我正在从SqlDataReader生成一个csv文件,但是它没有写出列名,我怎么能让它们写出来呢?我正在使用的代码如下:
SqlConnection conn = new SqlConnection(myconn);
SqlCommand cmd = new SqlCommand("dbo.test", conn);
cmd.CommandType = CommandType.StoredProcedure;
conn.Open();
SqlDataReader reader = cmd.ExecuteReader();
StringBuilder sb = new StringBuilder();
StreamWriter sw = new StreamWriter(myfilePath + "testfile.csv");
while (reader.Read())
{
for (int i = 0; i < reader.FieldCount; i++)
{
string value = reader[i].ToString();
if (value.Contains(","))
value = "\"" + value + "\"";
sb.Append(value.Replace(Environment.NewLine, " ") + ",");
}
sb.Length--; // Remove the last comma
sb.AppendLine();
}
conn.Close();
sw.Write(sb.ToString());
sw.Close();
答案 0 :(得分:9)
读取所有列名称并将其附加到sb
然后迭代读者。
SqlDataReader reader = cmd.ExecuteReader();
StringBuilder sb = new StringBuilder();
//Get All column
var columnNames = Enumerable.Range(0, reader.FieldCount)
.Select(reader.GetName) //OR .Select("\""+ reader.GetName"\"")
.ToList();
//Create headers
sb.Append(string.Join(",", columnNames));
//Append Line
sb.AppendLine();
while (reader.Read())
....
答案 1 :(得分:2)
使用此solution我创建了一个扩展名。
/// <summary>
///
/// </summary>
/// <param name="reader"></param>
/// <param name="filename"></param>
/// <param name="path">if null/empty will use IO.Path.GetTempPath()</param>
/// <param name="extension">will use csv by default</param>
public static void ToCsv(this IDataReader reader, string filename, string path = null, string extension = "csv")
{
int nextResult = 0;
do
{
var filePath = Path.Combine(string.IsNullOrEmpty(path) ? Path.GetTempPath() : path, string.Format("{0}.{1}", filename, extension));
using (StreamWriter writer = new StreamWriter(filePath))
{
writer.WriteLine(string.Join(",", Enumerable.Range(0, reader.FieldCount).Select(reader.GetName).ToList()));
int count = 0;
while (reader.Read())
{
writer.WriteLine(string.Join(",", Enumerable.Range(0, reader.FieldCount).Select(reader.GetValue).ToList()));
if (++count % 100 == 0)
{
writer.Flush();
}
}
}
filename = string.Format("{0}-{1}", filename, ++nextResult);
}
while (reader.NextResult());
}
答案 2 :(得分:1)
您可以使用SqlDataReader.GetName获取列名称
for (int i = 0; i < reader.FieldCount; i++)
{
string columnName = reader.GetName(i);
}
您还可以创建如下所示的扩展方法:
public static List<string> ToCSV(this IDataReader dataReader, bool includeHeaderAsFirstRow, string separator)
{
List<string> csvRows = new List<string>();
StringBuilder sb = null;
if (includeHeaderAsFirstRow)
{
sb = new StringBuilder();
for (int index = 0; index < dataReader.FieldCount; index++)
{
if (dataReader.GetName(index) != null)
sb.Append(dataReader.GetName(index));
if (index < dataReader.FieldCount - 1)
sb.Append(separator);
}
csvRows.Add(sb.ToString());
}
while (dataReader.Read())
{
sb = new StringBuilder();
for (int index = 0; index < dataReader.FieldCount - 1; index++)
{
if (!dataReader.IsDBNull(index))
{
string value = dataReader.GetValue(index).ToString();
if (dataReader.GetFieldType(index) == typeof(String))
{
//If double quotes are used in value, ensure each are replaced but 2.
if (value.IndexOf("\"") >= 0)
value = value.Replace("\"", "\"\"");
//If separtor are is in value, ensure it is put in double quotes.
if (value.IndexOf(separator) >= 0)
value = "\"" + value + "\"";
}
sb.Append(value);
}
if (index < dataReader.FieldCount - 1)
sb.Append(separator);
}
if (!dataReader.IsDBNull(dataReader.FieldCount - 1))
sb.Append(dataReader.GetValue(dataReader.FieldCount - 1).ToString().Replace(separator, " "));
csvRows.Add(sb.ToString());
}
dataReader.Close();
sb = null;
return csvRows;
}
示例:强>
List<string> rows = null;
using (SqlDataReader dataReader = command.ExecuteReader())
{
rows = dataReader.ToCSV(includeHeadersAsFirstRow, separator);
dataReader.Close();
}
答案 3 :(得分:1)
我开发了以下高性能扩展程序
static void Main(string[] args)
{
SqlConnection sqlCon = new SqlConnection("Removed");
sqlCon.Open();
SqlCommand sqlCmd = new SqlCommand("Select * from Table", sqlCon);
SqlDataReader reader = sqlCmd.ExecuteReader();
string csv=reader.ToCSVHighPerformance(true);
File.WriteAllText("Test.CSV", csv);
reader.Close();
sqlCon.Close();
}
<强> Extention:强>
public static string ToCSVHighPerformance(this IDataReader dataReader, bool includeHeaderAsFirstRow = true,
string separator = ",")
{
DataTable dataTable = new DataTable();
StringBuilder csvRows = new StringBuilder();
string row = "";
int columns ;
try
{
dataTable.Load(dataReader);
columns= dataTable.Columns.Count;
//Create Header
if (includeHeaderAsFirstRow)
{
for (int index = 0; index < columns; index++)
{
row += (dataTable.Columns[index]);
if (index < columns - 1)
row += (separator);
}
row += (Environment.NewLine);
}
csvRows.Append(row);
//Create Rows
for (int rowIndex = 0; rowIndex < dataTable.Rows.Count; rowIndex++)
{
row = "";
//Row
for (int index = 0; index < columns - 1; index++)
{
string value = dataTable.Rows[rowIndex][index].ToString();
//If type of field is string
if (dataTable.Rows[rowIndex][index] is string)
{
//If double quotes are used in value, ensure each are replaced by double quotes.
if (value.IndexOf("\"") >= 0)
value = value.Replace("\"", "\"\"");
//If separtor are is in value, ensure it is put in double quotes.
if (value.IndexOf(separator) >= 0)
value = "\"" + value + "\"";
//If string contain new line character
while (value.Contains("\r"))
{
value = value.Replace("\r", "");
}
while (value.Contains("\n"))
{
value = value.Replace("\n", "");
}
}
row += value;
if (index < columns - 1)
row += separator;
}
dataTable.Rows[rowIndex][columns - 1].ToString().ToString().Replace(separator, " ");
row += Environment.NewLine;
csvRows.Append(row);
}
}
catch (Exception ex)
{
throw ex;
}
return csvRows.ToString();
}
答案 4 :(得分:0)
您可以使用SqlDataReader.GetName
方法获取列的名称,如下所示:
for(int i = 0; i < reader.FieldCount; i++)
{
string columnName = reader.GetName(i);
}