Question

我无法执行标量查询。＆＃34; =＆＃34;＆＃34; =＆＃34;＆＃34; =＆＃34; ＆＃34 ;.问题是我想从表中访问性别，然后在数据读取器的帮助下更新另一个表。

SqlConnection con1 = new SqlConnection(@"Data Source=(LocalDB)\v11.0;AttachDbFilename=C:\Users\Muneeb\Documents\Visual Studio 2012\Projects\Dwh_Class_Project\Dwh_Class_Project\Centralised_db.mdf;Integrated Security=True");
string gender_get; // get the gender from the database 
SqlCommand cmdgen = new SqlCommand();
cmdgen.CommandText = "select top 1 gender from name_lookupwhere name= 'ahmed'";

con1.Open();       
cmdgen.Connection = con1;
string g = ((string) cmdgen.ExecuteScalar());

MessageBox.Show("test" + g);

Answer 1

您缺少空格：name_lookupwhere应为name_lookup where。

~~另外，请注意您正在执行返回行的select top 1 ...，但使用ExecuteScalar运行查询，该查询需要返回单个值。~~

Answer 2

查询中缺少空格。尝试：

cmdgen.CommandText = "select top 1 gender from name_lookup where name = 'ahmed'";

Answer 3

应该这样做：

    using(SqlConnection con1= new SqlConnection(@"Data Source=(LocalDB)\v11.0;AttachDbFilename=C:\Users\Muneeb\Documents\Visual Studio 2012\Projects\Dwh_Class_Project\Dwh_Class_Project\Centralised_db.mdf;Integrated Security=True"))
    {
        using(SqlCommand cmdgen = new SqlCommand("select top 1 gender from name_lookup where name= @name", con1))
         {
             cmdgen.AddWithValue("@name", "ahmed");

             string g = ((string) cmdgen.ExecuteScalar());

             MessageBox.Show("test" + g);
         }
    }

执行标量查询错误c＃

3 个答案: