SQL count + join 抛出语法错误，但没有计数也能正常工作

Question

我在以下查询中遇到奇怪的语法错误：

SELECT COUNT (*) 
FROM a 
JOIN b ON a.id = b.a_id

但是没有 COUNT 的查询就像一个魅力：

SELECT * 
FROM a 
JOIN b ON a.id = b.a_id

添加 INNER、LEFT 等 JOIN 规范 - 没有帮助。

The syntax error doesn't specify exactly what's wrong, just provides certain codes: [42000][1064]

我该如何解决？

编辑：

这里是：

SELECT COUNT(customers.*) 
FROM customers 
JOIN customer_behaviour ON customers.id = customer_behaviour.customer_id

删除COUNT使其完全有效。这真的很奇怪！

Answer 1

删除 COUNT 和 (*) 之间的 space:

SELECT COUNT(*) FROM a JOIN b ON a.id = b.a_id 
    -- COUNT (*)

DBFiddle Demo

编辑：

SELECT COUNT(customers.*) 
FROM customers 
JOIN customer_behaviour 
  ON customers.id = customer_behaviour.customer_id

-- should be    
SELECT COUNT(*) 
FROM customers 
JOIN customer_behaviour 
  ON customers.id = customer_behaviour.customer_id

-- or
SELECT COUNT(customers.id) 
FROM customers 
JOIN customer_behaviour 
  ON customers.id = customer_behaviour.customer_id

编辑 2

Now, can I add DISTINCT to it? Seems like using COUNT (DISTINCT ...) starts throwing the error again!

定义列名即可：

SELECT COUNT(DISTINCT table_name.column_name) 
FROM customers 
JOIN customer_behaviour 
  ON customers.id = customer_behaviour.customer_id

SQL count + join 抛出语法错误，但没有计数也能正常工作

SQL count + join throws syntax error, but works ok without count

mysql

sql

mysql-error-1064

编辑：

编辑：

编辑 2