java - 尝试在 select 语句中连接列时出现未找到列异常

Question

我的java代码中有:

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。也许您想要/需要使用 CONCAT功能:

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