SQLiteException：在“FROM”附近：语法错误多个连接

Question

任何人都可以在这里查看我的查询是否有错误，这是我第一次尝试多个联接，下面是 logcat 错误。提前致谢

android.database.sqlite.SQLiteException：靠近“FROM”：语法错误 （代码 1 SQLITE_ERROR[1]）：，编译时：SELECT SUM（A.quantity）， A.ingredient, A.recipe, B.ingredient_type, B.measurement_name, C.id, D.plan_name, FROM QUANTITY AS A JOIN INGREDIENTS AS B ON A.ingredient = B.ingredient_name 按 A.recipe 加入计划食谱 = C.recipe_name 按 C.id 加入 MEAL_PLAN = D.plan_recipe 按 A.ingredient 分组 D.plan_name LIKE 在哪里？

代码

    public void loadIngredient() {
    shopList.clear();
    db = (new DatabaseManager(this).getWritableDatabase());
    String RECIPE_SEARCH = " SELECT SUM(A.quantity), A.ingredient, A.recipe, B.ingredient_type, B.measurement_name, C.id, D.plan_name, " +
            "FROM " + DatabaseManager.TABLE_QUANTITY + " AS A JOIN " + DatabaseManager.TABLE_INGREDIENTS +
            " AS B ON A.ingredient = B.ingredient_name" + " JOIN " + DatabaseManager.TABLE_PLAN_RECIPES + " AS C ON A.recipe = C.recipe_name " +
            " JOIN " + DatabaseManager.TABLE_MEAL_PLAN + " AS D ON C.id = D.plan_recipe GROUP BY A.ingredient";
    String selectQuery = "";
    selectQuery = RECIPE_SEARCH + " WHERE D.plan_name LIKE ?";
    c = db.rawQuery(selectQuery, new String[]{"%" + search + "%"});
    if (c.moveToFirst()) {
        do {
            Shopping_List shopping_list = new Shopping_List();
            shopping_list.setQuantity(c.getDouble(c.getColumnIndex("quantity")));
            shopping_list.setIngredient_name(c.getString(c.getColumnIndex("ingredient_name")));
            shopping_list.setIngredient_type(c.getString(c.getColumnIndex("ingredient_type")));
            shopping_list.setMeasurement_name(c.getString(c.getColumnIndex("measurement_name")));
            shopList.add(shopping_list);
        } while (c.moveToNext());
        c.close();
    }

}

Answer 1

您的代码中有几个问题。

第一个是逗号，必须在 D.plan_name 之后的变量 RECIPE_SEARCH 中删除，就在 FROM 子句之前。

第二个是WHERE 子句，必须在GROUP BY 子句之前。

3d 是您必须为查询返回的列 SUM(A.quantity) 设置别名，以便您可以通过该别名检索它，例如 quantity。

第四个是您的查询没有返回列ingredient_name，但我假设这是列A.ingredient，应该别名为ingredient_name。

所以改成这样：

public void loadIngredient() {
    shopList.clear();
    db = (new DatabaseManager(this).getWritableDatabase());
    String RECIPE_SEARCH = 
        "SELECT SUM(A.quantity) quantity, A.ingredient ingredient_name, A.recipe, B.ingredient_type, B.measurement_name, C.id, D.plan_name " +
        "FROM " + DatabaseManager.TABLE_QUANTITY + " AS A JOIN " + DatabaseManager.TABLE_INGREDIENTS + " AS B ON A.ingredient = B.ingredient_name " + 
        "JOIN " + DatabaseManager.TABLE_PLAN_RECIPES + " AS C ON A.recipe = C.recipe_name " +
        "JOIN " + DatabaseManager.TABLE_MEAL_PLAN + " AS D ON C.id = D.plan_recipe " +
        "WHERE D.plan_name LIKE ? GROUP BY A.ingredient";   
    c = db.rawQuery(RECIPE_SEARCH, new String[]{"%" + search + "%"});

    if (c.moveToFirst()) {
        do {
            Shopping_List shopping_list = new Shopping_List();
            shopping_list.setQuantity(c.getDouble(c.getColumnIndex("quantity")));
            shopping_list.setIngredient_name(c.getString(c.getColumnIndex("ingredient_name")));
            shopping_list.setIngredient_type(c.getString(c.getColumnIndex("ingredient_type")));
            shopping_list.setMeasurement_name(c.getString(c.getColumnIndex("measurement_name")));
            shopList.add(shopping_list);
        } while (c.moveToNext());
    }
    c.close();
    db.close();
}

此外，您的查询会返回您未在循环中使用的列，我没有将其删除，您可以将它们删除。