UNION ์ด๋?
์ฌ๋ฌ ๊ฐ์ sql๋ฌธ์ ํฉ์ณ ํ๋์ sql๋ฌธ์ผ๋ก ๋ง๋ค์ด์ฃผ๋ ๋ฐฉ๋ฒ
โ
UNION vs. UNION ALL
๊ณตํต์ |
์ฐจ์ด์ |
๋ ์ฟผ๋ฆฌ๋ฌธ์ ํ๋๋ก ํฉ์ณ์ค๋ค. |
UNION |
UNION ALL |
โป ์ปฌ๋ผ๋ช ์ด ๊ฐ์์ผํ๋ค. (๊ฐ์ง ์์ ๊ฒฝ์ฐ AS๋ฅผ ์ฌ์ฉํ์ฌ ๊ฐ๊ฒํด์ฃผ์ด์ผํจ)
โป ์ปฌ๋ผ๋ณ ๋ฐ์ดํฐ ํ์ ์ด ๊ฐ์์ผํ๋ค.
โ
์ฌ์ฉ๋ฒ
โปโป์ปฌ๋ผ๋ช ์ด ๊ฐ์ ๋
SELECT * FROM [ํ ์ด๋ธ1] UNION SELECT * FROM [ํ ์ด๋ธ2];
SELECT * FROM [ํ ์ด๋ธ1] UNION ALL SELECT * FROM [ํ ์ด๋ธ2];
โ
โปโป์ปฌ๋ผ๋ช ์ด ๊ฐ์ง ์์ ๋
SELECT [์ปฌ๋ผ๋ช 1] AS [๋ณ๋ช 1], [์ปฌ๋ผ๋ช 2] AS [๋ณ๋ช 2] FROM [ํ ์ด๋ธ1]
UNION
SELECT [์ปฌ๋ผ๋ช 1] AS [๋ณ๋ช 1], [์ปฌ๋ผ๋ช 2] AS [๋ณ๋ช 2] FROM [ํ ์ด๋ธ2];
โ
SELECT [์ปฌ๋ผ๋ช 1] AS [๋ณ๋ช 1], [์ปฌ๋ผ๋ช 2] AS [๋ณ๋ช 2] FROM [ํ ์ด๋ธ1]
UNION ALL
SELECT [์ปฌ๋ผ๋ช 1] AS [๋ณ๋ช 1], [์ปฌ๋ผ๋ช 2] AS [๋ณ๋ช 2] FROM [ํ ์ด๋ธ2];