MySQL lock table usage to prevent repeated data under concurrent conditions

Locktable read lock if a thread obtains the read lock on a table, the thread and all other threads can only read data from the table and cannot perform any write operations. Loc

Lock table read lock if a thread obtains the read lock on a table, the thread and all other threads can only read data from the table and cannot perform any write operations. Loc

Lock table read lock

If a thread acquires a read lock on a table, the thread and all other threads can only read data from the table and cannot perform any write operations.

Lock tables user read; // read the locked table

Unlock tables; // unlock

Lock tables user read local; // The local read locks the table. The insert statements of other threads are not blocked, and the update operation is blocked.

Lock table write lock

If a thread gets a write lock on a table, only the thread that owns the lock can read and write tables from the table. Other threads are blocked.

Lock tables user write; // write to lock the table

Unlock tables; // unlock

Usage instance in Yii

/**
* Single content status on the current day
*/
Public function getPointAready ($ marke, $ dayTime ){
$ Model = SysRun: model ()-> findByAttributes (array ('syr _ marking' => $ marke, 'syr _ daytime' => $ daytime ));
If (empty ($ model )){
// Table write lock
Yii: app ()-> db-> createCommand ()-> setText ("lock tables {sys_run} WRITE")-> execute ();
$ Model = new SysRun ();
$ Model-> syr_marking = $ marke;
$ Model-> syr_daytime = $ dayTime;
$ Model-> syr_val = 0;
$ Model-> syr_subval = 0;
$ Model-> save ();
// Unlock a table
Yii: app ()-> db-> createCommand ()-> setText ("unlock tables")-> execute ();
}
Return $ model;
}