请问以下两中SQL语句,哪种写法更规范,更省时间?
select BaseCate from KnowledgeBaseCate where PareBase= (select PareBase from KnowledgeBaseCate where BaseCate='BCD')
select KBC_1.BaseCate from KnowledgeBaseCate KBC_1, KnowledgeBaseCate KBC_2 where KBC_1.PareBase=KBC_2.PareBase and KBC_1.BaseCate='BCD'
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比较两SQL语句
请问以下两中SQL语句,哪种写法更规范,更省时间? select BaseCate from KnowledgeBaseCate where PareBase= (select PareBase from KnowledgeBaseCate where BaseCate='BCD') select KBC_1.BaseCate from KnowledgeBaseCate KBC_1, KnowledgeBaseCate KBC_2 where KBC_1.PareBase=KBC_2.Pare
--给你提供一个吧
select BaseCate
from KnowledgeBaseCate a
where exists (
select 1 from KnowledgeBaseCate b
where b.BaseCate='BCD'
and a.PareBase = b.PareBase
)