尝试连接select语句中的列时未找到列的异常

Question

我的java代码：

StringBuilder stringQuery = new StringBuilder("select product_id, type || '_' || price as info ");
SQLQuery q = createSQLQuery(stringQuery.toString());
 q.list();

我收到此错误：

Caused by: java.sql.SQLException: Column '' not found.

Answer 1

||是MySQL中的OR运算符，它不会连接type，'_'和price的值。您可能希望/需要使用CONCAT函数：

StringBuilder stringQuery = new StringBuilder("select product_id, CONCAT(type, '_', price) as info ");
//...