openGauss每日一练第16天事务控制

事务是用户定义的一个数据库操作序列，这些操作要么全做要么全不做，是一个不可分割的工作单位.

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;
set local transaction isolation level read committed read only;
show transaction_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

start transaction isolation level repeatable read read write;
create table t1(a int);
start transaction isolation level repeatable read read only;
show transaction_read_only;
insert into t1 values (1);end;

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

start transaction isolation level repeatable read read write;
create table t1(a int);
insert into t1 values (1),(2);
update t1 set a=22 where a=2;
savepoint point1;
insert into t1 values(3);
rollback to savepoint point1; 
release savepoint point1;
end;
select *  from t1;

4.清理数据

drop table t1;