effectively.

Basic Syntax

UPDATE table_name
SET column1 = value1, column2 = value2, ...
WHERE condition;

Steps to Update Data

1. Specify the table name: Indicate the table that contains the data you want to update.
2. Set the new values: Use the SET clause to specify the columns and their new values.
3. Provide the condition: Use the WHERE clause to specify which rows should be updated. If you omit the WHERE clause, all rows in the table will be updated.

Examples

Assume you have a table named employees with columns first_name, last_name, age, and department.

Update the age of an employee named John Doe:

UPDATE employees
SET age = 31
WHERE first_name = 'John' AND last_name = 'Doe';

Update the age and department of an employee named Jane Smith:

UPDATE employees
SET age = 29, department = 'Sales'
WHERE first_name = 'Jane' AND last_name = 'Smith';

Increase the age of all employees by 1 year:

UPDATE employees
SET age = age + 1;