using Npgsql;
using System;
using System.Collections.Generic;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace PGDemo
{
    class Program
    {
        static void Main(string[] args)
        {
            var strSql = "select * from sys_user";
            var dtTemp = PGDBHelper.PostgreTable(strSql);

            strSql = "select id from temp_test ";
            var str = PGDBHelper.GetpostgreExecuteScalar(strSql);

            strSql = "update temp_test set name='wwwwwwww'  where id='1122'";
            var flag = PGDBHelper.PostgreExecuQuery(strSql);
        }

        public class PGDBHelper
        {

            public static string pgsqlConnection = ConfigurationManager.ConnectionStrings["pgsqlConnection"].ConnectionString.ToString();
            /// <summary>
            /// select查询
            /// </summary>
            /// <param name="sql"></param>
            /// <returns></returns>
            public static DataSet PostgreTable(string sql)
            {
                DataSet ds = new DataSet();
                using (NpgsqlConnection conn = new NpgsqlConnection(pgsqlConnection))
                {
                    conn.Open();
                    NpgsqlCommand cmd = new NpgsqlCommand(sql, conn);
                    NpgsqlDataAdapter sda = new NpgsqlDataAdapter(cmd);
                    sda.Fill(ds);
                }
                return ds;
            }

            /// <summary>
            /// 执行sql返回是否成功
            /// </summary>
            /// <param name="?"></param>
            /// <returns></returns>
            public static bool PostgreExecuQuery(string StrText)
            {
                bool bools = false;
                using (NpgsqlConnection conn = new NpgsqlConnection(pgsqlConnection))
                {
                    conn.Open();
                    NpgsqlCommand cmd = new NpgsqlCommand(StrText, conn);
                    int n = cmd.ExecuteNonQuery();
                    conn.Close();
                    bools = n > 0;
                }
                return bools;
            }

            /// <summary>
            /// 执行sql返回字符
            /// </summary>
            /// <param name="strText"></param>
            /// <param name="pgsqlConnection"></param>
            /// <returns></returns>
            public static string GetpostgreExecuteScalar(string strText)
            {
                using (NpgsqlConnection conn = new NpgsqlConnection(pgsqlConnection))
                {
                    conn.Open();
                    NpgsqlCommand cmd = new NpgsqlCommand(strText, conn);
                    string PostgreScalar = cmd.ExecuteScalar().ToString();
                    if (PostgreScalar != null || !string.IsNullOrEmpty(PostgreScalar))
                        return PostgreScalar;
                    else return null;
                }
            }
        }
    }
}