一个多表嵌套查询的sql语句
select batch_no "批次号",get_id "分类" from (
select(
select plan1.batch_no from product_plan plan1 where plan1.item_no=(select head1.product_code from wo_head head1 where head1.order_no =bbb)) batch_no,
(select decode(get_id,'BUY','外购件','MAK','自制件','MB','未定') from item where item_no= aaa) get_id
from (select req.item_no aaa,req.order_no bbb from process_req req where req.status_id='C'and req.order_no in(select head.order_no from wo_head head where head.batch_no in (select batch_no from product_plan) or head.product_code in ( select item_no from product_plan )))) order by qty desc
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一.名词解释：
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SELECT k
from (
SELECT 'shanghai' AS k from DUAL
UNION ALL
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)
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......
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