标签归档：sql

使用left join替代not exists查询

使用 NOT EXISTS

SELECT  table1.column1,  table1.column2
      FROM table1
          WHERE NOT 
              EXISTS (
                    SELECT table2.column1, table2.column2
                    FROM table2
                    WHERE table2.column1= table1.column1
                    AND table2.location_id= 6
                )
      GROUP BY Barcode

使用 LEFT JOIN

SELECT  table1.column1,  table1.column2
   FROM table1
   LEFT JOIN table2
   ON table2.column1= table1.column1
     AND table2.location_id= 6
   WHERE table2.column1 is null
   GROUP By Barcode