c# - Can you get the column names from a SqlDataReader?

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Top 5 Answer for c# - Can you get the column names from a SqlDataReader?

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var reader = cmd.ExecuteReader();  var columns = new List<string>();  for(int i=0;i<reader.FieldCount;i++) {    columns.Add(reader.GetName(i)); } 


var columns = Enumerable.Range(0, reader.FieldCount).Select(reader.GetName).ToList(); 
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There is a GetName function on the SqlDataReader which accepts the column index and returns the name of the column.

Conversely, there is a GetOrdinal which takes in a column name and returns the column index.

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You can get the column names from a DataReader.

Here is the important part:

  for (int col = 0; col < SqlReader.FieldCount; col++)   {     Console.Write(SqlReader.GetName(col).ToString());         // Gets the column name     Console.Write(SqlReader.GetFieldType(col).ToString());    // Gets the column type     Console.Write(SqlReader.GetDataTypeName(col).ToString()); // Gets the column database type   } 
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Already mentioned. Just a LINQ answer:

var columns = reader.GetSchemaTable().Rows                                      .Cast<DataRow>()                                      .Select(r => (string)r["ColumnName"])                                      .ToList();  //Or  var columns = Enumerable.Range(0, reader.FieldCount)                         .Select(reader.GetName)                         .ToList(); 

The second one is cleaner and much faster. Even if you cache GetSchemaTable in the first approach, the querying is going to be very slow.

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If you want the column names only, you can do:

List<string> columns = new List<string>(); using (SqlDataReader reader = cmd.ExecuteReader(CommandBehavior.SchemaOnly)) {     DataTable dt = reader.GetSchemaTable();     foreach (DataRow row in dt.Rows)     {         columns.Add(row.Field<String>("ColumnName"));     } } 

But if you only need one row, I like my AdoHelper addition. This addition is great if you have a single line query and you don't want to deal with data table in you code. It's returning a case insensitive dictionary of column names and values.

public static Dictionary<string, string> ExecuteCaseInsensitiveDictionary(string query, string connectionString, Dictionary<string, string> queryParams = null) {     Dictionary<string, string> CaseInsensitiveDictionary = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);     try     {         using (SqlConnection conn = new SqlConnection(connectionString))         {             conn.Open();             using (SqlCommand cmd = new SqlCommand())             {                 cmd.Connection = conn;                 cmd.CommandType = CommandType.Text;                 cmd.CommandText = query;                  // Add the parameters for the SelectCommand.                 if (queryParams != null)                     foreach (var param in queryParams)                         cmd.Parameters.AddWithValue(param.Key, param.Value);                  using (SqlDataReader reader = cmd.ExecuteReader())                 {                     DataTable dt = new DataTable();                     dt.Load(reader);                     foreach (DataRow row in dt.Rows)                     {                         foreach (DataColumn column in dt.Columns)                         {                             CaseInsensitiveDictionary.Add(column.ColumnName, row[column].ToString());                         }                     }                 }             }             conn.Close();         }     }     catch (Exception ex)     {         throw ex;     }     return CaseInsensitiveDictionary; } 

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