Update Query In SQL

How do you modify existing data in a SQL table?

An UPDATE query in SQL is used to modify existing data within a table. It allows you to change values in specific rows based on conditions. This is a fundamental operation for maintaining and updating data in a database.

Description

-- Update the customer's address where the customer ID is 123
UPDATE Customers
SET Address = '123 Main St', City = 'Anytown'
WHERE CustomerID = 123;

-- Example with multiple updates and a condition
UPDATE Orders
SET OrderStatus = 'Shipped'
WHERE OrderID IN (101, 102, 103) AND CustomerID = 456;

Common Mistakes

• Forgetting the WHERE clause: Updating all rows without a WHERE clause can lead to unintended data changes across the entire table.
• Incorrect data types in the SET clause: Ensure that the values you're updating match the data types of the columns.
• Typos in table or column names: Carefully check for typos in the table and column names to avoid errors.
• Missing or incorrect conditions in the WHERE clause: If the WHERE clause is not correctly specified, the update might not target the intended rows.