MySQL的隔離級別
| 級別 | 標(biāo)志 | 值 | 描述 |
|---|---|---|---|
| 讀未提交 | READ-UNCOMMITTED | 0 | 存在臟讀、不可重復(fù)讀、幻讀的問題 |
| 讀已提交 | READ-COMMITTED | 1 | 解決臟讀的問題庆揪，存在不可重復(fù)讀境析、幻讀的問題 |
| 可重復(fù)讀 | REPEATABLE-READ | 2 | mysql 默認(rèn)級別，解決臟讀咆槽、不可重復(fù)讀的問題陈轿，存在幻讀的問題 |
| 序列化 | SERIALIZABLE | 3 | 解決臟讀、不可重復(fù)讀秦忿、幻讀麦射，可保證事務(wù)安全，但完全串行執(zhí)行灯谣，性能最低 |
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我們可以通過以下命令 查看/設(shè)置 全局/會話 的事務(wù)隔離級別
mysql5.x
SELECT @@global.tx_isolation, @@tx_isolation;
one.PNG
mysql8.x
SELECT @@global.transaction_isolation, @@transaction_isolation;
two.PNG
mysql5.x修改回話隔離級別（才可以操作數(shù)據(jù)表的）
SET tx_isolation = 0;
set @@session.tx_isolation = 0;
SET tx_isolation = 'READ-UNCOMMITTED';
set @@session.tx_isolation = 'READ-UNCOMMITTED';
SET tx_isolation = 1;
set @@session.tx_isolation = 1;
SET tx_isolation = 'READ-COMMITTED';
set @@session.tx_isolation = 'READ-COMMITTED';
SET tx_isolation = 2;
set @@session.tx_isolation = 2;
SET tx_isolation = 'REPEATABLE-READ';
set @@session.tx_isolation = 'REPEATABLE-READ';
SET tx_isolation = 3;
set @@session.tx_isolation = 3;
SET tx_isolation = 'SERIALIZABLE';
set @@session.tx_isolation = 'SERIALIZABLE';
mysql8.x修改回話隔離級別（才可以操作數(shù)據(jù)表的）
SET transaction_isolation = 0;
set @@session.transaction_isolation = 0;
SET transaction_isolation = 'READ-UNCOMMITTED';
set @@session.transaction_isolation = 'READ-UNCOMMITTED';
SET transaction_isolation = 1;
set @@session.transaction_isolation = 1;
SET transaction_isolation = 'READ-COMMITTED';
set @@session.transaction_isolation = 'READ-COMMITTED';
SET transaction_isolation = 2;
set @@session.transaction_isolation = 2;
SET transaction_isolation = 'REPEATABLE-READ';
set @@session.transaction_isolation = 'REPEATABLE-READ';
SET transaction_isolation = 3;
set @@session.transaction_isolation = 3;
SET transaction_isolation = 'SERIALIZABLE';
set @@session.transaction_isolation = 'SERIALIZABLE';
