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openGauss每日一练第16天:事物的使用

原创 秋天的最后一片枫叶 2021-12-18
327

1.以默认方式启动事务1,修改事务隔离级别,查看transaction_isolation
START TRANSACTION;


SET LOCAL TRANSACTION ISOLATION LEVEL READ COMMITTED READ ONLY;


show transaction_isolation;

2.以读写方式启动事务2,创建新表,修改事务为只读事务,查看transaction_read_only,并向表中插入记录
show transaction_isolation;


START TRANSACTION ISOLATION LEVEL repeatable read READ WRITE;


create table test(c1 char(10));


SET LOCAL TRANSACTION ISOLATION LEVEL READ COMMITTED READ ONLY;


show transaction_read_only;


insert into test values ('job');


3.启动事务3,对表进行增删改查,并用到创建savepoint,回滚savepoint和删除savepoint

show transaction_isolation;


CREATE TABLE t1(a int,b char(10));


START TRANSACTION;


INSERT INTO t1 VALUES (1,'job');
INSERT INTO t1 VALUES (2,'lizhang');


SAVEPOINT my_savepoint;


delete from t1 where a=1;


ROLLBACK TO SAVEPOINT my_savepoint;


update t1 set b='wang' where a=1;


RELEASE SAVEPOINT my_savepoint;


update t1 set b='wu' where a=2;


COMMIT;
SELECT * FROM t1;


4.清理数据
truncate table t1;
drop table t1;


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