使用Npgsql庫調用PostgreSQL的函數（存儲過程）

PostgreSQL沒有像SqlServer一樣的存儲過程。他們的標準也不一樣，Sqlserver是T-SQL標準，而PostgreSQL有很多過程語言，其中以 PL/pgSQL最熱。由於我也是初學，就不在這裏跟大家討論語法了。進入主題，模擬實現Sqlserver中的存儲過程

首先，在建好PostgreSQL中的函數（PostgreSQL中過程用函數來實現），代碼如下：

CREATE OR REPLACE FUNCTION "public"."userreg" (p_passport varchar, p_nickname varchar, out p_password varchar, out p_userid integer) RETURNS record AS
$body$
declare
tmpstr varchar(32);
begin
$3 := NULL;
$4 := NULL;
 if exists(select 1 from public.t_user where passport = $1) then
    begin
     $4:=-1;
     end;
    else
     begin
         $3 := cast ((round((random()+1)   * 9999999))  as varchar(20));
         tmpstr := md5($3);
           insert into public.t_user (passport,password,nickname) values($1,tmpstr,$2);
          $4:=(select userid from public.t_user where passport = $1);
     end;
    end if;
    EXCEPTION
     WHEN others THEN
           $4:=-2;
        $3:=-2;
en d;
$body$
LANGUAGE 'plpgsql' VOLATILE CALLED ON NULL INPUT SECURITY INVOKER;

以上示例代碼，模擬SqlServer，所以故意加入了兩個In參數和兩OUT參數。

下面是在.net下的調用代碼，就跟SQL中的存儲過程調用一樣。ODBC方式貌似不行。

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 public void UserRegiste(T_User user)  
        {  
                        
            NpgsqlConnection conn = new NpgsqlConnection();  
            conn.ConnectionString = "Server=127.0.0.1;Port=5432;Userid=postgres;database=jtnet;password=123456;Protocol=3;SSL=false;Pooling=true;MinPoolSize=1;MaxPoolSize=20;Encoding=UNICODE;Timeout=60;SslMode=Disable";  
            NpgsqlCommand cmd = new NpgsqlCommand();  
            cmd.Connection = conn;  
            cmd.CommandType = CommandType.StoredProcedure;  
            cmd.CommandText = "userreg";  
            NpgsqlParameter p1 = new NpgsqlParameter("p_passport", DbType.String, 50);  
            NpgsqlParameter p2 = new NpgsqlParameter("p_nickname", DbType.String, 50);  
            NpgsqlParameter p3 = new NpgsqlParameter("p_nickname", DbType.Int32);  
            NpgsqlParameter p4 = new NpgsqlParameter("p_userid", DbType.Int32);  
            p1.Value = user.Passport;  
            p2.Value = user.UserNickName;  
            p3.Direction = ParameterDirection.Output;  
            p4.Direction = ParameterDirection.Output;  
            cmd.Parameters.Add(p1);  
            cmd.Parameters.Add(p2);  
            cmd.Parameters.Add(p3);  
            cmd.Parameters.Add(p4);  
            conn.Open();  
            NpgsqlDataReader dr =  cmd.ExecuteReader();  
            dr.Read();  
            //此處可以寫上顯示代碼  
｝ 
 public void UserRegiste(T_User user)
        {
                     
            NpgsqlConnection conn = new NpgsqlConnection();
            conn.ConnectionString = "Server=127.0.0.1;Port=5432;Userid=postgres;database=jtnet;password=123456;Protocol=3;SSL=false;Pooling=true;MinPoolSize=1;MaxPoolSize=20;Encoding=UNICODE;Timeout=60;SslMode=Disable";
            NpgsqlCommand cmd = new NpgsqlCommand();
            cmd.Connection = conn;
            cmd.CommandType = CommandType.StoredProcedure;
            cmd.CommandText = "userreg";
            NpgsqlParameter p1 = new NpgsqlParameter("p_passport", DbType.String, 50);
            NpgsqlParameter p2 = new NpgsqlParameter("p_nickname", DbType.String, 50);
            NpgsqlParameter p3 = new NpgsqlParameter("p_nickname", DbType.Int32);
            NpgsqlParameter p4 = new NpgsqlParameter("p_userid", DbType.Int32);
            p1.Value = user.Passport;
            p2.Value = user.UserNickName;
            p3.Direction = ParameterDirection.Output;
            p4.Direction = ParameterDirection.Output;
            cmd.Parameters.Add(p1);
            cmd.Parameters.Add(p2);
            cmd.Parameters.Add(p3);
            cmd.Parameters.Add(p4);
            conn.Open();
            NpgsqlDataReader dr =  cmd.ExecuteReader();
            dr.Read();
            //此處可以寫上顯示代碼
｝