MySQL查询从具有相似列“ UP”的5张表中计算总和？
为此，请将UNIONALL与一起使用SUM()。让我们创建5个表-
mysql> create table DemoTable1977 ( UP int ); mysql> insert into DemoTable1977 values(10); mysql> insert into DemoTable1977 values(20); mysql> select * from DemoTable1977; +------+ | UP | +------+ | 10 | | 20 | +------+ 2 rows in set (0.00 sec) mysql> create table DemoTable1978 ( UP int ); mysql> insert into DemoTable1978 values(30); mysql> select * from DemoTable1978; +------+ | UP | +------+ | 30 | +------+ 1 row in set (0.00 sec) mysql> create table DemoTable1979 ( UP int ); mysql> insert into DemoTable1979 values(40); mysql> select * from DemoTable1979; +------+ | UP | +------+ | 40 | +------+ 1 row in set (0.00 sec) mysql> create table DemoTable1980 ( UP int ); mysql> insert into DemoTable1980 values(50); mysql> select * from DemoTable1980; +------+ | UP | +------+ | 50 | +------+ 1 row in set (0.00 sec) mysql> create table DemoTable1981 ( UP int ); mysql> insert into DemoTable1981 values(60); mysql> select * from DemoTable1981; +------+ | UP | +------+ | 60 | +------+ 1 row in set (0.00 sec)
这是一个查询，用于从5个表中计算总和，其中一个列名为“UP”-
mysql> select sum(TotalSum)
from (
select sum(UP) as TotalSum
from DemoTable1977
union all
select sum(UP)
from DemoTable1978
union all
select sum(UP)
from DemoTable1979
union all
select sum(UP)
from DemoTable1980
union all
select sum(UP)
from DemoTable1981
) tbl;这将产生以下输出-
+---------------+ | sum(TotalSum) | +---------------+ | 210 | +---------------+ 1 row in set (0.00 sec)