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DataBase/Programmers2

[ํ”„๋กœ๊ทธ๋ž˜๋จธ์Šค ์ฝ”๋”ฉํ…Œ์ŠคํŠธ] SQL Lv.2 ๋ฌธ์ œ ํ’€์ด ๋ชจ์Œ Level 2. GROUP BY๋™๋ช… ๋™๋ฌผ ์ˆ˜ ์ฐพ๊ธฐ  ๋ฌธ์ œ๋™๋ฌผ ๋ณดํ˜ธ์†Œ์— ๋“ค์–ด์˜จ ๋™๋ฌผ ์ด๋ฆ„ ์ค‘ ๋‘ ๋ฒˆ ์ด์ƒ ์“ฐ์ธ ์ด๋ฆ„๊ณผ ํ•ด๋‹น ์ด๋ฆ„์ด ์“ฐ์ธ ํšŸ์ˆ˜๋ฅผ ์กฐํšŒํ•˜๋Š” SQL๋ฌธ์„ ์ž‘์„ฑํ•ด์ฃผ์„ธ์š”. ์ด๋•Œ ๊ฒฐ๊ณผ๋Š” ์ด๋ฆ„์ด ์—†๋Š” ๋™๋ฌผ์€ ์ง‘๊ณ„์—์„œ ์ œ์™ธํ•˜๋ฉฐ, ๊ฒฐ๊ณผ๋Š” ์ด๋ฆ„ ์ˆœ์œผ๋กœ ์กฐํšŒํ•ด์ฃผ์„ธ์š”. ํ’€์ด๋”๋ณด๊ธฐ1. ORACLE, MYSQLSELECT NAME, COUNT(NAME) AS COUNT FROM ANIMAL_INS WHERE NAME IS NOT NULL GROUP BY NAMEHAVING COUNT(NAME) > 1 ORDER BY NAME;   Level 2. SUM, MAX, MIN๊ฐ€๊ฒฉ์ด ์ œ์ผ ๋น„์‹ผ ์‹ํ’ˆ์˜ ์ •๋ณด ์ถœ๋ ฅํ•˜๊ธฐ  ๋ฌธ์ œ FOOD_PRODUCT ํ…Œ์ด๋ธ”์—์„œ ๊ฐ€๊ฒฉ์ด ์ œ์ผ ๋น„์‹ผ ์‹ํ’ˆ์˜ ์‹ํ’ˆ ID, ์‹ํ’ˆ ์ด๋ฆ„, ์‹ํ’ˆ ์ฝ”๋“œ, ์‹ํ’ˆ.. 2024. 8. 14.
[ํ”„๋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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