C# PGSQL 关于SQL参数的例示

工作关系 同时使用SQL SERVER 与Postgresql 数据库，

            clientChar = txtClientChar.Text.Trim();
            sql = "select client_id,client_code,name,client_level_id,client_custom_options_ids, area_id,location ";
            sql += " from client where client_code = @pClient_Code or name like @pName";
            NpgsqlParameter[] sqlPara = new NpgsqlParameter[2];
            //pgsql 的参数与SQL SERVER 的格式不一样
            sqlPara[0] = new NpgsqlParameter("@pClient_Code", NpgsqlTypes.NpgsqlDbType.Text,20);
            sqlPara[0].Value = clientChar;
            sqlPara[1] = new NpgsqlParameter("@pName", NpgsqlTypes.NpgsqlDbType.Text,100);
            sqlPara[1].Value = '%' + clientChar + '%';
            DataTable dt = DBHelperPg.ExecuteDataTable(sql, sqlPara);
            dataGridView1.DataSource = dt;

附：DBHelperpg.cs

 class DBHelperPg
    {

        public static string ConnectionString = ConfigurationManager.AppSettings["postgre"].ToString();


        /// <summary>  
        /// 执行SQL语句  
        /// </summary>  
        /// <param name="sql">SQL</param>  
        /// <returns>成功返回大于0的数字</returns>  
        public static int ExecuteSQL(string sql)
        {
            int num2 = -1;
            using (NpgsqlConnection connection = new NpgsqlConnection(ConnectionString))
            {
                using (NpgsqlCommand command = new NpgsqlCommand(sql, connection))
                {
                    try
                    {
                        connection.Open();
                        num2 = command.ExecuteNonQuery();
                    }
                    catch (NpgsqlException exception)
                    {
                        throw new Exception(exception.Message);
                    }
                    finally
                    {
                        connection.Close();
                    }
                }
            }
            return num2;
        }

        //带参数的执行查询，不返回结果，返回影响行数
        //执行SQL语句并返回受影响的行数
        public static int ExecuteNonQuery(string sql, params NpgsqlParameter[] parameters)
        {
            using (NpgsqlConnection conn = new NpgsqlConnection(ConnectionString))
            {
                conn.Open();
                using (NpgsqlCommand cmd = conn.CreateCommand())
                {
                    cmd.CommandText = sql;
                    //foreach (SqlParameter param in parameters)
                    //{
                    //    cmd.Parameters.Add(param);
                    //}
                    cmd.Parameters.AddRange(parameters);
                    return cmd.ExecuteNonQuery();
                }
            }
        }

        //执行查询，并返回查询所返回的结果集中第一行的第一列。忽略额外的列或行。
        public static object ExecuteScalar(string sql, params NpgsqlParameter[] parameters)
        {
            using (NpgsqlConnection conn = new NpgsqlConnection(ConnectionString))
            {
                conn.Open();
                using (NpgsqlCommand cmd = conn.CreateCommand())
                {
                    cmd.CommandText = sql;
                    cmd.Parameters.AddRange(parameters);
                    return cmd.ExecuteScalar();

                }
            }
        }




        //查询并返回结果集DataTable,一般只用来执行查询结果比较少的sql。
        public static DataTable ExecuteDataTable(string sql, params NpgsqlParameter[] parameters)
        {
            using (NpgsqlConnection conn = new NpgsqlConnection(ConnectionString))
            {
                conn.Open();
                using (NpgsqlCommand cmd = conn.CreateCommand())
                {
                    cmd.CommandText = sql;
                    cmd.Parameters.AddRange(parameters);

                    NpgsqlDataAdapter adapter = new NpgsqlDataAdapter(cmd);
                    DataSet dataset = new DataSet();
                    adapter.Fill(dataset);
                    return dataset.Tables[0];
                }
            }

            //查询较大的数据用 DateRead()，但应尽可能用分页数据，仍然用datatable更好。
        }
    }