如何在wpf中使用数据库查询得到的数值

Question

string con = "Server=.;Database=project;user id=sa;pwd=12345";
string sql1 = "select ttimes from times where tday='2018-1-1'";
SqlConnection mycon = new SqlConnection(con);
mycon.Open();
SqlCommand sqlman = new SqlCommand(sql1, mycon);
string str1 = sql1;
int num1 = Convert.ToInt32(str1);
Console.WriteLine(num1);
这里的sql1的查询数值如何转换为整形num1

Answer 1

你需要调用sqlman的ExecuteScalar()方法，示例如下：

static public int AddProductCategory(string newName, string connString)
{
    Int32 newProdID = 0;
    string sql =
        "INSERT INTO Production.ProductCategory (Name) VALUES (@Name); "
        + "SELECT CAST(scope_identity() AS int)";
    using (SqlConnection conn = new SqlConnection(connString))
    {
        SqlCommand cmd = new SqlCommand(sql, conn);
        cmd.Parameters.Add("@Name", SqlDbType.VarChar);
        cmd.Parameters["@name"].Value = newName;
        try
        {
            conn.Open();
            newProdID = (Int32)cmd.ExecuteScalar();
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.Message);
        }
    }
    return (int)newProdID;
}

更多C# + ADO.NET操作数据库的示例请参考：

C#+ADO.NET数据库入门教程 | 码友网 https://codedefault.com/course/subject/csharp-adonet-mssql-server-example