联表查询求和再算差值,求SQL
统计表1和表2相同客户号,然后求和,再对比表3金额差值
先将表1和表2数据合并,之后分组聚合算出总金额,之后select想要的结果字段即可
SELECT
t3.cust_no,t3.amt,t2.cust_no,t2.amt,t3.amt-t2.amt as balance
FROM
(SELECT
客户号 AS cust_no,
SUM(余额) AS amt
FROM tb3
GROUP BY
客户号) t3
LEFT JOIN(
SELECT
客户号 AS cust_no,SUM(余额) AS amt
FROM
(SELECT 客户号,余额 from tb1 union all SELECT 客户号,余额 from tb2) t
GROUP BY
t.客户号) t2
ON
t3.cust_no = t2.cust_no