2

問題

私は学校のコンテンツ管理システムに取り組んでおり、複数の結合されたテーブルのビューを作成できるようにしたいと考えています。テーブルを結合するだけでなく、各テーブルから複数の行を取得してビューの列として使用するには、PIVOT または GROUP_CONCAT (またはその他の関数) を実行する必要があります。視覚化を助けるために、私が取り組んでいるものを単純化したものを次に示します。

設定

構造：

DROP TABLE IF EXISTS `date`;
CREATE TABLE `date` (
  `col_pkid` int(11) NOT NULL AUTO_INCREMENT,
  `col_guid` varchar(100) NOT NULL DEFAULT '',
  `col_entry` varchar(100) NOT NULL,
  `col_inquiry_name` varchar(100) NOT NULL,
  `col_value` int(11) DEFAULT NULL,
  PRIMARY KEY (`col_pkid`)
);

DROP TABLE IF EXISTS `bigText`;
CREATE TABLE `bigText` (
  `col_pkid` int(11) NOT NULL AUTO_INCREMENT,
  `col_guid` varchar(100) NOT NULL DEFAULT '',
  `col_entry` varchar(100) NOT NULL,
  `col_inquiry_name` varchar(100) NOT NULL,
  `col_value` text,
  PRIMARY KEY (`col_pkid`)
);

DROP TABLE IF EXISTS `smallText`;
CREATE TABLE `smallText` (
  `col_pkid` int(11) NOT NULL AUTO_INCREMENT,
  `col_guid` varchar(100) NOT NULL,
  `col_entry` varchar(100) NOT NULL,
  `col_inquiry_name` varchar(100) NOT NULL,
  `col_value` varchar(100) DEFAULT '',
  PRIMARY KEY (`col_pkid`)
);

データ：

INSERT INTO `date` (`col_pkid`, `col_guid`, `col_entry`, `col_inquiry_name`, `col_value`)
VALUES
    (1,'d2kih1ho5z','1','Semester',1294834220),
    (2,'d2kih1j99y','2','Semester',1327077210);

INSERT INTO `bigText` (`col_pkid`, `col_guid`, `col_entry`, `col_inquiry_name`, `col_value`)
VALUES
    (16,'d2kih1kxwh','1','Description','Lorem ipsum dolor sit amet...'),
    (17,'d2kih1mhnn','2','Description','Consectetur adipiscing elit...');

INSERT INTO `smallText` (`col_pkid`, `col_guid`, `col_entry`, `col_inquiry_name`, `col_value`)
VALUES
    (1,'d2kih1njuj','1','Title','Addition and Subtraction'),
    (2,'d2kih1ot0x','1','Course','Math'),
    (16,'d2kj5osy71','1','Location','Building 7'),
    (17,'d2kj5p0z8f','1','Teachers','John'),
    (18,'d2kj5p5efi','1','Teachers','Jane'),
    (19,'d2kj5p98xv','1','Teachers',''),
    (20,'d2kj5pasi9','1','Teachers',''),
    (21,'d2kj5pbqbg','1','Teachers',''),
    (22,'d2kj5pdxdb','2','Title','Reading Mark Twain'),
    (23,'d2kih198do','2','Course','Literature'),
    (24,'d2kj5opcgo','2','Location','Building 4'),
    (25,'d2hd00n5eb','2','Teachers','Billy'),
    (26,'d2hea3jo74','2','Teachers','Bob'),
    (27,'d2hec78m5e','2','Teachers',''),
    (28,'d2hec7bnar','2','Teachers',''),
    (29,'d2hec7cbrq','2','Teachers','');

いくつかの失敗した試み

次のようにすることで、テーブルを適切に結合することができます。

DROP VIEW IF EXISTS entries;
CREATE VIEW entries AS
SELECT
    st.col_entry,
    if(st.col_inquiry_name = 'Title', st.col_value, NULL) AS 'Title', 
    if(st.col_inquiry_name = 'Course', st.col_value, NULL) AS 'Course',
    if(bt.col_inquiry_name = 'Description', bt.col_value, NULL) AS 'Description',
    if(d.col_inquiry_name = 'Semester', d.col_value, NULL) AS 'Semester',
    if(st.col_inquiry_name = 'Location', st.col_value, NULL) AS 'Location',
    if(st.col_inquiry_name = 'Teachers', st.col_value, NULL) AS 'Teachers'
FROM smallText st
INNER JOIN bigText bt
ON st.col_entry = bt.col_entry
INNER JOIN date d
ON bt.col_entry = d.col_entry
GROUP BY col_entry;

しかし、ここでは、各テーブルから最初の行の値のみを取得しています。これが、導入を試みた理由ですがGROUP_CONCAT、それもあまり成功していません。

DROP VIEW IF EXISTS entries;
CREATE VIEW entries AS
SELECT
    st.col_entry,
    GROUP_CONCAT(if(st.col_inquiry_name = 'Title', st.col_value, NULL)) AS 'Title', 
    GROUP_CONCAT(if(st.col_inquiry_name = 'Course', st.col_value, NULL)) AS 'Course',
    GROUP_CONCAT(if(bt.col_inquiry_name = 'Description', bt.col_value, NULL)) AS 'Description',
    GROUP_CONCAT(if(d.col_inquiry_name = 'Semester', d.col_value, NULL)) AS 'Semester',
    GROUP_CONCAT(if(st.col_inquiry_name = 'Location', st.col_value, NULL)) AS 'Location',
    GROUP_CONCAT(if(st.col_inquiry_name = 'Teachers', st.col_value, NULL)) AS 'Teachers'
FROM smallText st
INNER JOIN bigText bt
ON st.col_entry = bt.col_entry
INNER JOIN date d
ON bt.col_entry = d.col_entry
GROUP BY col_entry;

ビューの各列にテーブルの対応する値を入力することはできますが、結合された元の行数 (7 回) に従って、日付列と bigText 列が複製されています。

(また、別の追加レベルの複雑さとして...さまざまな教師が独自の列にも道を見つけるようにしたいと思います: Teacher_01、Teacher_02、.. Teacher_05、そして私はおそらくこれを推測します私が持っているものを大幅に再構築する必要があります。)

ありがとう！

...アップデート

FROMそのため、探しているものに少し近いものを出力するクエリを作成できましたが、句にサブクエリがあるため、ビューで使用できません。

SELECT
st.col_entry,
Title,
Course,
Description,
Semester,
Location,
Teachers
FROM smallText st
JOIN (SELECT smallText.col_entry, GROUP_CONCAT(if(smallText.col_inquiry_name = 'Title', smallText.col_value, NULL)) AS 'Title' 
    FROM smallText GROUP BY smallText.col_entry) a
ON a.col_entry = st.col_entry
JOIN (SELECT smallText.col_entry, GROUP_CONCAT(if(smallText.col_inquiry_name = 'Course', smallText.col_value, NULL)) AS 'Course'
    FROM smallText GROUP BY smallText.col_entry) b
ON b.col_entry = st.col_entry
JOIN (SELECT bigText.col_entry, GROUP_CONCAT(if(bigText.col_inquiry_name = 'Description', bigText.col_value, NULL)) AS 'Description'
    FROM bigText GROUP BY bigText.col_entry) c
ON c.col_entry = st.col_entry
JOIN (SELECT date.col_entry, GROUP_CONCAT(if(date.col_inquiry_name = 'Semester', date.col_value, NULL)) AS 'Semester'
    FROM date GROUP BY date.col_entry) d
ON d.col_entry = st.col_entry
JOIN (SELECT smallText.col_entry, GROUP_CONCAT(if(smallText.col_inquiry_name = 'Location', smallText.col_value, NULL)) AS 'Location'
    FROM smallText GROUP BY smallText.col_entry) e
ON e.col_entry = st.col_entry
JOIN (SELECT smallText.col_entry, GROUP_CONCAT(if(smallText.col_inquiry_name = 'Teachers', smallText.col_value, NULL)) AS 'Teachers'
    FROM smallText GROUP BY smallText.col_entry) f
ON f.col_entry = st.col_entry
GROUP BY st.col_entry

結果

このクエリの出力は次のようになります。

Entry   Title                           Course      Description                     Semester    Location    Teachers
---------------------------------------------------------------------------------------------------------------------------------
1       Addition and Subtraction        Math        Lorem ipsum dolor sit amet...   1294834220  Building 7  NULL
2       Reading Mark Twain              Literature  Consectetur adipiscing elit...  1327077210  Building 4  NULL

null 列を除いて、これTeachersは基本的に私が探しているものです (ただし、ビューでクエリを使用できる何らかの方法で生成されます)。

inquiry_nameさらに、上で述べたように、同じ値の複数の値を個々の列にプルできるようにしたいと考えています。したがって、最終的に必要な出力は次のようになります。

望ましい結果

Entry   Title                           Course      Description                     Semester    Location    Teachers_01 Teachers_02 Teachers_03 Teachers_04 Teachers_05
---------------------------------------------------------------------------------------------------------------------------------
1       Addition and Subtraction        Math        Lorem ipsum dolor sit amet...   1294834220  Building 7  John        Jane        NULL        NULL        NULL
2       Reading Mark Twain              Literature  Consectetur adipiscing elit...  1327077210  Building 4  Billy       Bob         NULL        NULL        NULL

ありがとう！

4

1 に答える 1

2

これは、教師にPIVOTa を適用するモックです。rownum

select s.col_entry,
  max(case when s.col_inquiry_name = 'Title' then s.col_value end) AS 'Title',
  max(case when s.col_inquiry_name = 'Course' then s.col_value end) AS 'Course',
  max(case when b.col_inquiry_name = 'Description' then b.col_value end) AS 'Description',
  max(case when d.col_inquiry_name = 'Semester' then d.col_value end) AS 'Semester',
  max(case when s.col_inquiry_name = 'Location' then s.col_value end) AS 'Location',
  max(case when tch.grp = 'Teachers_01' then tch.col_value end) AS 'Teachers_01',
  max(case when tch.grp = 'Teachers_02' then tch.col_value end) AS 'Teachers_02',
  max(case when tch.grp = 'Teachers_03' then tch.col_value end) AS 'Teachers_03',
  max(case when tch.grp = 'Teachers_04' then tch.col_value end) AS 'Teachers_04',
  max(case when tch.grp = 'Teachers_05' then tch.col_value end) AS 'Teachers_05'
from smallText s
left join bigText b
  on s.col_entry = b.col_entry 
left join date d
  on b.col_entry = d.col_entry 
left join
(
  select col_entry, col_value, concat('Teachers_0', group_row_number) grp
  from
  (
    select col_entry, col_value,
      @num := if(@col_entry = `col_entry`, @num + 1, 1) as group_row_number,
      @col_entry := `col_entry` as dummy
    from smallText , (SELECT @rn:=0) r
    where col_inquiry_name = 'Teachers'
      and col_value != ''
  ) x
) tch
  on s.col_entry = tch.col_entry
group by s.col_entry;

デモで SQL Fiddle を参照してください

編集＃1、提供した追加フィールドに基づいて、変数col_orderを使用せずに教師を決定するために使用できます。rownum

select s.col_entry,
  max(case when s.col_inquiry_name = 'Title' then s.col_value end) AS 'Title',
  max(case when s.col_inquiry_name = 'Course' then s.col_value end) AS 'Course',
  max(case when b.col_inquiry_name = 'Description' then b.col_value end) AS 'Description',
  max(case when d.col_inquiry_name = 'Semester' then d.col_value end) AS 'Semester',
  max(case when s.col_inquiry_name = 'Location' then s.col_value end) AS 'Location',
  max(case when s.col_inquiry_name = 'Teachers'
        and s.col_order = 1 then s.col_value end) AS 'Teachers_01',
  max(case when s.col_inquiry_name = 'Teachers'
        and s.col_order = 2 then s.col_value end) AS 'Teachers_02',
  max(case when s.col_inquiry_name = 'Teachers'
        and s.col_order = 3 then s.col_value end) AS 'Teachers_03',
  max(case when s.col_inquiry_name = 'Teachers'
        and s.col_order = 4 then s.col_value end) AS 'Teachers_04',
  max(case when s.col_inquiry_name = 'Teachers'
        and s.col_order = 5 then s.col_value end) AS 'Teachers_05'
from smallText s
left join bigText b
  on s.col_entry = b.col_entry 
left join date d
  on b.col_entry = d.col_entry 
group by s.col_entry

SQL Fiddle with Demoを参照してください

于 2012-09-18T16:59:08.480 に答える