同事发来2个语句,说语句1跑得慢,语句2很快就出结果。一执行,果然很慢。仔细发现,2个语句不等价。 语句1: select l.*,o.object_name from v$locked_object l left join all_objects o on l.object_id=o.object_id;语句2: select l.*,o.object_name from
同事发来2个语句,说语句1跑得慢,语句2很快就出结果。一执行,果然很慢。仔细发现,2个语句不等价。
语句1:select l.*,o.object_name from v$locked_object l left join all_objects o on l.object_id=o.object_id; 语句2:
select l.*,o.object_name from v$locked_object l,all_objects o where l.object_id=o.object_id;
select l.*,o.object_name from v$locked_object l,all_objects o where l.object_id=o.object_id(+);
select l.*,(select o.object_name from all_objects o where l.object_id=o.object_id) from v$locked_object l;
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