当使用C#SELECT COUNT(*) [英] Using select count(*) in c#
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问题描述
字符串dd_webCofig = ConfigurationManager.ConnectionStrings [server132]的ConnectionString。
的SqlConnection ddlistconn =新的SqlConnection(dd_webCofig);
ddlistconn.Open(); 从哪里jud_order = complex_name一个@和case_no = @ b和签署= @ c和jud_order_date = @ D和user_code = @ E选择COUNT(*)
串ddlist =;
的SqlCommand ddlistCmd =新的SqlCommand(ddlist,ddlistconn);
ddlistCmd.Parameters.AddWithValue(一,一个);
ddlistCmd.Parameters.AddWithValue(B,一个);
ddlistCmd.Parameters.AddWithValue(C,一个);
ddlistCmd.Parameters.AddWithValue(D,一个);
ddlistCmd.Parameters.AddWithValue(E,一个);
SqlDataReader的myReader = ddlistCmd.ExecuteReader();
我有它返回的行数,我现在的问题为t如何读取输出上面的查询查询的?
我想是
如果(计数= 0)
{
//待办事项
}
,否则如果(counnt大于0)
{
//做别的事情
}
解决方案
您想要使用的 的ExecuteScalar();
,而不是将返回一个结果。
所以这行:
ddlistCmd.ExecuteReader();
应该是:
ddlistCmd.ExecuteScalar();
然后你就可以分配到计数
之后类型转换的结果。
String dd_webCofig = ConfigurationManager.ConnectionStrings["server132"].ConnectionString;
SqlConnection ddlistconn = new SqlConnection(dd_webCofig);
ddlistconn.Open();
string ddlist = "select count(*) from jud_order where complex_name=@a and case_no=@b and sign=@c and jud_order_date=@d and user_code=@e";
SqlCommand ddlistCmd = new SqlCommand(ddlist, ddlistconn);
ddlistCmd.Parameters.AddWithValue("a", "a");
ddlistCmd.Parameters.AddWithValue("b", "a");
ddlistCmd.Parameters.AddWithValue("c", "a");
ddlistCmd.Parameters.AddWithValue("d", "a");
ddlistCmd.Parameters.AddWithValue("e", "a");
SqlDataReader myReader = ddlistCmd.ExecuteReader();
I am having the above query which returns number of rows, now my problem is how t read the output of the query? What i want is
if(count=0)
{
//Do
}
else if(counnt >0)
{
//Do something else
}
解决方案
You want to use ExecuteScalar();
instead which will return a single result.
So this line:
ddlistCmd.ExecuteReader();
should be:
ddlistCmd.ExecuteScalar();
which you can then assign to count
after type casting the result.
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