openGauss每日一练第16天|课后作业

课程作业

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;
show transaction_isolation;
SET LOCAL TRANSACTION ISOLATION LEVEL repeatable read READ WRITE;
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

CREATE TABLE test (id int, name char(30));
BEGIN;
SET LOCAL TRANSACTION ISOLATION LEVEL READ COMMITTED READ ONLY;
show transaction_read_only;
INSERT INTO test VALUES (1, 'LiHua');
commit;

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

BEGIN;
CREATE TABLE table1(a int);
INSERT INTO table1 VALUES (1);
--建立保护点
SAVEPOINT my_savepoint;
INSERT INTO table1 VALUES (2);
--回滚到保护点
ROLLBACK TO SAVEPOINT my_savepoint;
--删除保护点
RELEASE SAVEPOINT my_savepoint;
INSERT INTO table1 VALUES (3);
COMMIT;

–查询表的内容，会同时看到1和3,不能看到2，因为2被回滚

SELECT * FROM table1;

4.清理数据

DROP TABLE table1;