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;
 }
 }
 }
 }
}