mysql 表查询语句
mysql中查询语句的表名，是否可以动态选
出现在select语句中的select语句，称为子查询或内查询。
MySQL查询语句
SELECT a.DemandNO,IFNULL(countb,0)+IFNULL(countc,0) as 结果 from tb_dm_demand a LEFT JOIN
(SELECT DemandNO,COUNT(1) as countb from tb_dm_deduction GROUP BY DemandNO) b
ON a.DemandNO=b.DemandNO LEFT JOIN
(SELECT DemandNO,COUNT(1) as countc from tb_im_interview GROUP BY DemandNO) c
ON a.DemandNO=c.DemandNO ORDER BY DemandNO
