C#封装的Sqlite访问类
C#封装的Sqlite访问类，要访问Sqlite这下简单了，直接调用此类中的方法即可
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 /// <summary> /// 执行SQL语句，返回影响的记录数 /// </summary> /// <param name="SQLString">SQL语句</param> /// <returns>影响的记录数</returns> 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); } } } } /// <summary> /// 执行多条SQL语句，实现数据库事务。 /// </summary> /// <param name="SQLStringList">多条SQL语句</param> 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); } } } /// <summary> /// 执行带一个存储过程参数的的SQL语句。 /// </summary> /// <param name="SQLString">SQL语句</param> /// <param name="content">参数内容,比如一个字段是格式复杂的文章，有特殊符号，可以通过这个方式添加</param> /// <returns>影响的记录数</returns> 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(); } } } /// <summary> /// 向数据库里插入图像格式的字段(和上面情况类似的另一种实例) /// </summary> /// <param name="strSQL">SQL语句</param> /// <param name="fs">图像字节,数据库的字段类型为image的情况</param> /// <returns>影响的记录数</returns> 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(); } } } /// <summary> /// 执行一条计算查询结果语句，返回查询结果（object）。 /// </summary> /// <param name="SQLString">计算查询结果语句</param> /// <returns>查询结果（object）</returns> 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); } } } } /// <summary> /// 执行查询语句，返回SQLiteDataReader /// </summary> /// <param name="strSQL">查询语句</param> /// <returns>SQLiteDataReader</returns> 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); } } /// <summary> /// 执行查询语句，返回DataSet /// </summary> /// <param name="SQLString">查询语句</param> /// <returns>DataSet</returns> 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 /// <summary> /// 执行SQL语句，返回影响的记录数 /// </summary> /// <param name="SQLString">SQL语句</param> /// <returns>影响的记录数</returns> 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); } } } } /// <summary> /// 执行多条SQL语句，实现数据库事务。 /// </summary> /// <param name="SQLStringList">SQL语句的哈希表（key为sql语句，value是该语句的SQLiteParameter[]）</param> public static void ExecuteSqlTran(Hashtable SQLStringList) { using (SQLiteConnection conn = new SQLiteConnection(connectionString)) { conn.Open(); using (SQLiteTransaction trans = conn.BeginTransaction()) { SQLiteCommand cmd = new SQLiteCommand(); try { //循环 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; } } } } /// <summary> /// 执行一条计算查询结果语句，返回查询结果（object）。 /// </summary> /// <param name="SQLString">计算查询结果语句</param> /// <returns>查询结果（object）</returns> 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); } } } } /// <summary> /// 执行查询语句，返回SQLiteDataReader /// </summary> /// <param name="strSQL">查询语句</param> /// <returns>SQLiteDataReader</returns> 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); } } /// <summary> /// 执行查询语句，返回DataSet /// </summary> /// <param name="SQLString">查询语句</param> /// <returns>DataSet</returns> 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; cmd.CommandType = CommandType.Text;//cmdType; if (cmdParms != null) { foreach (SQLiteParameter parm in cmdParms) cmd.Parameters.Add(parm); } } #endregion } }