使用Dapper.NET在一次往返中使用多个SQL语句

Question

ADO.NET中有一个很好的功能,允许您在一次往返中将多个SQL语句发送到数据库,并接收所有语句的结果:

var command = new SqlCommand("SELECT count(*) FROM TableA; SELECT count(*) FROM TableB;", connection);

using(var reader = command.ExecuteReader())
{
    reader.Read();
    resultA = reader.GetInt32(0);
    reader.NextResult();
    reader.Read();
    resultB = reader.GetInt32(0);
}

Dapper.NET中是否有类似的功能？

Answer 1

是的,Dapper QueryMultiple扩展可以做到这一点:

string query = @"SELECT COUNT(*) FROM TABLEA;
                 SELECT COUNT(*) FROM TABLEB";
using (var multi = connection.QueryMultiple(query, null))
{
    int countA = multi.Read<int>().Single();
    int countB = multi.Read<int>().Single();
}     

根据Marc Gravell的说法,这是在一个批处理中执行多个查询的理想方式.

注意:Dapper创建者Sam Saffron在使用代码示例时发布了详细解释QueryMultiple.

Answer 2

var grid = connection.QueryMultiple("
             SELECT COUNT(*) FROM TABLEA
             SELECT COUNT(*) FROM TABLEB
             SELECT COUNT(*) FROM TABLEC");
var lstResult = new List<int>();
var isNext = false;
do{
    var first2 = info.Read<int>().Single();
    lstResult.Add(first2);
    isNext=info.IsConsumed;
}
while (!isNext);