SQLite数据库操作类

首先：添加配置<addkey="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,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,DbType.String);
            myParameter.Value = content;
            cmd.Parameters.Add(myParameter);
            try
            {
                connection.Open();
                object obj = cmd.ExecuteScalar();
                if ((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,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,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,cmdParms);
                    object obj = cmd.ExecuteScalar();
                    cmd.Parameters.Clear();
                    if ((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,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,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,type);
        parm.Value = value;
        return parm;
    }

    #endregion
}

/// <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",name),SQLiteHelper.MakeSQLiteParameter("@Password",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",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",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

（编辑：李大同）

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