C# 组合查询并使用1个datareader
我想从datareader接收两个值。但我不知道如何把它放到一个查询中。我如何仅使用一个sqldatareader来接收它C# 组合查询并使用1个datareader,c#,sql,ado.net,C#,Sql,Ado.net,我想从datareader接收两个值。但我不知道如何把它放到一个查询中。我如何仅使用一个sqldatareader来接收它 string query = "select date from ars.kmstand where ritnr=(select max(ritnr) from ars.kmstand)"; string query2 = "select nr from ars.kmstand where ritnr=(select max(ritnr) from ars
string query = "select date from ars.kmstand where ritnr=(select max(ritnr) from ars.kmstand)";
string query2 = "select nr from ars.kmstand where ritnr=(select max(ritnr) from ars.kmstand)";
SqlCommand com = new SqlCommand(query2, conn);
SqlDataReader rt = com.ExecuteReader();
while (rt.Read())
{
ritnr = rt.GetInt32(0);
}
rt.Close();
SqlCommand comm = new SqlCommand(query, conn);
SqlDataReader rd = comm.ExecuteReader();
while (rd.Read())
{
value = rd.GetSqlDateTime(0);
}
DbDataReader
上的方法及其派生类型(包括SqldataReader
)将从一个数据集移动到下一个数据集
因此:
// ...
var rdr = cmd.ExecuteReader();
while (rdr.Read()) {
// Read rows from the first dataset
}
if (rdr.NextResult()) {
// There is a second dataset
while (rdr.Read()) {
// ...
}
}
在命令中,只需执行多个操作,每个操作返回行(这可能在您执行的存储过程中)。组合查询并将列索引传递给IDataReader的GetXXX方法,从结果集中获取每列的值
string query = "select nhr, date from ars.kmstand where ritnr=(select max(ritnr) from ars.kmstand)";
SqlCommand com = new SqlCommand(query, conn);
SqlDataReader rt = com.ExecuteReader();
while (rt.Read()) {
int nhr = rt.GetInt32(0);
SqlDateTime date = rt.GetSqlDateTime(1);
}
rt.Close();
谢谢,更短更好。真的很有帮助!