我如何在android sqlite中编写连接查询？

Question

嗨，我是android新手。我想在sqlite中编写join连接的查询。我的代码是 -

public Cursor SearchCategory(SQLiteDatabase db){
        //return  db.query("category_master", null, "status = 'Active'", null, null, null, null);

        String Category_Sql = " select category_master.*,count(*) as cnt from product_master " +
                            "   left join category_master on product_master.category_id = category_master.category_id " +
                            "   where category_master.status = 'Active' group by category_master.category_id having cnt > 0 ";
        return db.query(Category_Sql);
    }

但它会产生错误。我哪里错了？

Answer 1

如果您能引用错误描述，那将会有更多帮助。

首先尝试在Portable SQLite explorer

中运行查询

Answer 2

你可以使用rawQuery

db.rawQuery("Select a.column1,b.column1 FROM table1 a JOIN table2 b ON a._id=b._id", null);

它应该有用