如何使用executescalar（）将选择查询结果（一个结果）存储到变量中？ （ASP.NET）

Question

我必须将选择查询结果存储在变量中。我在asp.net中是新的。我用了executescalar，但是没有用。我尝试了很多次，但是我在这里失败了，我最后一次尝试：

using (SqlConnection sqlConnection = new SqlConnection())
{
    var connetionString = ConfigurationManager.ConnectionStrings["connections"].ToString();
    sqlConnection.ConnectionString = connetionString;
    string sql = "Select sum((prime_comptant+10)*0.12) from mvt_garantie_quittance where numero_quittance='" + numQuittance + "'";
    SqlDataAdapter adapter = new SqlDataAdapter(sql, sqlConnection);
    DataSet dataset = new DataSet();
    adapter.Fill(dataset);
    string result = dataset.Tables[0].ToString();
}

您可以将代码修复给我吗？我必须将结果存储在变量中

Answer 1

string sql = "Select sum((prime_comptant+10)*0.12) from mvt_garantie_quittance where numero_quittance='" + numQuittance + "'";

var connetionString = ConfigurationManager.ConnectionStrings["connections"].ToString();

string result = null;

using (SqlConnection conn = new SqlConnection(connetionString))
{
    SqlCommand cmd = new SqlCommand(sql, conn);
    conn.Open();
    result = cmd.ExecuteScalar().ToString();
}