在编写有关数据库方面的C#程序时，经常需要知道数据库的表中各字段的以下信息：
1. 用于OracleParameter(或SqlParameter,...)中的字段和属性的数据库特定的数据类型。
2. 其对应的.NET数据类型。
如下面的程序片断所示：
using (OracleConnection conn = new OracleConnection(Pub.ConnString))
{
conn.Open(); OracleCommand comm = new OracleCommand( "SELECT trdate,txcode,drcrf,amount,balance,tellerno,txnote,zoneno,nodeno FROM detail "+ "WHERE accno=:accno AND currtype=:currtype ORDER BY accno,currtype,trdate,seqno", conn); comm.Parameters.Add("accno", OracleDbType.Int64).Value = long.Parse(acc.Substring(4,13)); comm.Parameters.Add("currtype", OracleDbType.Int16).Value = curr; using (OracleDataReader r = comm.ExecuteReader())
{
for (cnt = 0; r.Read(); cnt++) { DataRow dr = dt.NewRow(); dr["TrDate"] = r.GetDateTime(0); dr["Txcode"] = r.GetInt32(1); dr["Drcrf"] = IcbcEtc.GetDrcrfString(r.GetInt16(2)); dr["Amount"] = r.GetInt64(3) / R; dr["Balance"] = r.GetInt64(4) / R; dr["Tellerno"] = r.GetInt32(5); dr["TxNote"] = r.GetString(6); dr["Zoneno"] = r.GetInt32(7); dr["Nodeno"] = r.GetInt32(8); dr["Txname"] = DbTrxCode.GetNewName((int)dr["Txcode"]); dt.Rows.Add(dr);
} }
} 为此，我编写了一个小工具，其应用示例如下： 
这里是源程序(ODP.NET版)，需要下载“Oracle Data Provider for .NET”，其命名空间是: Oracle.DataAccess.Client。
using System;using System.Data;using System.Text;using System.Windows.Forms;using System.Drawing;using Oracle.DataAccess.Client;namespace Skyiv.Util.Odpnet{ class OdpnetDlg : Form { Label lblTable; TextBox tbxConn; TextBox tbxSql; TextBox tbxMsg; Button btnSubmit; CheckBox chkStru; DataGrid dgOut; string strConn = "Data Source=ora-m38;User ID=test;Password=p@ssw0rd"; public OdpnetDlg() { SuspendLayout(); btnSubmit = new Button(); btnSubmit.Text = "执行"; btnSubmit.Location = new Point(10, 420); btnSubmit.Size = new Size(60, 24); btnSubmit.Click += new EventHandler(Submit_Click); btnSubmit.Anchor = (AnchorStyles.Bottom | AnchorStyles.Left); chkStru = new CheckBox(); chkStru.Text = "结构"; chkStru.Location = new Point(80, 420); chkStru.Size = new Size(60, 24); chkStru.Anchor = (AnchorStyles.Bottom | AnchorStyles.Left); lblTable = new Label(); lblTable.Text = "数据源"; lblTable.Location = new Point(12, 460); lblTable.Size = new Size(70, 24); lblTable.Anchor = (AnchorStyles.Bottom | AnchorStyles.Left); tbxConn = new TextBox(); tbxConn.Text = strConn; tbxConn.Location = new Point(83, 456); tbxConn.Size = new Size(626, 20); tbxConn.Anchor = (AnchorStyles.Bottom | AnchorStyles.Left | AnchorStyles.Right); tbxSql = new TextBox(); tbxSql.Text = "select *\r\nfrom v$version\r\n"; tbxSql.Location = new Point(10, 10); tbxSql.Size = new Size(240, 200); tbxSql.Multiline = true; tbxSql.ScrollBars = ScrollBars.Both; tbxSql.AcceptsReturn = true; tbxSql.WordWrap = true; tbxSql.Anchor = (AnchorStyles.Top | AnchorStyles.Left); tbxMsg = new TextBox(); tbxMsg.Location = new Point(10, 220); tbxMsg.Size = new Size(240, 190); tbxMsg.Multiline = true; tbxMsg.ScrollBars = ScrollBars.Both; tbxMsg.AcceptsReturn = true; tbxMsg.WordWrap = true; tbxMsg.Anchor = (AnchorStyles.Top | AnchorStyles.Bottom | AnchorStyles.Left); dgOut = new DataGrid(); dgOut.Location = new Point(260, 10); dgOut.Size = new Size(450, 436); dgOut.CaptionVisible = false; dgOut.ReadOnly = true; dgOut.Anchor = (AnchorStyles.Top | AnchorStyles.Bottom | AnchorStyles.Left | AnchorStyles.Right); Controls.AddRange(new Control[]{btnSubmit, chkStru, lblTable, tbxSql, tbxMsg, tbxConn, dgOut}); Text = "数据库查询(ODPNET)"; ClientSize = new Size(720, 490); WindowState = FormWindowState.Maximized; ResumeLayout(false); } void DisplayError(Exception ex) { StringBuilder sb = new StringBuilder(); while (ex != null) { sb.Append("> "); sb.Append(ex.GetType()); sb.Append(Environment.NewLine); OracleException e = ex as OracleException; if (e != null) { for (int i = 0; i < e.Errors.Count; i++) sb.AppendFormat( "Index: {1}{0}Message: {2}{0}DataSource: {3}{0}Source: {4}{0}Number: {5}{0}Procedure: {6}{0}", Environment.NewLine, i, e.Errors[i].Message, e.Errors[i].DataSource, e.Errors[i].Source, e.Errors[i].Number, e.Errors[i].Procedure ); } else sb.Append(ex.Message); sb.Append(Environment.NewLine); ex = ex.InnerException; } tbxMsg.Text = sb.ToString(); } void Submit_Click(object sender, EventArgs e) { btnSubmit.Enabled = false; string sql = tbxSql.Text.Trim(); if (sql.Length == 0) return; try { int rows = -2; string strType = "查询"; using (OracleConnection conn = new OracleConnection(tbxConn.Text)) { conn.Open(); OracleCommand comm = new OracleCommand(sql, conn); if (!isQuery(sql)) { strType = "非查询"; rows = comm.ExecuteNonQuery(); } else if (chkStru.Checked) { strType = "表结构"; dgOut.DataSource = RunQueryTableStruct(comm); } else dgOut.DataSource = RunQueryTableData(comm); } tbxMsg.Text = "运行 SQL 语句完毕(" + strType + ")"; if (rows >= 0) tbxMsg.Text = "受影响的行数: " + rows.ToString("N0"); } catch (Exception ex) { DisplayError(ex); } btnSubmit.Enabled = true; } bool isQuery(string sql) { return sql.Substring(0, 6).ToUpper() == "SELECT"; } private DataView RunQueryTableData(OracleCommand comm) { OracleDataAdapter da = new OracleDataAdapter(); da.SelectCommand = comm; DataSet ds = new DataSet(); da.Fill(ds); return ds.Tables[0].DefaultView; } private DataView RunQueryTableStruct(OracleCommand comm) { DataTable dt = new DataTable(); dt.Columns.Add("#", typeof(int)); dt.Columns.Add("字段名", typeof(string)); dt.Columns.Add("数据类型", typeof(string)); dt.Columns.Add("源数据类型", typeof(string)); dt.Columns.Add("大小", typeof(string)); dt.Columns.Add("备注", typeof(string)); using (OracleDataReader r = comm.ExecuteReader(CommandBehavior.KeyInfo)) { DataTable dt0 = r.GetSchemaTable(); //return dt0.DefaultView; foreach (DataRow dr0 in dt0.Rows) { DataRow dr = dt.NewRow(); dr[0] = (int)dr0["ColumnOrdinal"]; dr[1] = (string)dr0["ColumnName"]; dr[2] = GetBriefType(dr0["DataType"]); dr[3] = ((OracleDbType)dr0["ProviderType"]).ToString(); dr[4] = string.Format( "({0},{1}) {2}", GetInt16(dr0["NumericPrecision"]), GetInt16(dr0["NumericScale"]), (int)dr0["ColumnSize"] ); dr[5] = string.Format( "{0}{1}{2}{3}{4}{5}{6}{7}{8}{9}", isTrue(dr0["AllowDBNull" ]) ? "AllowDBNull " : "", isTrue(dr0["IsKey" ]) ? "Key " : "", isTrue(dr0["IsUnique" ]) ? "Unique " : "", isTrue(dr0["IsLong" ]) ? "Long " : "", isTrue(dr0["IsReadOnly" ]) ? "ReadOnly " : "", isTrue(dr0["IsRowID" ]) ? "RowID " : "", isTrue(dr0["IsAliased" ]) ? "Aliased " : "", isTrue(dr0["IsByteSemantic"]) ? "ByteSemantic " : "", isTrue(dr0["IsExpression" ]) ? "Expression " : "", isTrue(dr0["IsHidden" ]) ? "Hidden" : "" ); dt.Rows.Add(dr); } } return dt.DefaultView; } bool isTrue(object obj) { if (obj == DBNull.Value) return false; return (bool)obj; } short GetInt16(object obj) { if (obj == DBNull.Value) return -1; else return (short)obj; } string GetBriefType(object obj) { string s = (obj as Type).ToString(); if (string.CompareOrdinal(s, 0, "System.", 0, 7) == 0) s = s.Substring(7); return s; } static void Main() { Application.Run(new OdpnetDlg()); } }} 此外，该程序还有以下各种版本：
System.Data.OracleClient;
System.Data.SqlClient;
System.Data.OleDb;
System.Data.Odbc;
限于篇幅，这里不就贴出源程序了，各位可以自己在ODP.NET版本的基础上稍做修改就行了。
同样是Oracle数据库，使用Oracle.DataAccess.Client和System.Data.OracleClient还是有区别的，请参阅:
“Comparing the Microsoft .NET Framework 1.1 Data Provider for Oracle and the Oracle Data Provider for .NET ”
例如，对于数据库中的NUMBER类型，Oracle.DataAccess.Client对应的.NET类型可以是byte、short、int、long、decimal等类型，而System.Data.OracleClient一般都对应为decimal类型。
