把做工程过程中重要的内容段备份一次，如下内容是关于C#封装的Sqlite访问类的内容，希望能对各位有一些用途。

using System;using System.Collections;using System.Collections.Specialized;using System.Data;using System.Configuration;using System.Data.SQLite;namespace DAL{ internal abstract class DbHelperSQLite { public static string connectionString = "Data Source=" + AppDomain.CurrentDomain.BaseDirectory + @"dataleaf.db;Version=3;"; public DbHelperSQLite() { } #region 公用方法 public static int GetMaxID(string FieldName, string TableName) { string strsql = "select max(" + FieldName + ")+1 from " + TableName; object obj = GetSingle(strsql); if (obj == null) { return 1; } else { return int.Parse(obj.ToString()); } } public static bool Exists(string strSql) { object obj = GetSingle(strSql); int cmdresult; if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value))) { cmdresult = 0; } else { cmdresult = int.Parse(obj.ToString()); } if (cmdresult == 0) { return false; } else { return true; } } public static bool Exists(string strSql, params SQLiteParameter[] cmdParms) { object obj = GetSingle(strSql, cmdParms); int cmdresult; if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value))) { cmdresult = 0; } else { cmdresult = int.Parse(obj.ToString()); } if (cmdresult == 0) { return false; } else { return true; } } #endregion #region 执行简单SQL语句 public static int ExecuteSql(string SQLString) { using (SQLiteConnection connection = new SQLiteConnection(connectionString)) { using (SQLiteCommand cmd = new SQLiteCommand(SQLString, connection)) { try { connection.Open(); int rows = cmd.ExecuteNonQuery(); return rows; } catch (System.Data.SQLite.SQLiteException E) { connection.Close(); throw new Exception(E.Message); } } } } public static void ExecuteSqlTran(ArrayList SQLStringList) { using (SQLiteConnection conn = new SQLiteConnection(connectionString)) { conn.Open(); SQLiteCommand cmd = new SQLiteCommand(); cmd.Connection = conn; SQLiteTransaction tx = conn.BeginTransaction(); cmd.Transaction = tx; try { for (int n = 0; n < SQLStringList.Count; n++) { string strsql = SQLStringList[n].ToString(); if (strsql.Trim().Length > 1) { cmd.CommandText = strsql; cmd.ExecuteNonQuery(); } } tx.Commit(); } catch (System.Data.SQLite.SQLiteException E) { tx.Rollback(); throw new Exception(E.Message); } } } public static int ExecuteSql(string SQLString, string content) { using (SQLiteConnection connection = new SQLiteConnection(connectionString)) { SQLiteCommand cmd = new SQLiteCommand(SQLString, connection); SQLiteParameter myParameter = new SQLiteParameter("@content", DbType.String); myParameter.Value = content; cmd.Parameters.Add(myParameter); try { connection.Open(); int rows = cmd.ExecuteNonQuery(); return rows; } catch (System.Data.SQLite.SQLiteException E) { throw new Exception(E.Message); } finally { cmd.Dispose(); connection.Close(); } } } public static int ExecuteSqlInsertImg(string strSQL, byte[] fs) { using (SQLiteConnection connection = new SQLiteConnection(connectionString)) { SQLiteCommand cmd = new SQLiteCommand(strSQL, connection); SQLiteParameter myParameter = new SQLiteParameter("@fs", DbType.Binary); myParameter.Value = fs; cmd.Parameters.Add(myParameter); try { connection.Open(); int rows = cmd.ExecuteNonQuery(); return rows; } catch (System.Data.SQLite.SQLiteException E) { throw new Exception(E.Message); } finally { cmd.Dispose(); connection.Close(); } } } public static object GetSingle(string SQLString) { using (SQLiteConnection connection = new SQLiteConnection(connectionString)) { using (SQLiteCommand cmd = new SQLiteCommand(SQLString, connection)) { try { connection.Open(); object obj = cmd.ExecuteScalar(); if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value))) { return null; } else { return obj; } } catch (System.Data.SQLite.SQLiteException e) { connection.Close(); throw new Exception(e.Message); } } } } public static SQLiteDataReader ExecuteReader(string strSQL) { SQLiteConnection connection = new SQLiteConnection(connectionString); SQLiteCommand cmd = new SQLiteCommand(strSQL, connection); try { connection.Open(); SQLiteDataReader myReader = cmd.ExecuteReader(); return myReader; } catch (System.Data.SQLite.SQLiteException e) { throw new Exception(e.Message); } } public static DataSet Query(string SQLString) { using (SQLiteConnection connection = new SQLiteConnection(connectionString)) { DataSet ds = new DataSet(); try { connection.Open(); SQLiteDataAdapter command = new SQLiteDataAdapter(SQLString, connection); command.Fill(ds, "ds"); } catch (System.Data.SQLite.SQLiteException ex) { throw new Exception(ex.Message); } return ds; } } #endregion #region 执行带参数的SQL语句 public static int ExecuteSql(string SQLString, params SQLiteParameter[] cmdParms) { using (SQLiteConnection connection = new SQLiteConnection(connectionString)) { using (SQLiteCommand cmd = new SQLiteCommand()) { try { PrepareCommand(cmd, connection, null, SQLString, cmdParms); int rows = cmd.ExecuteNonQuery(); cmd.Parameters.Clear(); return rows; } catch (System.Data.SQLite.SQLiteException E) { throw new Exception(E.Message); } } } } public static void ExecuteSqlTran(Hashtable SQLStringList) { using (SQLiteConnection conn = new SQLiteConnection(connectionString)) { conn.Open(); using (SQLiteTransaction trans = conn.BeginTransaction()) { SQLiteCommand cmd = new SQLiteCommand(); try { foreach (DictionaryEntry myDE in SQLStringList) { string cmdText = myDE.Key.ToString(); SQLiteParameter[] cmdParms = (SQLiteParameter[])myDE.Value; PrepareCommand(cmd, conn, trans, cmdText, cmdParms); int val = cmd.ExecuteNonQuery(); cmd.Parameters.Clear(); trans.Commit(); } } catch { trans.Rollback(); throw; } } } } public static object GetSingle(string SQLString, params SQLiteParameter[] cmdParms) { using (SQLiteConnection connection = new SQLiteConnection(connectionString)) { using (SQLiteCommand cmd = new SQLiteCommand()) { try { PrepareCommand(cmd, connection, null, SQLString, cmdParms); object obj = cmd.ExecuteScalar(); cmd.Parameters.Clear(); if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value))) { return null; } else { return obj; } } catch (System.Data.SQLite.SQLiteException e) { throw new Exception(e.Message); } } } } public static SQLiteDataReader ExecuteReader(string SQLString, params SQLiteParameter[] cmdParms) { SQLiteConnection connection = new SQLiteConnection(connectionString); SQLiteCommand cmd = new SQLiteCommand(); try { PrepareCommand(cmd, connection, null, SQLString, cmdParms); SQLiteDataReader myReader = cmd.ExecuteReader(); cmd.Parameters.Clear(); return myReader; } catch (System.Data.SQLite.SQLiteException e) { throw new Exception(e.Message); } } public static DataSet Query(string SQLString, params SQLiteParameter[] cmdParms) { using (SQLiteConnection connection = new SQLiteConnection(connectionString)) { SQLiteCommand cmd = new SQLiteCommand(); PrepareCommand(cmd, connection, null, SQLString, cmdParms); using (SQLiteDataAdapter da = new SQLiteDataAdapter(cmd)) { DataSet ds = new DataSet(); try { da.Fill(ds, "ds"); cmd.Parameters.Clear(); } catch (System.Data.SQLite.SQLiteException ex) { throw new Exception(ex.Message); } return ds; } } } private static void PrepareCommand(SQLiteCommand cmd, SQLiteConnection conn, SQLiteTransaction trans, string cmdText, SQLiteParameter[] cmdParms) { if (conn.State != ConnectionState.Open) conn.Open(); cmd.Connection = conn; cmd.CommandText = cmdText; if (trans != null) cmd.Transaction = trans; if (cmdParms != null) { foreach (SQLiteParameter parm in cmdParms) cmd.Parameters.Add(parm); } } #endregion }}