从条件中选择两个表中的两列

Question

我想

 SELECT table1.columnA FROM table1 + ORDER BY id DESC LIMIT 1; //to get last row

和

SELECT SUM(table2.columnB) FROM table2

然后我想做一个像

这样的减号

SELECT table1.columnA FROM table1 ORDER BY id DESC LIMIT 1 - SELECT SUM(table2.columnB) FROM table2

但它不起作用。

Answer 1

如果您想要的是从columnA中减去columnB总和之间的结果，请使用：

SELECT table1.id,table1.columnA -(select sum(columnB) from table2) as YourColumn
FROM Table1
ORDER BY table1.id desc LIMIT 1