Question

我的查询如下：

SELECT cp.p_id AS p_id
  ,cp.p_id AS pk
  ,cp.name_first AS name_first
  ,cp.name_last AS name_last
  [...]
FROM tbl_E AS cp
INNER JOIN tbl_B, tbl_C, tbl_A, tbl_D AS cpr
WHERE cp.p_id = tbl_C.p_id
  AND tbl_C.sp_id = tbl_A.vsp_id
  AND tbl_B.p_id = cp.p_id
  AND cpr.pr_id = tbl_A.pr_id
  AND (
    cp.p_id = 339066
    OR cp.p_id = 103688
    OR cp.p_id = 321496
    )
GROUP BY cp.p_id
ORDER BY name_last ASC LIMIT 0,1000;

我希望得到3行，但我得到的行少于3行，因为tbl_C.p_id不包含所有的cp.p_id。如何更改查询以获得正好3行？

感谢。

Answer 1

这是因为您正在进行INNER JOIN ...将其更改为LEFT OUTER JOIN，如下所示

SELECT cp.p_id AS p_id
  ,cp.p_id AS pk
  ,cp.name_first AS name_first
  ,cp.name_last AS name_last
  [...]
FROM tbl_E AS cp
LEFT JOIN tbl_B ON tbl_B.p_id = cp.p_id
LEFT JOIN tbl_C ON cp.p_id = tbl_C.p_id
LEFT JOIN tbl_A ON tbl_C.sp_id = tbl_A.vsp_id
LEFT JOIN tbl_D AS cpr ON cpr.pr_id = tbl_A.pr_id
WHERE 
    cp.p_id IN (339066,103688,321496)
GROUP BY cp.p_id
ORDER BY cp.name_last 
LIMIT 0,1000;

具有空值的复杂mysql内连接查询

1 个答案: