sql distinct by two columns code example

Example 1: select count distinct multiple columns sql server

SELECT COUNT(DISTINCT (CHECKSUM(DocumentId,DocumentSessionId)) + CHECKSUM(REVERSE(DocumentId),REVERSE(DocumentSessionId)) )
FROM DocumentOutPutItems

Example 2: sql server select rows by distinct column

SELECT a.*
FROM emails a
INNER JOIN 
  (SELECT email,
    MIN(id) as id
  FROM emails 
  GROUP BY email 
) AS b
  ON a.email = b.email 
  AND a.id = b.id;

Example 3: select distinct on 2 columns

SELECT agent_code, ord_amount, cust_code, ord_num
FROM orders 
WHERE agent_code='A002';

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