如何从函数（存储过程）中获取 INOUT 值？与GOLAN

Question

ALL 如何从函数（存储过程）中获取 INOUT 参数值，因此，我想获取 v_id 的值：CREATE OR REPLACE FUNCTION mytest(    IN v_name character varying,    INOUT v_id bigint)  RETURNS bigint AS$BODY$      Begin          v_id := 99;        select  v_name;        return ;    END;    $BODY$  LANGUAGE plpgsql VOLATILE  COST 100;当我调用这个 func 时，看看这个，我使用了 github.com/lib/pq 中的库，我的程序出现了恐慌：  func main() {    dbstring := "user=postgres dbname=xxx password=xxx host=127.0.0.1            port=5432  sslmode=disable"    db, err := sql.Open("postgres", dbstring)       db.SetMaxIdleConns(4)    db.SetMaxOpenConns(10)    if err != nil {        panic(err)    }var mynum int64 = 0var s stringa, err2 :=  db.Query("SELECT mytest($1::TEXT,$2::bigint)","lihao",mynum)if err2 != nil {    fmt.Fprintln(os.Stderr, "Error sending mytest:", err)    //os.Exit(1)}else{    fmt.Fprintln(os.Stdout, "a is:",a)    fmt.Fprintln(os.Stdout, "mynum is:",mynum)}for a.Next() {    err = a.Scan(&s, &mynum)    if err != nil {        panic(err)    }   fmt.Fprintln(os.Stdout, "mynum is:",mynum) }}这是恐慌，所以在这里：D:\Go>fs_con.exeError sending mytest: panic: runtime error: invalid memory address or nil pointer dereference[signal 0xc0000005 code=0x0 addr=0x20 pc=0x48d4b9]goroutine 1 [running]:database/sql.(*Rows).Next(0x0, 0xc082028018)c:/go/src/database/sql/sql.go:1633 +0x29main.main()D:/Go/fs_con.go:35 +0x48dgoroutine 5 [chan receive]:database/sql.(*DB).connectionOpener(0xc0820683c0)c:/go/src/database/sql/sql.go:634 +0x4ccreated by database/sql.Openc:/go/src/database/sql/sql.go:481 +0x33d

Answer 1

您的函数不知道返回什么结果。并且最好在函数中添加新变量。

CREATE OR REPLACE FUNCTION mytest(

    IN v_name character varying,

    IN v_id bigint)

  RETURNS bigint AS

$BODY$  

  DECLARE

    result bigint;

  BEGIN  

    result := v_id + 1;

    return result;

  END;

$BODY$

LANGUAGE plpgsql VOLATILE

COST 100;