C# Select Transact-SQL（Table 列属性）

Question

我想使用 c# select Table 列属性。我写了这段代码。我的查询在 sqlserver 上运行。但是我在 C# 中没有得到最大长度。

我的查询在这里

//TableName:Contents, ColumnName : Title
select Col_Length('Contents','Title') as columnLengthh

结果在这里：

我的 C# 代码在这里：

string columnLength = "select Col_Length('Contents','Title') as columnLengthh";
                    adapter = new SqlDataAdapter(columnLength, connection);
                    dataSet = new DataSet();
                    adapter.Fill(dataSet);
                    DataTable dataTable2 = dataSet.Tables[0];
                    foreach (DataRow row in dataTable2.Rows)
                    {
                        var x  = row["columnLengthh"].ToString();
                    }

结果 (x = -1)

我如何在 C# 中获取长度。

请帮忙！

Answer 1

只需使用 SqlConnection、SqlCommand、SqlReader 等类与 SQL 服务器通信。

string queryString = "select Col_Length('Contents','Title') as columnLengthh";
string connectionString = "Your connection string";
SqlConnection connection = null;
try
{
    connection = new SqlConnection(connectionString)
    using (SqlCommand command = new SqlCommand(queryString, connection)) ;
    {
        connection.Open();
        var result = command.ExecuteScalar();
        Console.WriteLine("columnLengthh = {0}", result);
    }
}
finally
{
    connection.Close();
}

Answer 2

检查您的查询是否正确

更改 connectionString 以匹配您的内容 - 例如：

   string connectionString = @"server=localhost\mysqlserver;database=master;Trusted_Connection=True;";

并使用以下代码：

        string queryString = "select Col_Length('Contents','Title') as columnLengthh";
        string connectionString = @"your con string";
        SqlConnection connection = null;
        try
        {
            connection = new SqlConnection(connectionString);

            using (SqlCommand command = new SqlCommand(queryString, connection))
            {
                connection.Open();
                var result = command.ExecuteScalar();
                Console.WriteLine("columnLengthh = {0}", result);
            }
        }
        catch (Exception ex)
        {
            ex.ToString();
        }
        finally
        {
            connection.Close();
        }

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