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๊ณผ๋ชฉII SQL ๊ธฐ๋ณธ ๋ฐ ํ™œ์šฉ 2์žฅ - 5์ ˆ GROUP FUNCTION
SQLD 2021. 5. 25. 16:16

๋ฐ์ดํ„ฐ ๋ถ„์„ ํ•จ์ˆ˜ (AGGREGATE FUNCTIONS) - GROUP FUNCTION์˜ ํ•œ ๋ถ€๋ถ„์ด๋ฉฐ, GROUP AGGREGATE FUNCTION์ด๋ผ๊ณ ๋„ ๋ถ€๋ฅผ ์ˆ˜ ์žˆ๋‹ค. COUNT,SUM,AVG,MAX,MIN์™ธ ๊ฐ์ข… ์ง‘๊ณ„ ํ•จ์ˆ˜๋“ค์ด ํฌํ•จ๋˜์–ด ์žˆ๋‹ค. (GROUP FUNCTIONS) - ๊ทธ๋ฃนํ•จ์ˆ˜๋กœ๋Š” ์ง‘๊ณ„ ํ•จ์ˆ˜ ์ œ์™ธํ•˜๋ฉด, ROLLUPํ•จ์ˆ˜, CUBE ํ•จ์ˆ˜, GROUPING SETS ํ•จ์ˆ˜๊ฐ€ ์žˆ๋‹ค. - ROLLUP์€ GROUP BY์˜ ํ™•์žฅ๋œ ํ˜•ํƒœ๋กœ ๋ณ‘๋ ฌ๋กœ ์ˆ˜ํ–‰์ด ๊ฐ€๋Šฅ. (๊ณ„์ธต์  ๋ถ„๋ฅ˜๋ฅผ ํฌํ•จํ•˜๊ณ  ์žˆ๋Š” ๋ฐ์ดํ„ฐ ์ง‘๊ณ„์— ์ ํ•ฉ) - CUBE ๋Š” ๊ฒฐํ•ฉ๊ฐ€๋Šฅํ•œ ๋ชจ๋“  ๊ฐ’์— ๋Œ€ํ•˜์—ฌ ๋‹ค์ฐจ์›์ ์ธ ์ง‘๊ณ„๋ฅผ ์ƒ์„ฑํ•˜๊ฒŒ ๋˜๋ฏ€๋กœ ROLLUP์— ๋น„ํ•ด ๋‹ค์–‘ํ•œ ๋ฐ์ดํ„ฐ๋ฅผ ์–ป๋Š” ์žฅ์ ์ด ์žˆ์ง€๋งŒ, ์‹œ์Šคํ…œ์— ๋ถ€ํ•˜๋ฅผ ๋งŽ์ด ์ฃผ๋Š” ๋‹จ์ ์ด ์žˆ๋‹ค. - GROUPING ..