C# - 如何从 sql 中捕获多个计数答案

【问题标题】：C# - How to capture multi count from sqlC# - 如何从 sql 中捕获多个计数
【发布时间】：2021-08-20 16:27:11
【问题描述】：

我从这个 sql 代码中得到 5 个结果

SELECT count(Location) as total, 
    sum(case when Location= 'Province_A' then 1 else 0 end) AS count_A,
    sum(case when Location= 'Province_A' then 1 else 0 end) AS count_B,
    sum(case when Location= 'Province_A' then 1 else 0 end) AS count_C,
    sum(case when Location= 'Province_A' then 1 else 0 end) AS count_D
FROM dataBase

如何将这 5 个结果捕获到 int 数组中

【问题讨论】：

取决于您与数据库的交互方式，可能使用List<dynamic>？ stackoverflow.com/a/42419101/1188197
您需要的所有信息都在这里：docs.microsoft.com/en-us/dotnet/framework/data/adonet
这是一个具有 1 行和 5 列的单个 结果集。就像任何其他查询一样。您可以使用原始 ADO.NET、Dapper、Entity Framework 或任何其他 ORM 机制

标签： c#

【解决方案1】：

const string queryString = @"
SELECT count(Location) as total, 
    sum(case when Location= 'Province_A' then 1 else 0 end) AS count_A,
    sum(case when Location= 'Province_B' then 1 else 0 end) AS count_B,
    sum(case when Location= 'Province_C' then 1 else 0 end) AS count_C,
    sum(case when Location= 'Province_D' then 1 else 0 end) AS count_D
FROM dataBase";

using (SqlConnection connection = new SqlConnection(connectionString))
{
    connection.Open();
    SqlCommand command = new SqlCommand(queryString, connection);
    using(SqlDataReader reader = command.ExecuteReader())
    {
        reader.Read();
        return new int[] {
            (int)reader["total"],
            (int)reader["count_A"],
            (int)reader["count_B"],
            (int)reader["count_C"],
            (int)reader["count_D"]
        };
    }
}

【讨论】：