SQL query to update list of records by looping through a table records and check some logic?

I do not want to use cursors for performance reasons. Input Parameters for stored procedure: arg1, arg2,arg3 & arg4 For example: Table A > A1 Column and A2 Column, Table B > B1 Column (A.A1 <=>B.B1) foreign n primary key relation and B2 Column.

I want to update A.A2 value based on the following if condition,

if(arg1 == B.B2 && arg2 == B.B2)
{
   Update A set A.A2 = 1 where A.A1 = arg4
}
else{ 
if(arg1 == 1 && arg3 == B.B2){
 Update A set A.A2 = 0 where A.A1 = arg4
}

}

this is simple for one record but the Table A has 1000's records 开发者_StackOverflowthat match A.A1 = arg4 so i have to apply the above logic or case for all records and want to avoid using cursors...how do i do it?

---

Try the below query.

 UPDATE tmp
 SET tmp.A2 =
    (CASE WHEN (tmp1.B2 == arg1 && tmp1.B2 == arg2) THEN 1 WHEN (arg1 == 1 && tmp1.B2 == arg3) THEN 0 ELSE tmp.A2)
 FROM
     A tmp
 INNER JOIN
     B tmp1
        ON tmp.A1 = tmp1.B1
 WHERE
      tmp.A1 = arg4

Hope this Helps!!

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In general, non-specific SQL-92 you could do this:

UPDATE A
SET A.A2 = CASE WHEN B.B2 IN (@Arg1,@Arg2) THEN 1
            WHEN @arg1 = 1 AND B.B2 = @arg3 THEN 0 END
FROM A
JOIN B ON A.A1=B.B1
WHERE A.A1 = @arg4

You may need an ELSE before END if you don't want any values falling through (without the ELSE it would set A.A2 to NULL).