Lock Types and Lock Levels
This section describes 2 types of locks: Read Lock (Shared Lock) and Write Lock (Exclusive Lock), and 3 levels of locks: Table Lock, Row Lock, and Column Lock.
There are two types of locks:
- Read Lock - The locked data is reserved for read by the current session.
Other sessions can read the locked data. But they can not write (update) the locked data.
A read lock is also called a shared lock.
- Write Lock - The locked data is reserved for write by the current session.
Other sessions can not read and write the locked data. A write lock is also called
an exclusive lock.
There are three levels of locks:
- Table Lock - The lock is set at the table level. All rows in the locked table
- Row Lock - The lock is set at the row level. Some rows of a table are locked.
But other rows are not locked.
- Column Lock - The lock is set at the column level. Some columns of a row are locked.
But other columns are not locked.
Last update: 2015.
Table of Contents
About This Book
Introduction of SQL
MySQL Introduction and Installation
Introduction of MySQL Programs
Perl Programs and MySQL Servers
PHP 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
Using SELECT to Query Database
Transaction Management and Isolation Levels
►Locks Used in MySQL
►Lock Types and Lock Levels
Table Level Locks in MySQL
Row Level Locks in MySQL
Defining and Calling Stored Procedures
Variables, Loops and Cursors Used in Stored Procedures
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