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

I came across a query today,

SELECT col1,'yes' as col2  FROM myTable  
   WHERE col2=TR开发者_StackOverflow社区UE  
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

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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.