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SQL์ฝ”ํ…Œ1

[ํ”„๋กœ๊ทธ๋ž˜๋จธ์Šค ์ฝ”๋”ฉํ…Œ์ŠคํŠธ] SQL Lv.1 ๋ฌธ์ œ ํ’€์ด ๋ชจ์Œ Level 1. SELECT์กฐ๊ฑด์— ๋งž๋Š” ํšŒ์›์ˆ˜ ๊ตฌํ•˜๊ธฐ  ๋ฌธ์ œ USER_INFO ํ…Œ์ด๋ธ”์—์„œ 2021๋…„์— ๊ฐ€์ž…ํ•œ ํšŒ์› ์ค‘ ๋‚˜์ด๊ฐ€ 20์„ธ ์ด์ƒ 29์„ธ ์ดํ•˜์ธ ํšŒ์›์ด ๋ช‡ ๋ช…์ธ์ง€ ์ถœ๋ ฅํ•˜๋Š” SQL๋ฌธ์„ ์ž‘์„ฑํ•ด์ฃผ์„ธ์š”. ํ’€์ด๋”๋ณด๊ธฐ1. ORACLE 1) TO_CHAR ์‚ฌ์šฉSELECT COUNT(*) AS USERS FROM USER_INFO WHERE TO_CHAR(JOINED, 'YYYY') = '2021' AND AGE BETWEEN 20 AND 29;  2) EXTRACT ์‚ฌ์šฉSELECT COUNT(*) AS USERS FROM USER_INFO WHERE EXTRACT(YEAR FROM JOINED) = 2021 AND AGE BETWEEN 20 AND 29;  3) ๋‚ ์งœ ๋ฒ”์œ„ ๋น„๊ตSELECT COUNT.. 2024. 8. 12.
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