php mysql 双条件排序,PHP-MySQL联合查询,按2个变量排序
每個表(表1和表2)具有其自己的DATETIME字段.
我正在嘗試捕獲兩個表的ID,并按其DATETIME字段對其進行排序.
例：
Table 1 Table 2
------------ -------------
id | datetime1 id | table1id | datetime2
------------------------ -----------------------
1 | 2014-09-21 20:31:26 1 | 2 | 2014-09-21 20:31:29
2 | 2014-09-21 20:31:27 2 | 3 | 2014-09-21 20:31:30
3 | 2014-09-21 20:31:28
Table 3
------------
id | user
------------------------
2 | phil
3 | nathalie
我的輸出未通過以下查詢正確排序：
SELECT *
FROM (
SELECT
1 AS selection,
table1.id, table1.datetime1,
table2.datetime2
table3.user
FROM Table1
LEFT OUTER JOIN table2
ON table1.id = table2.table1id
LEFT OUTER JOIN table3
ON table1.id = table3.id
UNION ALL
SELECT
2 AS selection,
table1.id, table1.datetime1,
table2.datetime2
table3.user
FROM Table1
INNER JOIN table2
ON table1.id = table2.table1id
INNER JOIN table3
ON table1.id = table3.id
) AS query
ORDER BY table1.datetime1 DESC, table2.datetime2 DESC
所需數據：
從表2 id：2,1,
從表1 id：3,2,1
因此：2、1、3、2、1
編輯
對于可能要處理冗長而復雜的MySQL請求的人們,請在PhpmyAdmin中嘗試一下！它會告訴您錯誤！
編輯
解決方法:
您真正需要做的是更仔細地考慮架構.考慮將日期時間列命名為相同的名稱,然后運行如下查詢-http://sqlfiddle.com/#!2/a3b4c/7/0
SELECT selection, id, datetimefoo, user FROM (
SELECT
1 AS selection,
table1.id, table1.datetimefoo,
table3.user
FROM table1
LEFT OUTER JOIN table2
ON table1.id = table2.table1id
LEFT OUTER JOIN table3
ON table1.id = table3.id
UNION
SELECT
2 AS selection,
table1.id, table1.datetimefoo,
table3.user
FROM table1
INNER JOIN table2
ON table1.id = table2.table1id
INNER JOIN table3
ON table1.id = table3.id
) AS T2
ORDER BY datetimefoo DESC
在SQL提琴中,這會產生與您要查找的結果更接近的結果.我仍然不確定為什么您需要在第二個查詢上使用INNER JOINS-在這里您不需要做什么.
SELECT * FROM (
SELECT
1 AS selection,
table1.id, table1.datetimefoo AS sort_date, -- alias on first table's date
table2.datetimebar,
table3.user
FROM table1
LEFT OUTER JOIN table2
ON table1.id = table2.table1id
LEFT OUTER JOIN table3
ON table1.id = table3.id
UNION
SELECT
2 AS selection,
table1.id, table1.datetimefoo,
table2.datetimebar AS sort_date, -- alias on second table's date
table3.user
FROM table1
INNER JOIN table2
ON table1.id = table2.table1id
INNER JOIN table3
ON table1.id = table3.id
) AS T2
ORDER BY sort_date DESC
標簽：php,sql,mysql
來源： https://codeday.me/bug/20191012/1898765.html
總結
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