SQL-Server/Access - Order BY 1,2?

I came across a query today,

我今天遇到一个问题，

SELECT col1,'yes' as col2  FROM myTable  
   WHERE col2=TRUE  
UNION  
SELECT col1,'no' as col2 FROM mytable  
   WHERE col2=FALSE  
ORDER BY 1,2  

I thought it would order by first column and then second but since a UNION is involved I am a bit unsure can someone explain the exact meaning of this query

我原以为它会按第一列和第二列排序，但由于涉及到UNION，我有点不确定是否有人能解释这个查询的确切含义

1 个解决方案

#1

SQL Server will union the results together (which is an implied select distinct) and then order the results by col1 then col2. In a union query, you can put an ORDER BY on the final select, which will sort the final result.

SQL Server将把结果合并在一起(这是一个隐含的select distinct)，然后通过col1然后col2对结果进行排序。在union查询中，您可以在final select上放置一个ORDER BY，它将对最终结果进行排序。