Skip to content

UPDATE statement

Purpose of the UPDATE Statement

The UPDATE statement modifies existing records in a table. It allows developers to change the values of one or more columns in a specific row or set of rows based on certain conditions.

Advantages and Disadvantages of Using the UPDATE Statement:

Trade-offs Description
Advantages - Allows for updating existing data without the need to delete and re-insert records.
- Provides flexibility in modifying specific columns or rows based on specified conditions.
- Can be used in conjunction with WHERE clause to update only selected rows, reducing unnecessary updates and improving performance.
- Supports bulk updates, allowing multiple rows to be modified in a single statement.
Disadvantages - Incorrectly formulated UPDATE statements can lead to unintended data changes or data loss.
- Lack of proper WHERE clause can result in updating all rows in a table, potentially causing data corruption or performance issues.
- May cause locking and contention issues in high-concurrency environments, impacting the performance of other queries accessing the same table.

Syntax of an UPDATE Statement:

Option Description
UPDATE table_name This clause specifies the name of the table you want to modify.
SET column_name1 = value1, column_name2 = value2, ... This clause defines which columns you want to update and their corresponding new values. You can update multiple columns by separating them with commas.
WHERE condition (optional) This clause specifies a condition that filters which rows in the table will be affected by the update. If omitted, all rows in the table will be updated.
UPDATE table_name
SET column1 = value1, column2 = value2, ...
[WHERE condition];

In this example, the statement does the following:

  • Modifies the salary column for employees in the ‘Sales’ department.

  • Increases the salary of each employee by 10% (salary * 1.1).

UPDATE employees
SET salary = salary * 1.1
WHERE department = 'Sales';

Fundamental SQL links:

Get expert help

If you need assistance, visit the community forum for comprehensive and free database knowledge, or contact our Percona Database Experts for professional support and services.


Last update: 2024-06-21