本文实例讲述了C#基于SQLiteHelper类似SqlHelper类实现存取Sqlite数据库的方法。分享给大家供大家参考。具体如下：
这个类不是我实现的，英文原文地址为http://www.eggheadcafe.com/articles/20050315.asp，这里修改了原文中分析sql语句参数的方法，将方法名修改为AttachParameters，将其修饰符修改为private，并直接传递command到这个方法，直接绑定参数到comand。修改后的代码如下
using System; using System.Data; using System.Text.RegularExpressions; using System.Xml; using System.IO; using System.Collections; using System.Data.SQLite; namespace DBUtility.SQLite { /// <summary> /// SQLiteHelper is a utility class similar to "SQLHelper" in MS /// Data Access Application Block and follows similar pattern. /// </summary> public class SQLiteHelper { /// <summary> /// Creates a new <see cref="SQLiteHelper"/> instance. The ctor is marked private since all members are static. /// </summary> private SQLiteHelper() { } /// <summary> /// Creates the command. /// </summary> /// <param name="connection">Connection.</param> /// <param name="commandText">Command text.</param> /// <param name="commandParameters">Command parameters.</param> /// <returns>SQLite Command</returns> public static SQLiteCommand CreateCommand(SQLiteConnection connection, string commandText, params SQLiteParameter[] commandParameters) { SQLiteCommand cmd = new SQLiteCommand(commandText, connection); if (commandParameters.Length > 0) { foreach (SQLiteParameter parm in commandParameters) cmd.Parameters.Add(parm); } return cmd; } /// <summary> /// Creates the command. /// </summary> /// <param name="connectionString">Connection string.</param> /// <param name="commandText">Command text.</param> /// <param name="commandParameters">Command parameters.</param> /// <returns>SQLite Command</returns> public static SQLiteCommand CreateCommand(string connectionString, string commandText, params SQLiteParameter[] commandParameters) { SQLiteConnection cn = new SQLiteConnection(connectionString); SQLiteCommand cmd = new SQLiteCommand(commandText, cn); if (commandParameters.Length > 0) { foreach (SQLiteParameter parm in commandParameters) cmd.Parameters.Add(parm); } return cmd; } /// <summary> /// Creates the parameter. /// </summary> /// <param name="parameterName">Name of the parameter.</param> /// <param name="parameterType">Parameter type.</param> /// <param name="parameterValue">Parameter value.</param> /// <returns>SQLiteParameter</returns> public static SQLiteParameter CreateParameter(string parameterName, System.Data.DbType parameterType, object parameterValue) { SQLiteParameter parameter = new SQLiteParameter(); parameter.DbType = parameterType; parameter.ParameterName = parameterName; parameter.Value = parameterValue; return parameter; } /// <summary> /// Shortcut method to execute dataset from SQL Statement and object[] arrray of parameter values /// </summary> /// <param name="connectionString">SQLite Connection string</param> /// <param name="commandText">SQL Statement with embedded "@param" style parameter names</param> /// <param name="paramList">object[] array of parameter values</param> /// <returns></returns> public static DataSet ExecuteDataSet(string connectionString, string commandText, object[] paramList) { SQLiteConnection cn = new SQLiteConnection(connectionString); SQLiteCommand cmd = cn.CreateCommand(); cmd.CommandText = commandText; if (paramList != null) { AttachParameters(cmd,commandText, paramList); } DataSet ds = new DataSet(); if (cn.State == ConnectionState.Closed) cn.Open(); SQLiteDataAdapter da = new SQLiteDataAdapter(cmd); da.Fill(ds); da.Dispose(); cmd.Dispose(); cn.Close(); return ds; } /// <summary> /// Shortcut method to execute dataset from SQL Statement and object[] arrray of parameter values /// </summary> /// <param name="cn">Connection.</param> /// <param name="commandText">Command text.</param> /// <param name="paramList">Param list.</param> /// <returns></returns> public static DataSet ExecuteDataSet(SQLiteConnection cn, string commandText, object[] paramList) { SQLiteCommand cmd = cn.CreateCommand(); cmd.CommandText = commandText; if (paramList != null) { AttachParameters(cmd,commandText, paramList); } DataSet ds = new DataSet(); if (cn.State == ConnectionState.Closed) cn.Open(); SQLiteDataAdapter da = new SQLiteDataAdapter(cmd); da.Fill(ds); da.Dispose(); cmd.Dispose(); cn.Close(); return ds; } /// <summary> /// Executes the dataset from a populated Command object. /// </summary> /// <param name="cmd">Fully populated SQLiteCommand</param> /// <returns>DataSet</returns> public static DataSet ExecuteDataset(SQLiteCommand cmd) { if (cmd.Connection.State == ConnectionState.Closed) cmd.Connection.Open(); DataSet ds = new DataSet(); SQLiteDataAdapter da = new SQLiteDataAdapter(cmd); da.Fill(ds); da.Dispose(); cmd.Connection.Close(); cmd.Dispose(); return ds; } /// <summary> /// Executes the dataset in a SQLite Transaction /// </summary> /// <param name="transaction">SQLiteTransaction. Transaction consists of Connection, Transaction, /// and Command, all of which must be created prior to making this method call. </param> /// <param name="commandText">Command text.</param> /// <param name="commandParameters">Sqlite Command parameters.</param> /// <returns>DataSet</returns> /// <remarks>user must examine Transaction Object and handle transaction.connection .Close, etc.</remarks> public static DataSet ExecuteDataset(SQLiteTransaction transaction, string commandText, params SQLiteParameter[] commandParameters) { if (transaction == null) throw new ArgumentNullException("transaction"); if (transaction != null && transaction.Connection == null) throw new ArgumentException("The transaction was rolled back or committed, please provide an open transaction.", "transaction"); IDbCommand cmd = transaction.Connection.CreateCommand(); cmd.CommandText = commandText; foreach (SQLiteParameter parm in commandParameters) { cmd.Parameters.Add(parm); } if (transaction.Connection.State == ConnectionState.Closed) transaction.Connection.Open(); DataSet ds = ExecuteDataset((SQLiteCommand)cmd); return ds; } /// <summary> /// Executes the dataset with Transaction and object array of parameter values. /// </summary> /// <param name="transaction">SQLiteTransaction. Transaction consists of Connection, Transaction, /// and Command, all of which must be created prior to making this method call. </param> /// <param name="commandText">Command text.</param> /// <param name="commandParameters">object[] array of parameter values.</param> /// <returns>DataSet</returns> /// <remarks>user must examine Transaction Object and handle transaction.connection .Close, etc.</remarks> public static DataSet ExecuteDataset(SQLiteTransaction transaction, string commandText, object[] commandParameters) { if (transaction == null) throw new ArgumentNullException("transaction"); if (transaction != null && transaction.Connection == null) throw new ArgumentException("The transaction was rolled back or committed, please provide an open transaction.", "transaction"); IDbCommand cmd = transaction.Connection.CreateCommand(); cmd.CommandText = commandText; AttachParameters((SQLiteCommand)cmd,cmd.CommandText, commandParameters); if (transaction.Connection.State == ConnectionState.Closed) transaction.Connection.Open(); DataSet ds = ExecuteDataset((SQLiteCommand)cmd); return ds; } #region UpdateDataset /// <summary> /// Executes the respective command for each inserted, updated, or deleted row in the DataSet. /// </summary> /// <remarks> /// e.g.: /// UpdateDataset(conn, insertCommand, deleteCommand, updateCommand, dataSet, "Order"); /// </remarks> /// <param name="insertCommand">A valid SQL statement to insert new records into the data source</param> /// <param name="deleteCommand">A valid SQL statement to delete records from the data source</param> /// <param name="updateCommand">A valid SQL statement used to update records in the data source</param> /// <param name="dataSet">The DataSet used to update the data source</param> /// <param name="tableName">The DataTable used to update the data source.</param> public static void UpdateDataset(SQLiteCommand insertCommand, SQLiteCommand deleteCommand, SQLiteCommand updateCommand, DataSet dataSet, string tableName) { if (insertCommand == null) throw new ArgumentNullException("insertCommand"); if (deleteCommand == null) throw new ArgumentNullException("deleteCommand"); if (updateCommand == null) throw new ArgumentNullException("updateCommand"); if (tableName == null || tableName.Length == 0) throw new ArgumentNullException("tableName"); // Create a SQLiteDataAdapter, and dispose of it after we are done using (SQLiteDataAdapter dataAdapter = new SQLiteDataAdapter()) { // Set the data adapter commands dataAdapter.UpdateCommand = updateCommand; dataAdapter.InsertCommand = insertCommand; dataAdapter.DeleteCommand = deleteCommand; // Update the dataset changes in the data source dataAdapter.Update(dataSet, tableName); // Commit all the changes made to the DataSet dataSet.AcceptChanges(); } } #endregion /// <summary> /// ShortCut method to return IDataReader /// NOTE: You should explicitly close the Command.connection you passed in as /// well as call Dispose on the Command after reader is closed. /// We do this because IDataReader has no underlying Connection Property. /// </summary> /// <param name="cmd">SQLiteCommand Object</param> /// <param name="commandText">SQL Statement with optional embedded "@param" style parameters</param> /// <param name="paramList">object[] array of parameter values</param> /// <returns>IDataReader</returns> public static IDataReader ExecuteReader(SQLiteCommand cmd, string commandText, object[] paramList) { if (cmd.Connection == null) throw new ArgumentException("Command must have live connection attached.", "cmd"); cmd.CommandText = commandText; AttachParameters(cmd,commandText, paramList); if (cmd.Connection.State == ConnectionState.Closed) cmd.Connection.Open(); IDataReader rdr = cmd.ExecuteReader(CommandBehavior.CloseConnection); return rdr; } /// <summary> /// Shortcut to ExecuteNonQuery with SqlStatement and object[] param values /// </summary> /// <param name="connectionString">SQLite Connection String</param> /// <param name="commandText">Sql Statement with embedded "@param" style parameters</param> /// <param name="paramList">object[] array of parameter values</param> /// <returns></returns> public static int ExecuteNonQuery(string connectionString, string commandText, params object[] paramList) { SQLiteConnection cn = new SQLiteConnection(connectionString); SQLiteCommand cmd = cn.CreateCommand(); cmd.CommandText = commandText; AttachParameters(cmd,commandText, paramList); if (cn.State == ConnectionState.Closed) cn.Open(); int result = cmd.ExecuteNonQuery(); cmd.Dispose(); cn.Close(); return result; } public static int ExecuteNonQuery(SQLiteConnection cn, string commandText, params object[] paramList) { SQLiteCommand cmd = cn.CreateCommand(); cmd.CommandText = commandText; AttachParameters(cmd,commandText, paramList); if (cn.State == ConnectionState.Closed) cn.Open(); int result = cmd.ExecuteNonQuery(); cmd.Dispose(); cn.Close(); return result; } /// <summary> /// Executes non-query sql Statment with Transaction /// </summary> /// <param name="transaction">SQLiteTransaction. Transaction consists of Connection, Transaction, /// and Command, all of which must be created prior to making this method call. </param> /// <param name="commandText">Command text.</param> /// <param name="paramList">Param list.</param> /// <returns>Integer</returns> /// <remarks>user must examine Transaction Object and handle transaction.connection .Close, etc.</remarks> public static int ExecuteNonQuery(SQLiteTransaction transaction, string commandText, params object[] paramList) { if (transaction == null) throw new ArgumentNullException("transaction"); if (transaction != null && transaction.Connection == null) throw new ArgumentException("The transaction was rolled back or committed, please provide an open transaction.", "transaction"); IDbCommand cmd = transaction.Connection.CreateCommand(); cmd.CommandText = commandText; AttachParameters((SQLiteCommand)cmd,cmd.CommandText, paramList); if (transaction.Connection.State == ConnectionState.Closed) transaction.Connection.Open(); int result = cmd.ExecuteNonQuery(); cmd.Dispose(); return result; } /// <summary> /// Executes the non query. /// </summary> /// <param name="cmd">CMD.</param> /// <returns></returns> public static int ExecuteNonQuery(IDbCommand cmd) { if (cmd.Connection.State == ConnectionState.Closed) cmd.Connection.Open(); int result = cmd.ExecuteNonQuery(); cmd.Connection.Close(); cmd.Dispose(); return result; } /// <summary> /// Shortcut to ExecuteScalar with Sql Statement embedded params and object[] param values /// </summary> /// <param name="connectionString">SQLite Connection String</param> /// <param name="commandText">SQL statment with embedded "@param" style parameters</param> /// <param name="paramList">object[] array of param values</param> /// <returns></returns> public static object ExecuteScalar(string connectionString, string commandText, params object[] paramList) { SQLiteConnection cn = new SQLiteConnection(connectionString); SQLiteCommand cmd = cn.CreateCommand(); cmd.CommandText = commandText; AttachParameters(cmd,commandText, paramList); if (cn.State == ConnectionState.Closed) cn.Open(); object result = cmd.ExecuteScalar(); cmd.Dispose(); cn.Close(); return result; } /// <summary> /// Execute XmlReader with complete Command /// </summary> /// <param name="command">SQLite Command</param> /// <returns>XmlReader</returns> public static XmlReader ExecuteXmlReader(IDbCommand command) { // open the connection if necessary, but make sure we // know to close it when we�re done. if (command.Connection.State != ConnectionState.Open) { command.Connection.Open(); } // get a data adapter SQLiteDataAdapter da = new SQLiteDataAdapter((SQLiteCommand)command); DataSet ds = new DataSet(); // fill the data set, and return the schema information da.MissingSchemaAction = MissingSchemaAction.AddWithKey; da.Fill(ds); // convert our dataset to XML StringReader stream = new StringReader(ds.GetXml()); command.Connection.Close(); // convert our stream of text to an XmlReader return new XmlTextReader(stream); } /// <summary> /// Parses parameter names from SQL Statement, assigns values from object array , /// and returns fully populated ParameterCollection. /// </summary> /// <param name="commandText">Sql Statement with "@param" style embedded parameters</param> /// <param name="paramList">object[] array of parameter values</param> /// <returns>SQLiteParameterCollection</returns> /// <remarks>Status experimental. Regex appears to be handling most issues. Note that parameter object array must be in same ///order as parameter names appear in SQL statement.</remarks> private static SQLiteParameterCollection AttachParameters(SQLiteCommand cmd, string commandText, params object[] paramList) { if (paramList == null || paramList.Length == 0) return null; SQLiteParameterCollection coll = cmd.Parameters; string parmString = commandText.Substring(commandText.IndexOf("@")); // pre-process the string so always at least 1 space after a comma. parmString = parmString.Replace(",", " ,"); // get the named parameters into a match collection string pattern = @"(@)S*(.*?)"; Regex ex = new Regex(pattern, RegexOptions.IgnoreCase); MatchCollection mc = ex.Matches(parmString); string[] paramNames = new string[mc.Count]; int i = 0; foreach (Match m in mc) { paramNames[i] = m.Value; i++; } // now let's type the parameters int j = 0; Type t = null; foreach (object o in paramList) { t = o.GetType(); SQLiteParameter parm = new SQLiteParameter(); switch (t.ToString()) { case ("DBNull"): case ("Char"): case ("SByte"): case ("UInt16"): case ("UInt32"): case ("UInt64"): throw new SystemException("Invalid data type"); case ("System.String"): parm.DbType = DbType.String; parm.ParameterName = paramNames[j]; parm.Value = (string)paramList[j]; coll.Add(parm); break; case ("System.Byte[]"): parm.DbType = DbType.Binary; parm.ParameterName = paramNames[j]; parm.Value = (byte[])paramList[j]; coll.Add(parm); break; case ("System.Int32"): parm.DbType = DbType.Int32; parm.ParameterName = paramNames[j]; parm.Value = (int)paramList[j]; coll.Add(parm); break; case ("System.Boolean"): parm.DbType = DbType.Boolean; parm.ParameterName = paramNames[j]; parm.Value = (bool)paramList[j]; coll.Add(parm); break; case ("System.DateTime"): parm.DbType = DbType.DateTime; parm.ParameterName = paramNames[j]; parm.Value = Convert.ToDateTime(paramList[j]); coll.Add(parm); break; case ("System.Double"): parm.DbType = DbType.Double; parm.ParameterName = paramNames[j]; parm.Value = Convert.ToDouble(paramList[j]); coll.Add(parm); break; case ("System.Decimal"): parm.DbType = DbType.Decimal; parm.ParameterName = paramNames[j]; parm.Value = Convert.ToDecimal(paramList[j]); break; case ("System.Guid"): parm.DbType = DbType.Guid; parm.ParameterName = paramNames[j]; parm.Value = (System.Guid)(paramList[j]); break; case ("System.Object"): parm.DbType = DbType.Object; parm.ParameterName = paramNames[j]; parm.Value = paramList[j]; coll.Add(parm); break; default: throw new SystemException("Value is of unknown data type"); } // end switch j++; } return coll; } /// <summary> /// Executes non query typed params from a DataRow /// </summary> /// <param name="command">Command.</param> /// <param name="dataRow">Data row.</param> /// <returns>Integer result code</returns> public static int ExecuteNonQueryTypedParams(IDbCommand command, DataRow dataRow) { int retVal = 0; // If the row has values, the store procedure parameters must be initialized if (dataRow != null && dataRow.ItemArray.Length > 0) { // Set the parameters values AssignParameterValues(command.Parameters, dataRow); retVal = ExecuteNonQuery(command); } else { retVal = ExecuteNonQuery(command); } return retVal; } /// <summary> /// This method assigns dataRow column values to an IDataParameterCollection /// </summary> /// <param name="commandParameters">The IDataParameterCollection to be assigned values</param> /// <param name="dataRow">The dataRow used to hold the command's parameter values</param> /// <exception cref="System.InvalidOperationException">Thrown if any of the parameter names are invalid.</exception> protected internal static void AssignParameterValues(IDataParameterCollection commandParameters, DataRow dataRow) { if (commandParameters == null || dataRow == null) { // Do nothing if we get no data return; } DataColumnCollection columns = dataRow.Table.Columns; int i = 0; // Set the parameters values foreach (IDataParameter commandParameter in commandParameters) { // Check the parameter name if (commandParameter.ParameterName == null || commandParameter.ParameterName.Length <= 1) throw new InvalidOperationException(string.Format( "Please provide a valid parameter name on the parameter #{0}, the ParameterName property has the following value: '{1}'.", i, commandParameter.ParameterName)); if (columns.Contains(commandParameter.ParameterName)) commandParameter.Value = dataRow[commandParameter.ParameterName]; else if (columns.Contains(commandParameter.ParameterName.Substring(1))) commandParameter.Value = dataRow[commandParameter.ParameterName.Substring(1)]; i++; } } /// <summary> /// This method assigns dataRow column values to an array of IDataParameters /// </summary> /// <param name="commandParameters">Array of IDataParameters to be assigned values</param> /// <param name="dataRow">The dataRow used to hold the stored procedure's parameter values</param> /// <exception cref="System.InvalidOperationException">Thrown if any of the parameter names are invalid.</exception> protected void AssignParameterValues(IDataParameter[] commandParameters, DataRow dataRow) { if ((commandParameters == null) || (dataRow == null)) { // Do nothing if we get no data return; } DataColumnCollection columns = dataRow.Table.Columns; int i = 0; // Set the parameters values foreach (IDataParameter commandParameter in commandParameters) { // Check the parameter name if (commandParameter.ParameterName == null || commandParameter.ParameterName.Length <= 1) throw new InvalidOperationException(string.Format( "Please provide a valid parameter name on the parameter #{0}, the ParameterName property has the following value: '{1}'.", i, commandParameter.ParameterName)); if (columns.Contains(commandParameter.ParameterName)) commandParameter.Value = dataRow[commandParameter.ParameterName]; else if (columns.Contains(commandParameter.ParameterName.Substring(1))) commandParameter.Value = dataRow[commandParameter.ParameterName.Substring(1)]; i++; } } /// <summary> /// This method assigns an array of values to an array of IDataParameters /// </summary> /// <param name="commandParameters">Array of IDataParameters to be assigned values</param> /// <param name="parameterValues">Array of objects holding the values to be assigned</param> /// <exception cref="System.ArgumentException">Thrown if an incorrect number of parameters are passed.</exception> protected void AssignParameterValues(IDataParameter[] commandParameters, params object[] parameterValues) { if ((commandParameters == null) || (parameterValues == null)) { // Do nothing if we get no data return; } // We must have the same number of values as we pave parameters to put them in if (commandParameters.Length != parameterValues.Length) { throw new ArgumentException("Parameter count does not match Parameter Value count."); } // Iterate through the IDataParameters, assigning the values from the corresponding position in the // value array for (int i = 0, j = commandParameters.Length, k = 0; i < j; i++) { if (commandParameters[i].Direction != ParameterDirection.ReturnValue) { // If the current array value derives from IDataParameter, then assign its Value property if (parameterValues[k] is IDataParameter) { IDataParameter paramInstance; paramInstance = (IDataParameter)parameterValues[k]; if (paramInstance.Direction == ParameterDirection.ReturnValue) { paramInstance = (IDataParameter)parameterValues[++k]; } if (paramInstance.Value == null) { commandParameters[i].Value = DBNull.Value; } else { commandParameters[i].Value = paramInstance.Value; } } else if (parameterValues[k] == null) { commandParameters[i].Value = DBNull.Value; } else { commandParameters[i].Value = parameterValues[k]; } k++; } } } } }
希望本文所述对大家的C#程序设计有所帮助。
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