Default transaction isolation level in Mysql,oracle,sql server view, change

READ UNCOMMITTED (the lowest level of isolation transaction, only guaranteed not to read physically corrupted data)

Read Committed (the default level of the database engine)

REPEATABLE READ

Serializable (the highest level of isolation transactions, complete isolation between transactions)

Can be serialized more rigorous, high level;

Mysql

MySQL default transaction level is ' Repeatable-read ', which is repeatable read

1. View the current session isolation level

SELECT @ @tx_isolation;

2. View the current isolation level of the system

SELECT @ @global. tx_isolation;

3. Set the current session isolation level

Set session transaction Isolatin level repeatable read;

4. Set the current isolation level of the system

Set global transaction ISOLATION level repeatable read;

Oracle

The Oracle database supports both transaction isolation levels of Read COMMITTED and serializable.

The default system transaction isolation level is read COMMITTED, which reads committed

1. View the system default transaction isolation level, which is also the current session isolation level

--Create a transaction first
Declare
trans_id Varchar2 (100);
Begin
trans_id: = dbms_transaction.local_transaction_id (TRUE);
End

--View Transaction ISOLATION LEVEL

SELECT S.sid, s.serial#,

Case Bitand (T.flag, POWER (2, 28))
When 0 Then ' READ COMMITTED '
ELSE ' SERIALIZABLE '
END as Isolation_level
From V$transaction t
JOIN v$session s on t.addr = s.taddr and S.sid = Sys_context (' USERENV ', ' Sid ');

SQL Server

The default system transaction isolation level is read Committed, which reads committed

1. View the current isolation level of the system

DBCC useroptions

Isolation level The value of this item is both the current isolation levels setting

2. Set the current isolation level of the system

SET TRANSACTION Isolation level Read uncommitted;

Where READ uncommitted is the value you want to set

Default transaction isolation level in Mysql,oracle,sql server view, change