MySQL 1054 Error Unknown column ... in ' ON clause '

ERROR 1054 (42S22): Unknown column ... in ' ON clause '

Reason:

To MySQL5.0 a Bug, enclose the combined table in parentheses :

Example :

SQL code

2. select  ( c.id, a.id, b.id)  from a  a, b b left join c c on c.a_id  = a.a_id and c.b_id = b.b_id  

The execution of this sentence should be error-free, but MySQL 5 execution will go wrong.

Because there is a bug under MySQL, it is necessary to enclose the combined table in parentheses:

SQL code

2. select  ( c.id, a.id, b.id)  from  (A  A, B B)  left join c c on c.a_id  = a.a_id and c.b_id = b.b_id  

But HQL generation is such a statement, how to do? We can change the way HQL is written to generate another SQL statement to avoid errors in this bug

Turn select (C.id, a.ID, b.id) from c c to left join C.A A to a left join C.B b

It will generate

SQL code

1. SELECT (c.id, a.ID, b.id) from a-a left join B-B left join C-C on c.a_id = a.a_id and c.b_ id = b.b_id

In this case, MySQL will not go wrong.

MySQL 1054 Error Unknown column ... in ' ON clause '