我的 sql 查询工作正常，直到我尝试添加绝对最后一行。我怎样才能让那部分工作？
INSERT INTO posts (ssp_order, ssp_id, ssp_ss_id, ssp_c_id)
SELECT COALESCE(MAX(ssp_order),0)+1 ,
" . $sspid . "," . $ssid . "," . $cid . "
FROM posts
WHERE ssp_ss_id = " . $ssid . "
ON DUPLICATE KEY UPDATE
ssp_status = 0,
ssp_order = SELECT COALESCE(MAX(ssp_order),0)+1 FROM posts
(请不要担心里面变量的安全性)
最佳答案
引用 select 语句中使用的表而不是使用子查询
INSERT INTO posts (ssp_order, ssp_id, ssp_ss_id, ssp_c_id)
SELECT maxssporder ,sspid,ssid,cid from
(SELECT COALESCE(MAX(ssp_order),0)+1 as maxssporder,
" . $sspid . " as sspid," . $ssid . " as ssid," . $cid . " as cid
FROM posts p
WHERE ssp_ss_id = " . $ssid . ") q
ON DUPLICATE KEY UPDATE
ssp_status = 0,
ssp_order = q.maxssporder
关于mysql - 在 key 更新时选择最大合并？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/46578068/