使用REF_CURSOR转换Oracle存储过程并将全局变量打包到Postgresql或MySQL

Question

该软件包使用Oracle的两个独特功能,REF_CURSOR和包全局变量.我想将功能从Oracle移植到Postgresql或MySQL.

PACKAGE tox IS
    /*=======================*/
        g_spool_key spool.key%TYPE := NULL;
        TYPE t_spool IS REF CURSOR RETURN spool%ROWTYPE;
    /*=======================*/
        PROCEDURE begin_spool;
    /*=======================*/
        PROCEDURE into_spool
            (
            in_txt IN spool.txt%TYPE
            );
    /*=======================*/
        PROCEDURE reset_spool;
    /*=======================*/
        FUNCTION end_spool
            RETURN t_spool;
    /*=======================*/
        FUNCTION timestamp
            RETURN VARCHAR2;
    /*=======================*/
    END tox;

PACKAGE BODY tox
    IS
    /*========================================================================*/
    PROCEDURE begin_spool
        AS
        /*=======================*/
        BEGIN
        /*=======================*/
            SELECT
                key.NEXTVAL
            INTO
                g_spool_key
            FROM
                DUAL;
        /*=======================*/
        END begin_spool;
    /*========================================================================*/
    PROCEDURE into_spool
        (
        in_txt IN spool.txt%TYPE
        )
        AS
        /*=======================*/
        BEGIN
        /*=======================*/
            INSERT INTO
                spool
            VALUES
                (
                g_spool_key,
                in_txt,
                seq.NEXTVAL
                );
        /*=======================*/
        END into_spool;
    /*========================================================================*/
    PROCEDURE reset_spool
        AS
        /*=======================*/
        BEGIN
        /*=======================*/
            DELETE
                spool
            WHERE
                key = g_spool_key;
            COMMIT;
            begin_spool;
        /*=======================*/
        END reset_spool;
    /*========================================================================*/
    FUNCTION end_spool
        RETURN t_spool
        AS
        v_spool t_spool;
        /*=======================*/
        BEGIN
        /*=======================*/
            COMMIT;
            OPEN v_spool FOR
                SELECT
                    *
                FROM
                    spool
                WHERE
                    key = g_spool_key
                ORDER BY
                    seq;
            RETURN v_spool;
        /*=======================*/
        END end_spool;
    /*========================================================================*/
    FUNCTION timestamp
        RETURN VARCHAR2
        AS
        /*-----------------------*/
        v_result VARCHAR2(14);
        /*=======================*/
        BEGIN
        /*=======================*/
            SELECT
                TO_CHAR(SYSDATE,'YYYYMMDDHH24MISS')
            INTO
                v_result
            FROM
                DUAL;
            RETURN v_result;
        /*=======================*/
        END timestamp;
    /*========================================================================*/
    END tox;

你能生成相同的代码吗？对于Postgresql？对于MySQL？

注意:Oracle代码是线程安全的.这是一个关键功能.

Answer 1

PostgreSQL 8.3

PostgreSQL中的问题是缺少全局(或包)变量,因此必须使用首先创建的临时表来解决该部分.其余部分非常简单.

如果您认真地将应用程序移植到PostgreSQL或MySQL,我会建议您不要使用全局变量,因为它们在编码时是不好的做法(至少根据我:))

但无论如何,这里是代码:

这必须在运行函数之前存在:

create table spool (key integer, txt varchar(2048), seq integer);
create sequence s_key;
create sequence s_seq;
create schema tox;
create temp table globals (name varchar(10), value varchar(100), primary key(name));

这些函数被放在模式tox中以模拟包.

create or replace function tox.get_variable(var_name varchar) returns varchar as $$
declare 
    ret_val varchar(100);
begin
    select value into ret_val from globals where name = var_name;
    return ret_val;
end
$$ language plpgsql;

create or replace function tox.set_variable(var_name varchar, value anyelement) returns void as $$
begin
    delete from globals where name = var_name;
    insert into globals values(var_name, value);
end;
$$ language plpgsql;


create or replace function tox.begin_spool() returns integer as $$
begin
    perform tox.set_variable('key', nextval('s_key')::varchar);
    return tox.get_variable('key'); 
end;
$$ language plpgsql;

create or replace function tox.reset_spool() returns integer as $$
begin
    delete from spool where key = tox.get_variable('key')::integer;
    return tox.begin_spool();
end;
$$ language plpgsql;

create or replace function tox.into_spool(in_txt spool.txt%TYPE) returns void as $$
begin
    insert into spool values(tox.get_variable('key')::integer, in_txt, nextval('s_seq'));
end;
$$ language plpgsql;



create or replace function tox.end_spool(refcursor) returns refcursor as $$
declare
begin
    open $1 for select * from spool where key = tox.get_variable('key')::integer order by seq;
    return $1;
end;
$$ language plpgsql;



create or replace function tox.test(txt varchar(100)) returns setof spool as $$
declare 
    v_spool_key integer;
    cnt integer;
begin
    v_spool_key = tox.begin_spool();

    for cnt in 1..10 loop
    perform tox.into_spool(txt || cnt); 
    end loop;

    perform tox.end_spool('spool_cursor');
    return query fetch all from spool_cursor;
end;
$$ language plpgsql;

要测试,只需在创建完所有内容后运行它.

select * from tox.test('Test');