用于从三个表中获取数据的SQL查询

Question

我有三张表如下

• 成绩 id，emp_id，area，dat

• calls_per_day id，emp_id，noofcalls，hotcalls，hotleads，dat

• sales_statistics_master id，emp_id，target，commitment，mnth，yrs

现在我想从以上三个表格中提取员工的数据，了解他的成就，noofcalls，hotcalls，hotleads perdayday兑换每月目标和承诺。

我正在使用以下查询。

SELECT  a.area, s.target,s.commitment,c.noofcalls,c.hotcalls,c.hotleads 
FROM   achievement as a, sales_statistics_master as s, calls_per_day as c 
WHERE  a.dat=CURDATE() AND 
       c.dat=CURDATE() AND 
       s.yrs= year(now()) AND 
       a.emp_id=s.emp_id AND
       a.emp_id=c.emp_id

Answer 1

使用（字段）连接。

select a.area, s.target,s.commitment,c.noofcalls,c.hotcalls,c.hotleads from
achievement as a join
sales_statistics_master as s using(emp_id) join
calls_per_day as c using(emp_id)
where a.dat=CURDATE() AND c.dat=CURDATE() AND s.yrs= year(now())