update set where exists 多表更新 在mssql、MySQL、Oracle中分别用法

MySQL：
UPDATE ChgCfm t1
      INNER JOIN  tb_dz_file t2 ON t1.ID = t2.ID
      SET   t1.CfmStatus =0
      WHERE t1.CmfFile =''

SQLserver:

UPDATE t1   SET  t1.CfmStatus=0  FROM  ChgCfmRcd t1
     INNER JOIN tb_dz_file  t2  on t1.RcdID=t2.DzID WHERE t1.CmfFile=''

UPDATE t1   SET  t1.CfmStatus=0  FROM  ChgCfmRcd t1
       WHERE EXISTS ( SELECT 1 FROM tb_dz_file t2  WHERE t1.RcdID=t2.DzID AND t1.CmfFile='');

Oracle:

UPDATE ChgCfmRcd  t1 SET  t1.CfmStatus=0
       WHERE EXISTS ( SELECT  FROM tb_dz_file t2  WHERE t1.RcdID=t2.DzID AND t1.CmfFile='');
组合一个数：
 SELECT  CONCAT(SUBSTRING('0105',1,2),'01')