Postgresql中的时间比较逻辑不起作用答案

【问题标题】：Time comparison logic in Postgresql not workingPostgresql中的时间比较逻辑不起作用
【发布时间】：2023-03-25 09:18:01
【问题描述】：

我已经为 postgresql 编写代码大约两个星期了，这是我第一次在（真正的）数据库中玩，从 2003 年的访问（哦，不）交换，这太限制了，处理数据很慢.

我编写了一个函数，它可以查看另一个数据库中的日志，以了解为客户提供服务所需的时间。问题是，如果 3 分钟内数据库中没有任何操作，我正试图让它 stop 看起来并表现得好像服务结束了。有一笔交易是硬停止的，我用“E”标记它，如果用户名不同，则服务已经结束。对于硬停止和用户名更改，代码可以正常工作。对于时间逻辑，它没有。

CREATE FUNCTION rspcalc() RETURNS VOID
language plpgsql as $$
<<fn>>
DECLARE

_reportdata public.transactional_flag%ROWTYPE;
_currentusername varchar(255);
_intransaction boolean;
_nextslice time;
_endtime timestamp;
_currenttime timestamp;

BEGIN

_currentusername = 'XXXX';
_intransaction = false;

FOR _reportdata IN
    SELECT * FROM transactional_flag
        ORDER BY transactional_username, transactional_actiontime DESC LOOP

    --If username currently in use is not the username on the row, end the transaction measure

    IF NOT (_currentusername = _reportdata.transactional_username) THEN

        IF _intransaction THEN
        INSERT INTO transactional_report (transactional_endtime, transactional_starttime, transactional_username) 
            VALUES (_endtime, _currenttime, _currentusername);
        END IF;

        _intransaction = FALSE;
        _currentusername = _reportdata.transactional_username;
        _nextslice = '00:00:00'::time;

    END IF;

    CASE _reportdata.transactional_type

    --O represents an output - the assumption is if they do happen, they happen within 5 secounds of the end of a transaction

        WHEN 'O' THEN

            IF _intransaction THEN

                IF _reportdata.transactional_actiontime > (_currenttime + _nextslice) THEN

                INSERT INTO transactional_report (transactional_endtime, transactional_starttime, transactional_username) 
                    VALUES (_endtime, _currenttime, _currentusername);

                _intransaction = FALSE;
                _nextslice = '00:00:05'::time;
                ELSE

                _currenttime = _reportdata.transactional_actiontime;
                _nextslice = '00:03:00'::time;

                END IF;

            ELSE

                _currenttime = _reportdata.transactional_actiontime;
                _endtime = _reportdata.transactional_actiontime;
                _nextslice = '00:00:05'::time;

            END IF;

    --E represents the end of a transaction

        WHEN 'E' THEN

            IF _intransaction THEN

                INSERT INTO transactional_report (transactional_endtime, transactional_starttime, transactional_username) 
                    VALUES (_endtime, _currenttime, _currentusername);

                _intransaction = true;
                _endtime = _reportdata.transactional_actiontime;
                _currenttime = _reportdata.transactional_actiontime;
                _nextslice = '00:03:00'::time;

            ELSE

                IF _reportdata.transactional_actiontime > (_currenttime + _nextslice) THEN

                _endtime = _reportdata.transactional_actiontime;

                END IF;

            _currenttime = _reportdata.transactional_actiontime;
            _nextslice = '00:03:00'::time;
            _intransaction = true;

            END IF;

    --N represents any user use of the system, except an end
    --S represents a document creation

        WHEN 'N', 'S' THEN

            IF _intransaction THEN

                IF _reportdata.transactional_actiontime > (_currenttime + _nextslice) THEN

                INSERT INTO transactional_report (transactional_endtime, transactional_starttime, transactional_username) 
                    VALUES (_endtime, _currenttime, _currentusername);

                _intransaction = FALSE;
                _nextslice = '00:00:00'::time;

                ELSE
                _currenttime = _reportdata.transactional_actiontime;
                _nextslice = '00:03:00'::time;
                END IF;

            ELSE

            _nextslice = '00:00:00'::time;

            END IF;

        ELSE
        --PANIC

    END CASE;

END LOOP;

END $$;

我的 RTFM 太难了（但可能还不够难）。我已经逐段测试了大部分代码，但我处于松散的结局。

我最近才自学用 VB6 编写代码，因此您可以就代码的任何方面提供任何建议，我们将不胜感激！

CREATE TABLE transactional_flag
(
  transactional_rowid bigserial NOT NULL,
  transactional_actiontime timestamp without time zone,
  transactional_systemstring character varying(3),
  transactional_username character varying(255),
  transactional_type character varying(1),
  CONSTRAINT transactional_flag_pkey PRIMARY KEY (transactional_rowid)
)
WITH (
  OIDS=FALSE
);

CREATE INDEX transactional_index
  ON transactional_flag
  USING btree
  (transactional_username COLLATE pg_catalog."default", transactional_actiontime DESC);

CREATE TABLE transactional_report
(
  transactional_rowid bigserial NOT NULL,
  transactional_endtime timestamp without time zone,
  transactional_starttime timestamp without time zone,
  transactional_username character varying(255),
  CONSTRAINT transactional_report_pkey PRIMARY KEY (transactional_rowid)
)
WITH (
  OIDS=FALSE
);


INSERT INTO transactional_report
    ("transactional_rowid", "transactional_endtime", "transactional_starttime", "transactional_username")
VALUES
    (1004053,'2014-09-19 01:21:09','2014-09-15 01:06:07','EXSP1049'),
    (1004054,'2014-09-15 01:06:06','2014-09-12 06:30:49','EXSP1049')
;

INSERT INTO transactional_flag
    ("transactional_rowid", "transactional_actiontime", "transactional_systemstring", "transactional_username", "transactional_type")
VALUES
    (16543226, '2014-09-19 01:21:22', 'PEA', 'EXSP1049', 'N'),
    (16543163, '2014-09-19 01:21:10', 'PEA', 'EXSP1049', 'N'),
    (16543153, '2014-09-19 01:21:09', 'PEA', 'EXSP1049', 'N'),
    (16820614, '2014-09-19 01:21:09', 'PEA', 'EXSP1049', 'E'),
    (16543135, '2014-09-19 01:21:03', 'PEA', 'EXSP1049', 'N'),
(16543012, '2014-09-19 01:20:36', 'PEA', 'EXSP1049', 'N'),
(16543007, '2014-09-19 01:20:35', 'PEA', 'EXSP1049', 'N'),
(16542996, '2014-09-19 01:20:34', 'PEA', 'EXSP1049', 'N'),
(16542997, '2014-09-19 01:20:34', 'PEA', 'EXSP1049', 'N'),
(16542908, '2014-09-19 01:20:09', 'PEA', 'EXSP1049', 'N'),
(16542864, '2014-09-19 01:19:58', 'PEA', 'EXSP1049', 'N'),
(16542858, '2014-09-19 01:19:56', 'PEA', 'EXSP1049', 'N'),
(16542852, '2014-09-19 01:19:54', 'PEA', 'EXSP1049', 'N'),
(16542693, '2014-09-19 01:19:17', 'PEA', 'EXSP1049', 'N'),
(16542605, '2014-09-19 01:18:53', 'PEA', 'EXSP1049', 'N'),
(16542600, '2014-09-19 01:18:52', 'PEA', 'EXSP1049', 'N'),
(16542498, '2014-09-19 01:18:24', 'PEA', 'EXSP1049', 'N'),
(16542494, '2014-09-19 01:18:22', 'PEA', 'EXSP1049', 'N'),
(16542424, '2014-09-19 01:18:13', 'PEA', 'EXSP1049', 'N'),
(16542183, '2014-09-19 01:17:43', 'PEA', 'EXSP1049', 'N'),
(15903153, '2014-09-15 01:06:07', 'PEA', 'EXSP1049', 'N'),
(15903146, '2014-09-15 01:06:06', 'PEA', 'EXSP1049', 'N'),
(16797265, '2014-09-15 01:06:06', 'PEA', 'EXSP1049', 'E'),
(15903060, '2014-09-15 01:05:48', 'PEA', 'EXSP1049', 'N'),
(15903046, '2014-09-15 01:05:45', 'PEA', 'EXSP1049', 'N'),
(15902188, '2014-09-15 01:03:18', 'PEA', 'EXSP1049', 'N'),
(15902173, '2014-09-15 01:03:14', 'PEA', 'EXSP1049', 'N'),
(15900149, '2014-09-15 00:57:18', 'PEA', 'EXSP1049', 'N'),
(15899930, '2014-09-15 00:56:36', 'PEA', 'EXSP1049', 'N'),
(15899922, '2014-09-15 00:56:34', 'PEA', 'EXSP1049', 'N'),
(15899430, '2014-09-15 00:54:55', 'PEA', 'EXSP1049', 'N'),
(15899406, '2014-09-15 00:54:51', 'PEA', 'EXSP1049', 'N'),
(15899053, '2014-09-15 00:53:16', 'PEA', 'EXSP1049', 'N'),
(15899042, '2014-09-15 00:53:12', 'PEA', 'EXSP1049', 'N'),
(15898854, '2014-09-15 00:52:17', 'PEA', 'EXSP1049', 'N'),
(15898698, '2014-09-15 00:51:32', 'PEA', 'EXSP1049', 'N'),
(15898683, '2014-09-15 00:51:29', 'PEA', 'EXSP1049', 'N'),
(15898682, '2014-09-15 00:51:28', 'PEA', 'EXSP1049', 'N'),
(15898645, '2014-09-15 00:51:21', 'PEA', 'EXSP1049', 'N'),
(15898637, '2014-09-15 00:51:19', 'PEA', 'EXSP1049', 'N'),
(15898605, '2014-09-15 00:51:11', 'PEA', 'EXSP1049', 'N'),
(15898046, '2014-09-15 00:49:23', 'PEA', 'EXSP1049', 'N'),
(15897966, '2014-09-15 00:49:10', 'PEA', 'EXSP1049', 'N'),
(15897916, '2014-09-15 00:49:00', 'PEA', 'EXSP1049', 'N'),
(15897894, '2014-09-15 00:48:54', 'PEA', 'EXSP1049', 'N'),
(15897620, '2014-09-15 00:48:02', 'PEA', 'EXSP1049', 'N'),
(15897556, '2014-09-15 00:47:49', 'PEA', 'EXSP1049', 'N'),
(15897528, '2014-09-15 00:47:44', 'PEA', 'EXSP1049', 'N'),
(15897324, '2014-09-15 00:47:00', 'PEA', 'EXSP1049', 'N'),
(15897300, '2014-09-15 00:46:55', 'PEA', 'EXSP1049', 'N'),
(15892174, '2014-09-15 00:28:37', 'PEA', 'EXSP1049', 'N'),
(15886571, '2014-09-15 00:10:07', 'PEA', 'EXSP1049', 'N'),
(15886455, '2014-09-15 00:09:47', 'PEA', 'EXSP1049', 'N'),
(15886286, '2014-09-15 00:09:22', 'PEA', 'EXSP1049', 'N'),
(15859397, '2014-09-12 06:30:49', 'PEA', 'EXSP1049', 'N'),
(16795869, '2014-09-12 06:30:49', 'PEA', 'EXSP1049', 'E'),
(15859389, '2014-09-12 06:30:48', 'PEA', 'EXSP1049', 'N'),
(15859375, '2014-09-12 06:30:46', 'PEA', 'EXSP1049', 'N'),
(15859247, '2014-09-12 06:30:18', 'PEA', 'EXSP1049', 'N'),
(15859228, '2014-09-12 06:30:15', 'PEA', 'EXSP1049', 'N')
;

【问题讨论】：

我认为您可能需要显示与代码相对应的实际数据，否则很难说出发生了什么。你能展示一些样本数据吗？ sqlfiddle.com 。我也不太明白你想通过这里的无效程序来达到什么目的。
我没有 OpenID，所以我只是在这里添加了架构。两个 transactional_endtime 都是正确的，但开始时间应该分别是 2014-09-19 01:17:43 和 2014-09-15 01:03:14。
老实说，我不知道为什么我选择了无效程序。我这样做是因为它允许我执行代码。我对还有哪些其他选择不太自信或了解。

标签： postgresql timestamp comparison plpgsql

【解决方案1】：

不确定为什么会这样，但我重组了代码并将 _nextslice 的类型更改为时间戳。我还围绕销售订单添加了更多功能。

CREATE FUNCTION rspcalc() RETURNS VOID 
language plpgsql as $$
<<fn>>
DECLARE

_reportdata public.transactional_flag%ROWTYPE;
_currentusername varchar(255);
_currentSOtype varchar(4);
_intransaction boolean;
_nextslice timestamp;
_endtime timestamp;
_currenttime timestamp;

BEGIN

_currentusername = 'XXXX';
_intransaction = false;
_currentSOtype = '';

FOR _reportdata IN
    SELECT * FROM transactional_flag
        ORDER BY transactional_username, transactional_actiontime DESC LOOP

    --If username currently in use is not the username on the row, end the transaction measure

    IF NOT (_currentusername = _reportdata.transactional_username) THEN

        IF _intransaction THEN
        INSERT INTO transactional_report (transactional_endtime, transactional_starttime, transactional_username, transactional_salesordertype) 
            VALUES (_endtime, _currenttime, _currentusername, _currentSOtype);
        END IF;

        _intransaction = FALSE;
        _currentusername = _reportdata.transactional_username;
        _endtime = _reportdata.transactional_actiontime;
        _currentSOtype = '';

    END IF;

    --If this row's actiontime is before the acceptable backwards-stretching _nextslice, end the transaction

    IF _intransaction AND (_reportdata.transactional_actiontime < _nextslice) THEN

    INSERT INTO transactional_report (transactional_endtime, transactional_starttime, transactional_username, transactional_salesordertype) 
        VALUES (_endtime, _currenttime, _currentusername, _currentSOtype);

    _intransaction = FALSE;
    _currentSOtype = '';

    END IF;

    CASE _reportdata.transactional_type

    --N represents any CIC0 or VA01 transaction in STAD

        WHEN 'N' THEN

            IF _intransaction THEN

            _nextslice = _reportdata.transactional_actiontime - '00:03:00'::time;

            ELSE

            _nextslice = _reportdata.transactional_actiontime;

            END IF;
    --S represents a document creation in VBAK

        WHEN 'S' THEN

            IF _intransaction THEN

            _nextslice = _reportdata.transactional_actiontime - '00:03:00'::time;
            _currentSOtype = _reportdata.transactional_salesordertype;

            ELSE

            _nextslice = _reportdata.transactional_actiontime;

            END IF;

    --O represents an output in NAST

        WHEN 'O' THEN

            IF _intransaction THEN

            _nextslice = _reportdata.transactional_actiontime - '00:03:00'::time;

            ELSE

            _nextslice = _reportdata.transactional_actiontime - '00:00:05'::time;
            _endtime = _reportdata.transactional_actiontime;

            END IF;

    --E represents a VA - U - 3000 in STAD - the end of a transaction

        WHEN 'E' THEN

            IF _intransaction THEN

                INSERT INTO transactional_report (transactional_endtime, transactional_starttime, transactional_username, transactional_salesordertype) 
                    VALUES (_endtime, _currenttime, _currentusername, _currentSOtype);

                _currentSOtype = '';

                _endtime = _reportdata.transactional_actiontime;

            ELSE
                IF _endtime > (_reportdata.transactional_actiontime + '00:00:05'::time) THEN
                    _endtime = _reportdata.transactional_actiontime;
                END IF;

            END IF;

        _nextslice = _reportdata.transactional_actiontime - '00:03:00'::time;
        _intransaction = TRUE;

        ELSE
        --PANIC

    END CASE;

_currenttime = _reportdata.transactional_actiontime;

END LOOP;

END $$;

【讨论】：