从加入中选择时出错

Question

有谁知道我从这个查询中收到错误的原因：

SELECT COUNT(*) 
FROM individual AS i LEFT JOIN establishment AS e USING establishment_id
WHERE i.bla = e.bla;

mysql-workbench在第1行的establishment_id下给了一条波浪线，并报告了语法错误，但我不确定为什么会收到此错误。

Answer 1

我认为你需要括号：

SELECT COUNT(*) 
FROM individual AS i LEFT JOIN establishment AS e USING (establishment_id)
WHERE i.bla = e.bla;

Answer 2

试试这个

SELECT COUNT(*) 
FROM individual AS i LEFT JOIN establishment AS e USING establishment_id
on i.bla = e.bla;