SQLite帮助类SQlitehelper 实现对SQLite数据的增删改查

 public class SQLiteHelper
    {

        public const string sConn = "Data Source=" + @"path";

        /// <summary>
        /// 查询，返回object ,得到查询结果的首行首列的值，若没有首行首列返回NUll
        /// </summary>
        /// <param name="sql">查询语句</param>
        /// <param name="parameters">可选参数</param>
        /// <returns></returns>
        public static object ExecuteScalar(string sql, params SQLiteParameter[] parameters)
        {
            return ExecuteScalar(sql, CommandType.Text, parameters);

        }

        /// <summary>
        /// 查询，返回object  ，执行SQl语句，得到查询结果的首行首列，若没有首行首列返回null 
        /// </summary>
        /// <param name="sql">查询语句</param>
        /// <param name="type">如何解释命令字符串</param>
        /// <param name="parameters">可选的参数</param>
        /// <returns></returns>
        public static object ExecuteScalar(string sql, CommandType type, params SQLiteParameter[] parameters)
        {
            using (SQLiteConnection conn = new SQLiteConnection(sConn))
            {
                conn.Open();
                SQLiteCommand cmd = new SQLiteCommand(sql, conn);

                cmd.CommandType = type;
                cmd.Parameters.AddRange(parameters);
                object obj = cmd.ExecuteScalar();
                cmd.Parameters.Clear();
                return obj;
            }
        }

      /// <summary>
      /// 执行增、删、改
      /// </summary>
      /// <param name="sql">sql语句</param>
      /// <param name="parameters">可选参数</param>
      /// <returns>返回int 得到受影响的行数</returns>
        public static int ExecuteNonQuery(string sql, params SQLiteParameter[] parameters)
        {
            return ExecuteNonQuery(sql, CommandType.Text, parameters);
        }
        /// <summary>
        /// 执行增、删、改
        /// </summary>
        /// <param name="sql">sql语句</param>
        /// <param name="type">如何解释命令字符串</param>
        /// <param name="parameters">可选参数</param>
        /// <returns></returns>
        public static int ExecuteNonQuery(string sql, CommandType type, params SQLiteParameter[] parameters)
        {
            using (SQLiteConnection conn = new SQLiteConnection(sConn))
            {
                conn.Open();
                SQLiteCommand cmd = new SQLiteCommand(sql, conn);
                cmd.CommandType = type;
                cmd.Parameters.AddRange(parameters);
                int num = cmd.ExecuteNonQuery();
                cmd.Parameters.Clear();
                return num;
            }
        }


        /// <summary>
        /// 断开式查询，查询多个列
        /// </summary>
        /// <param name="sql">sql语句</param>
        /// <param name="parameters">可选参数</param>
        /// <returns>返回DataTable类型</returns>
        public static DataTable ExecuteTable(string sql, params SQLiteParameter[] parameters)
        {
            return ExecuteTable(sql, CommandType.Text, parameters);
        }

        /// <summary>
        /// 断开式查询，查询结果可为多个列
        /// </summary>
        /// <param name="sql">sql语句</param>
        /// <param name="type">如何解释命令字符串</param>
        /// <param name="parameters">可选参数</param>
        /// <returns></returns>
        public static DataTable ExecuteTable(string sql, CommandType type, params SQLiteParameter[] parameters)
        {
            SQLiteConnection conn = new SQLiteConnection(sConn);
            conn.Open();
            SQLiteCommand cmd = new SQLiteCommand(sql, conn);
            cmd.CommandType = type;
            cmd.Parameters.AddRange(parameters);
            SQLiteDataAdapter sda = new SQLiteDataAdapter(cmd);
            DataSet ds = new DataSet();
            sda.Fill(ds);
            conn.Close();
            DataTable dt = ds.Tables[0];
            return dt;
        }
    }