Dapper.net“where ... in”查詢不適用於PostgreSQL

Question

以下查詢始終生成錯誤“42601：語法錯誤在或接近”$ 1“ ”。

connection.Query<CarStatsProjection>(
                @"select manufacturer, model, year, AVG(price) as averageprice, AVG(miles) as averagemiles, COUNT(*) as count
                        from products
                        where manufacturer IN @manufacturers 
                            AND model IN @models
                            AND year IN @years
                        group by manufacturer, model, year",
                new { manufacturers = new[] { "BMW", "AUDI" }, 
                      models = new[] { "M4", "A3" }, 
                      years = new[] { 2016, 2015 } });

我通過在下面創建一個方法並在內部調用它來構建SQL查詢來解決這個問題。 想知道Dapper是否可以使用對象參數來處理這個問題嗎？

 public static string ToInSql(this IEnumerable<object> values)
    {
        var flattened = values.Select(x => $"'{x}'");
        var flatString = string.Join(", ", flattened);

        return $"({flatString})";
    }

Answer 1

PostgreSQL IN運算符不支持數組（或任何其他集合）作為參數，只支持普通列表（使用ToInSql方法生成的ToInSql ），對於PostgreSQL，您需要使用ANY運算符，如下所示：

SELECT manufacturer, model, year, AVG(price) as averageprice, AVG(miles) as averagemiles, COUNT(*) as count
FROM products
WHERE manufacturer = ANY(@manufacturers)
AND model = ANY(@models)
AND year = ANY(@years)
GROUP BY manufacturer, model, year