MySQL Tutorials - Herong's Tutorial Examples

∟Using DML to Insert, Update and Delete Records

∟UPDATE - Statement to Update Records in Tables

This section provides a tutorial example on how to use UPDATE statements to update records stored in tables.

An update statement allows you to update columns of existing rows of an existing table. The syntax of an update statement is:

UPDATE tbl_name SET column=expression, column=expression, ...
   [WHERE clause]

If executed, all rows that satisfy the condition in the where clause will be updated. Each specified column will be assigned with the value resulting from the specified expression.

Notes:

• Expressions are evaluated and resulting values are assigned to columns sequentially from left to right.
• Newly assigned values in previous columns can be used in later expressions.
• If no "where clause" is specified, all rows will be updated.

Here is an example SQL code, UpdateRows.sql, showing you how to update rows in an existing table:

-- UpdateRows.sql
-- Copyright (c) 1999 HerongYang.com. All Rights Reserved.
--
DROP TABLE IF EXISTS User;
CREATE TABLE User (Login VARCHAR(8), Password CHAR(8));
INSERT INTO User VALUES ('herong','8IS3KOX');
INSERT INTO User (Login) VALUES ('mike');
UPDATE User SET Password = 'IMCIAUS' WHERE Login = 'mike';
UPDATE User SET Login = CONCAT(Login,'_'),
   Password = CONCAT(Password,CHAR_LENGTH(Login));
SELECT 'User table:' AS '---';
SELECT * FROM User;

If you run the code, you will get:

---
User table:
Login   Password
herong_ 8IS3KOX7
mike_   IMCIAUS5

The output looks alright to me.

Table of Contents

 About This Book

 Introduction of SQL

 MySQL Introduction and Installation

 Introduction of MySQL Programs

 PHP Programs and MySQL Server

 Perl Programs and MySQL Servers

 Java Programs and MySQL Servers

 Datatypes and Data Literals

 Operations and Expressions

 Character Strings and Bit Strings

 Commonly Used Functions

 Table Column Types for Different Types of Values

 Using DDL to Create Tables and Indexes

►Using DML to Insert, Update and Delete Records

 INSERT INTO - Statement to Insert Records to Tables

►UPDATE - Statement to Update Records in Tables

 UPDATE with Joined Tables

 DELETE FROM - Statement to Delete Records from Tables

 Using SELECT to Query Database

 Window Functions for Statistical Analysis

 Use Index for Better Performance

 Transaction Management and Isolation Levels

 Locks Used in MySQL

 Defining and Calling Stored Procedures

 Variables, Loops and Cursors Used in Stored Procedures

 System, User-Defined and Stored Procedure Variables

 MySQL Server Administration

 Storage Engines in MySQL Server

 InnoDB Storage Engine - Primary and Secondary Indexes

 Performance Tuning and Optimization

 Bulk Changes on Large Tables

 MySQL Server on macOS

 Installing MySQL Server on Linux

 Connection, Performance and Second Instance on Linux

 Archived Tutorials

 References

 Full Version in PDF/EPUB

UPDATE - Statement to Update Records in Tables - Updated in 2023, by Herong Yang