Oracle开发总结
对于oracle来说是要有DML操作，就会记录在undo中，就会产生lockSQL基础非关联子查询：子查询中并没有上一级表字段的介入select * from emp where deptno = (select deptno from dept where loc = 'NEW YORK')关联子查询：子查询和上一级表字段进行关联查询select e.*,(select d.loc from d...
