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๋ชฉ๋กSQL ์ค‘๋ณต๊ฐ’ ์ œ์™ธ (1)

DATA101

[SQLite] DINTINCT: ์ค‘๋ณต์„ ์ œ์™ธํ•œ ๋ฐ์ดํ„ฐ ์ฐพ๊ธฐ!

์˜ค๋Š˜์€ DISTINCT๋ฅผ ํ™œ์šฉํ•˜์—ฌ ์นผ๋Ÿผ ๋‚ด ์ค‘๋ณต ๊ฐ’์„ ์ œ์™ธํ•˜์—ฌ ๋ฐ์ดํ„ฐ๋ฅผ ์ถœ๋ ฅํ•˜๋Š” ๋ฐฉ๋ฒ•์— ๋Œ€ํ•ด ๊ณต์œ ํ•ด ๋“œ๋ฆฝ๋‹ˆ๋‹ค. ๋ฐ”๋กœ ์‹œ์ž‘ํ•˜์ฃ ! ์ค‘๋ณต๊ฐ’ ํฌํ•จํ•œ ๊ฒฝ์šฐ SELECT playerID FROM People; ์•„๋ž˜์™€ ๊ฐ™์ด People์ด๋ผ๋Š” ํ…Œ์ด๋ธ”์— playerID ์นผ๋Ÿผ์—๋Š” MLB ์„ ์ˆ˜๋“ค์˜ ID๊ฐ€ ๋‹ด๊ฒจ์žˆ์Šต๋‹ˆ๋‹ค. SELECT COUNT(nameFirst || ' ' || nameLast) AS Cnt_All FROM People; People ํ…Œ์ด๋ธ”์— ๋‹ด๊ฒจ ์žˆ๋Š” ์„ ์ˆ˜๋Š” ์•„๋ž˜์™€ ๊ฐ™์ด 19,878๋ช…์ž…๋‹ˆ๋‹ค. DISTINCT: ์ค‘๋ณต๊ฐ’ ์ œ์™ธ SELECT COUNT(DISTINCT(nameFirst || ' ' || nameLast)) AS Cnt_unique FROM People; ๋™๋ช…์ด์ธ์ธ ํ”„๋กœ์„ ์ˆ˜๊ฐ€ ๋งŽ๋‹ค๋Š” ์ ์—์„œ ๊ฐ™์€ ์ด๋ฆ„..
AI & ๋น…๋ฐ์ดํ„ฐ/SQLite 2021. 2. 10. 09:20
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