[英]Merging sql rows with same values
我已經向數據庫中添加了一些數據,但我發現我有很多重復項,當然還有不同的鍵,我想將它們合並為一條記錄。
我想在sql數據庫本身中執行此操作,我不想截斷表並再次插入值(沒有重復項),因為腳本非常慢。
這是我的情況的一個示例:
表軌道:
key | artist | title
----|-----------|--------
k1 | artist1 | title1
----|-----------|--------
k2 | artist1 | title1
----|-----------|--------
k3 | artist1 | title1
表格圖表:
trackKey | otherKey | anotherKey | value
---------|----------|--------------|---------
k1 | ok1 | ak4 | v1
---------|----------|--------------|---------
k3 | ok2 | ak2 | v2
---------|----------|--------------|---------
k1 | ok3 | ak9 | v2
---------|----------|--------------|---------
k2 | ok4 | ak1 | v6
其中chart.trackKey
引用track.key
我想要實現的結果是:
表軌道:
key | artist | title
----|-----------|--------
k1 | artist1 | title1
表格圖表:
trackKey | otherKey | anotherKey | value
---------|----------|--------------|---------
k1 | ok1 | ak4 | v1
---------|----------|--------------|---------
k1 | ok2 | ak2 | v2
---------|----------|--------------|---------
k1 | ok3 | ak9 | v2
---------|----------|--------------|---------
k1 | ok4 | ak1 | v6
這樣, track
相同條目的每個重復項將合並為一行,並且chart
中的舊鍵將更新為track
表中唯一的舊鍵。
有什么辦法可以在SQL中做到這一點?
編輯:
基於@popovitsj的答案的解決方案#1
UPDATE chart c SET trackUri =
(WITH track_unique AS
(
SELECT MIN(uri) AS key, artist, title, album. artwork FROM track
GROUP BY artist, title
)
SELECT tu.key FROM chart c1
INNER JOIN track t ON c1.trackUri = t.key
INNER JOIN track_unique tu ON t.artist = tu.artist AND t.title = tu.title
WHERE c1.trackUri = c.trackUri and c1.countryId = c.countryId and c1.date = c.date);
回報
#1064 - Syntax error near
'track_unique AS (
SELECT MIN(uri) AS key, artist, title, album. artwork FR' line 2
基於@juergen d答案的解決方案#2
update chart
join track t1 on t1.uri = chart.trackUri
left join
(
select min(uri) as key
from track
group by artist, title
) tmp_track on tmp_track.key = chart.trackUri
set trackkey = tmp_tbl.key
where chart.trackUri not in
(
select min(uri)
from track
group by artist, title
having count(*) > 1
);
回報
#1064 - Syntax error near
'key
from track
group by artist, title
) tmp_track on tmp_track.key = c' line 5
我不知道自己在做什么錯,所以我要添加架構定義(取自phpMyAdmin )
第一個with子句獲取您要保留的ID,然后在下一個選擇查詢中,將這些ID與圖表ID進行匹配。
我根據您對原始答案的修改對這個答案進行了編輯。 該答案假定chart(countryid,date)
唯一地標識一個圖表,並且僅當track(key,artist,title,album)
相等時才可以合並track(key,artist,title,album)
。
UPDATE chart c SET trackUri =
(WITH track_unique AS
(
SELECT MIN(uri) AS key, artist, title, album, artwork FROM track
GROUP BY artist, title, album, artwork
)
SELECT tu.key FROM chart c1
INNER JOIN track t ON c1.trackUri = t.key
INNER JOIN track_unique tu
ON t.artist = tu.artist
AND t.title = tu.title
AND t.album = tu.album
AND t.artwork = tu.artwork
WHERE c1.trackUri = c.trackUri
AND c1.countryId = c.countryId
AND c1.date = c.date);
要在執行此更新后刪除剩余的重復項,請執行以下操作:
DELETE FROM track
WHERE uri NOT IN
(SELECT MIN(uri) AS key, artist, title, album, artwork
FROM track
GROUP BY artist, title, album, artwork);
如果重復的值是完全重復的,則可以使用
SELECT MIN(key),artist,title FROM track GROUP BY artist,title;
以獲得track
表中數據的無重復版本。 您可以將其放在一個臨時表中並交換它們,或者使用SQL客戶端下載數據並重新導入它,等等。為了安全起見,我不會在單個語句中嘗試全部操作。 。
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