通过作为JOIN查询一部分的ID进行过滤

Question

我正在处理一个有很多连接的查询。返回的数据是正确的：

SELECT
  cmb.item_id,
  cmba.field_id,
  cmba.attr_val,
  cmba.upd_dtt,
  cmba.upd_usr
FROM contract_member_brg cmb
INNER JOIN contract_member_brg_attr cmba
  ON (cmb.item_id = cmba.item_id) where  cmb.item_id=8086
UNION
SELECT
  cmb.item_id,
  ca.field_id,
  ca.attr_val,
  ca.upd_dtt,
  ca.upd_usr
FROM contract_member_brg cmb 
INNER JOIN contract_attr ca 
  ON (cmb.contract_item_id = ca.item_id) 
WHERE ca.field_id IN (413) and cmb.item_id=8086
UNION
SELECT
  cmb.item_id,
  91,
  m.item_name,
  m.upd_dtt,
  m.upd_usr
FROM contract_member_brg cmb
INNER JOIN contract_attr ca
  ON (cmb.contract_item_id = ca.item_id
  AND ca.field_id = 234)
INNER JOIN mfr m
  ON (ca.attr_val = m.item_pk);

我正在尝试过滤特定的item_id：

我已尝试使用不同别名的WHERE子句。

在哪里可以为此查询添加过滤器，以便我只能在此select语句中返回特定的item_id？

Answer 1

使您的整个查询成为子查询并对其进行过滤：

select * from 
(SELECT
  cmb.item_id,
  cmba.field_id,
  cmba.attr_val,
  cmba.upd_dtt,
  cmba.upd_usr
FROM contract_member_brg cmb
INNER JOIN contract_member_brg_attr cmba
  ON (cmb.item_id = cmba.item_id) where  cmb.item_id=8086
UNION
SELECT
  cmb.item_id,
  ca.field_id,
  ca.attr_val,
  ca.upd_dtt,
  ca.upd_usr
FROM contract_member_brg cmb 
INNER JOIN contract_attr ca 
  ON (cmb.contract_item_id = ca.item_id) 
WHERE ca.field_id IN (413) and cmb.item_id=8086
UNION
SELECT
  cmb.item_id,
  91,
  m.item_name,
  m.upd_dtt,
  m.upd_usr
FROM contract_member_brg cmb
INNER JOIN contract_attr ca
  ON (cmb.contract_item_id = ca.item_id
  AND ca.field_id = 234)
INNER JOIN mfr m
  ON (ca.attr_val = m.item_pk)
) a
where item_id = 'whatevs';

Here is an example to demonstrate