SQLite数据库操作类

首先：添加配置<add key="SQLString" value="~\demo.db"/>  /************************************** * 作用：SQLLite Server操作实现 **************************************/ using System; using System.Collections; using System.Collections.Specialized; using System.Data; using System.Data.SQLite;//这个可以去网上下载 using System.Configuration; public class SQLiteHelper { //数据库连接字符串(web.config来配置)，可以动态更改SQLString支持多数据库. public static string connectionString = "Data Source=" + System.Web.HttpContext.Current.Server.MapPath(ConfigurationManager.AppSettings["SQLString"]); public SQLiteHelper() { } #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SQL语句，设置命令的执行等待时间 /// </summary> /// <param name="SQLString"></param> /// <param name="Times"></param> /// <returns></returns> public static int ExecuteSqlByTime(string SQLString, int Times) { using (SQLiteConnection connection = new SQLiteConnection(connectionString)) { using (SQLiteCommand cmd = new SQLiteCommand(SQLString, connection)) { try { connection.Open(); cmd.CommandTimeout = Times; 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> /// 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 object ExecuteSqlGet(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(); 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) { 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(使用该方法切记要手工关闭SQLiteDataReader和连接) /// </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); } //finally //不能在此关闭，否则，返回的对象将无法使用 //{ // cmd.Dispose(); // connection.Close(); //} } /// <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; } } public static DataSet Query(string SQLString, string TableName) { using (SQLiteConnection connection = new SQLiteConnection(connectionString)) { DataSet ds = new DataSet(); try { connection.Open(); SQLiteDataAdapter command = new SQLiteDataAdapter(SQLString, connection); command.Fill(ds, TableName); } catch (System.Data.SQLite.SQLiteException ex) { throw new Exception(ex.Message); } return ds; } } /// <summary> /// 执行查询语句，返回DataSet,设置命令的执行等待时间 /// </summary> /// <param name="SQLString"></param> /// <param name="Times"></param> /// <returns></returns> public static DataSet Query(string SQLString, int Times) { using (SQLiteConnection connection = new SQLiteConnection(connectionString)) { DataSet ds = new DataSet(); try { connection.Open(); SQLiteDataAdapter command = new SQLiteDataAdapter(SQLString, connection); command.SelectCommand.CommandTimeout = Times; 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 (使用该方法切记要手工关闭SQLiteDataReader和连接) /// </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); } //finally //不能在此关闭，否则，返回的对象将无法使用 //{ // cmd.Dispose(); // connection.Close(); //} } /// <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; } } } public 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 parameter in cmdParms) { if ((parameter.Direction == ParameterDirection.InputOutput || parameter.Direction == ParameterDirection.Input) && (parameter.Value == null)) { parameter.Value = DBNull.Value; } cmd.Parameters.Add(parameter); } } } #endregion #region 参数转换 /// <summary> /// 放回一个SQLiteParameter /// </summary> /// <param name="name">参数名字</param> /// <param name="type">参数类型</param> /// <param name="size">参数大小</param> /// <param name="value">参数值</param> /// <returns>SQLiteParameter的值</returns> public static SQLiteParameter MakeSQLiteParameter(string name, DbType type, int size, object value) { SQLiteParameter parm = new SQLiteParameter(name, type, size); parm.Value = value; return parm; } public static SQLiteParameter MakeSQLiteParameter(string name, DbType type, object value) { SQLiteParameter parm = new SQLiteParameter(name, type); parm.Value = value; return parm; } #endregion }
 调用方法
/// <summary> /// 判断用户是否存在 /// </summary> /// <param name="name">用户名称</param> /// <returns></returns> public bool UserExists(string name) { StringBuilder strSql = new StringBuilder(); strSql.Append("select count(*) n from Users"); strSql.Append(" where UserName=@UserName "); SQLiteParameter[] parameters = { SQLiteHelper.MakeSQLiteParameter("@UserName", DbType.String,30,name)}; return SQLiteHelper.Exists(strSql.ToString(), parameters); } /// <summary> /// 增加一个用户 /// </summary> /// <param name="name">用户名</param> /// <param name="pwd">密码</param> /// <returns></returns> public int CreateUser(string name, string pwd) { int ret = 0; if (!UserExists(name)) { StringBuilder strSql = new StringBuilder(); strSql.Append("insert into t_UserGroup("); strSql.Append("UserName,Password)"); strSql.Append(" values ("); strSql.Append("@UserName,@Password)"); SQLiteParameter[] parameters = { SQLiteHelper.MakeSQLiteParameter("@UserName", DbType.String,30,name), SQLiteHelper.MakeSQLiteParameter("@Password", DbType.String,128,pwd) }; if (SQLiteHelper.ExecuteSql(strSql.ToString(), parameters) >= 1) { ret = 1; } } else { ret = 2; } return ret; } /// <summary> /// 更新一条数据 /// </summary> /// <param name="model">用户分组实体类</param> /// <returns></returns> public bool UpdateUser(int id, string name, string pwd) { StringBuilder strSql = new StringBuilder(); strSql.Append("update Users set "); strSql.Append("UserName=@UserName,"); strSql.Append("Password=@Password"); strSql.Append(" where UserID=@UserID"); SQLiteParameter[] parameters = { SQLiteHelper.MakeSQLiteParameter("@UserID", DbType.Int32,11,id), SQLiteHelper.MakeSQLiteParameter("@UserName", DbType.String,30,name), SQLiteHelper.MakeSQLiteParameter("@Password", DbType.String,128,pwd)}; if (SQLiteHelper.ExecuteSql(strSql.ToString(), parameters) >= 1) { return true; } else { return false; } } /// <summary> /// 删除用户 /// </summary> /// <param name="ID">用户ID</param> /// <returns></returns> public int DeleteUser(int id) { int ret = 0; string strSql3 = "delete from Users where UserID=@UserID"; SQLiteParameter[] parameters = { SQLiteHelper.MakeSQLiteParameter("@UserID", DbType.Int32,4,id)}; if (SQLiteHelper.ExecuteSql(strSql3, parameters) >= 1) { ret = 1; } else { ret = 0; } return ret; } /// <summary> /// 获得用户分组数据列表 /// </summary> /// <param name="strWhere">Where条件</param> /// <returns></returns> public DataSet GetUserList(string strWhere) { StringBuilder strSql = new StringBuilder(); strSql.Append("select * FROM Users "); if (strWhere.Trim() != "") { strSql.Append(" where " + strWhere); } strSql.Append(" order by UserID desc"); return SQLiteHelper.Query(strSql.ToString()); }

注意事项

1. @@IDENTITY LAST_INSERT_ROWID()
2. SELECT cn = COUNT(*) FROM ... SELECT COUNT(*) cn FROM ...
3. LIMIT startIndex,itemCn 这儿的startIndex是从0开始的，而ROW_NUMBER()是从1开始的
4. sqlite中没有SELECT TOP,用LIMIT即可
5. SQLite自增字段，如果在事务中插入数据失败，并不会占用增长后的id，而sql server中对应的id将无效
6. SQLite中没有GETDATE日期函数，在类中加入参数如下DbType.DateTime,DateTime.Now.ToString("s")
7. SQLite支持REPLACE INTO语法,sql server 2008中支持merge to