PostgreSQL-UNION與Order by 沖突

問題描述

union 連接的兩個sql 都包含 order

SELECT <property1>, <property2>
FROM <table1> 
ORDER BY <condition> LIMIT 1

UNION  ALL

SELECT <property1>, <property2>
FROM <table2> 
WHERE <condition> ORDER BY <condition> LIMIT 1;

錯誤

ERROR:  syntax error at or near "union"
LINE 2: union all
        ^
********** 錯誤 **********

ERROR: syntax error at or near "union"
SQL 狀態: 42601
字符:149

 

解決方法

我找了很多資料，試了很多方法，都不行，最后是這樣解決的

(SELECT <property1>, <property2>
FROM <table1> 
ORDER BY <condition>)

UNION  ALL

(SELECT <property1>, <property2>
FROM <table2> 
WHERE <condition> ORDER BY <condition>);

注意必須是 union all，不能是 union。

 

 

 

參考資料：

https://stackoverflow.com/questions/37352296/sql-union-all-with-order-by-and-limit-postgresql