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sqlsql-servert-sqlsql-server-2008stored-procedures

Get MAX value of a BIT column

I have a SELECT request with 'inner join' in the joined table is a column with bit type.

I want to select 1 if in the joined table is at most one value with 1. If it is not the case the value will be 0.

So If I have:

PERSID | NAME
1      |  Toto
2      |  Titi
3      |  Tata

And the second table

PERSID | BOOL
1      |  0
1      |  0
2      |  0
2      |  1

I would like to have for result 

Toto -> 0
Titi -> 1
Tata -> 0

I try this:

SELECT 
     sur.*
    ,MAX(bo.BOOL)    

    FROM SURNAME sur              
    INNER JOIN BOOL bo
    ON bo.IDPERS = sur.IDPERS

But MAX is not available on BIT column.. So how can I do that?

Thanks,

Solution

  • you can cast it to an INT, and even cast it back to a BIT if you need to

    SELECT 
     sur.*
    ,CAST(MAX(CAST(bo.BOOL as INT)) AS BIT)
    FROM SURNAME sur              
    INNER JOIN BOOL bo
    ON bo.IDPERS = sur.IDPERS