Diréktori Tulisan
database MySQLUni urutan ku query sintaksis / pamakéan pernyataan
MySQL operator UNION
Tutorial ieu ngenalkeun anjeun kana sintaksis sareng conto operator MySQL UNION.
katerangan
Operator MySQL UNION dipaké pikeun ngagabungkeun hasil dua atawa leuwih pernyataan SELECT kana hiji set hasil tunggal.Sababaraha pernyataan SELECT miceun duplikat data.
tata basa
Format sintaksis operator MySQL UNION:
SELECT expression1, expression2, ... expression_n FROM tables [WHERE conditions] UNION [ALL | DISTINCT] SELECT expression1, expression2, ... expression_n FROM tables [WHERE conditions];
parameter
- babasan1, babasan2, ... babasan_n: Kolom pikeun dipulut.
- tabél: Tabél data pikeun dipulut.
- Syarat mana: Pilihan, kriteria pilarian.
- Béda: Optionally, piceun duplikat data tina set hasil.Operator UNION gaduh data deduplicated sacara standar, ku kituna modifier DISTINCT teu aya pangaruhna kana hasilna.
- KABEH: Opsional, mulihkeun sadaya set hasil, kalebet duplikat.
database demo
Dina tutorial ieu, urang bakal ngagunakeun database sampel chenweiliang.
Ieu data tina tabel "Situs Web":
mysql> SELECT * FROM Websites; +----+--------------+---------------------------+-------+---------+ | id | name | url | alexa | country | +----+--------------+---------------------------+-------+---------+ | 1 | Google | https://www.google.cm/ | 1 | USA | | 2 | 淘宝 | https://www.taobao.com/ | 13 | CN | | 3 | 陈沩亮博客 | http://www.chenweiliang.com/ | 4689 | CN | | 4 | 微博 | http://weibo.com/ | 20 | CN | | 5 | Facebook | https://www.facebook.com/ | 3 | USA | | 7 | stackoverflow | http://stackoverflow.com/ | 0 | IND | +----+---------------+---------------------------+-------+---------+
Ieu data kanggo "aplikasi" APP:
mysql> SELECT * FROM apps; +----+------------+-------------------------+---------+ | id | app_name | url | country | +----+------------+-------------------------+---------+ | 1 | QQ APP | http://im.qq.com/ | CN | | 2 | 微博 APP | http://weibo.com/ | CN | | 3 | 淘宝 APP | https://www.taobao.com/ | CN | +----+------------+-------------------------+---------+ 3 rows in set (0.00 sec)
SQL UNION conto
Pernyataan SQL di handap ieu milih sadayana tina tabel "Situs Web" sareng "aplikasi".bédanagara (ngan nilai béda):
Contona
SELECT country FROM Websites UNION SELECT country FROM apps ORDER BY country;
SQL UNION ALL conto
Pernyataan SQL di handap ieu nganggo UNION ALL pikeun milih tina tabel "Situs Web" sareng "aplikasi".sadayananagara (ogé gaduh nilai duplikat):
Contona
SELECT country FROM Websites UNION ALL SELECT country FROM apps ORDER BY country;
SQL UNION ALL kalawan WHERE
Pernyataan SQL di handap ieu nganggo UNION ALL pikeun milih tina tabel "Situs Web" sareng "aplikasi".sadayanaData pikeun Cina (CN) (ogé sareng nilai duplikat):
Contona
SELECT country, name FROM Websites WHERE country='CN' UNION ALL SELECT country, app_name FROM apps WHERE country='CN' ORDER BY country;
Blog Hope Chen Weiliang ( https://www.chenweiliang.com/ ) ngabagi "urutan union ku sintaksis query / pamakean pernyataan dina database MySQL", anu ngabantosan anjeun.
Wilujeng ngabagikeun tautan artikel ieu:https://www.chenweiliang.com/cwl-475.html
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