How to Update a Single Record in SQL Based on a Condition?

Last update on September 20 2025 13:31:07 (UTC/GMT +8 hours)

Update a Single Record

Write a SQL query to update a single record in a table based on a specific condition.

Solution:

-- Update the salary of an employee with EmployeeID = 1.
UPDATE Employees -- Specify the table to update.
SET Salary = 55000 -- Set the new value for the "Salary" column.
WHERE EmployeeID = 1; -- Apply the update only to the employee with ID 1.

Explanation:

1. Purpose of the Query :

The goal is to update the Salary of a specific employee in the Employees table.
This demonstrates how to use the UPDATE statement to modify existing data in a table based on a condition.

2. Key Components :

UPDATE Employees : Specifies the table where the update will occur.
SET Salary = 55000 : Defines the new value for the Salary column.
WHERE EmployeeID = 1 : Ensures that the update applies only to the employee with EmployeeID = 1.

3. Why use UPDATE? :

The UPDATE statement is used to modify existing records in a table, making it essential for maintaining accurate and up-to-date data.
For example, if an employee receives a raise, their salary can be updated in the database using this statement.

4. Real-World Application :

For example, in a company database, you might use this query to update the salary of an employee with EmployeeID = 1 to reflect a recent promotion or adjustment.

Additional Notes:

WHERE clause is critical to ensure that updates are applied only to the intended rows.
Scenarios where updating a single record is appropriate, such as:

Adjusting an employee's salary after a promotion or raise.
Correcting erroneous data in a specific record.

Important Considerations :

Always include a WHERE clause to avoid unintentionally updating all rows in the table.
Verify that the condition in the WHERE clause uniquely identifies the target record.

For more Practice: Solve these Related Problems:

Write a SQL query to update a single record in the 'employees' table, setting a column's value based on a subquery that retrieves data from the 'salaries' table.
Write a SQL query to update a single record using a CASE expression to conditionally modify a column's value.
Write a SQL query to update a single record where the WHERE clause involves multiple conditions combined with AND/OR operators.
Write a SQL query to update a single record in one table by joining it with another table to determine the new value.
Write a SQL query to update a single record by incrementing a numeric column based on its current value using an arithmetic operation.

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