LEFT JOIN 数据库左连接查询SQL



-- 普通查询
SELECT T1.NAME , T2.ORDERNO
  FROM TABLE_NAME1 T1 , TABLE_NAME T2
 WHERE T1.ID = T2.T1_ID
   AND T1.STATUS = '1';
-- LEFT JOIN查询
SELECT T1.NAME , T2.ORDERNO
  FROM TABLE_NAME1 T1
  LEFT JOIN TABLE_NAME T2
  ON T1.ID = T2.T1_ID
  AND T1.STATUS = '1';
注释:LEFT JOIN 左连接查询会以主表为查询主体,查询出另外一张表相对应的数据行,即使没有数据也会返回空的数据行!