์ธํŒŒ

You Can Become A

Pro

๋Šฆ๊ฒŒ ์‹œ์ž‘ํ•ด๋„ ๋ˆ„๊ตฌ๋“ ์ง€ ๋…ธ๋ ฅํ•˜๋ฉด ๊ฐœ๋ฐœ์ž๊ฐ€ ๋ ์ˆ˜ ์žˆ์–ด์š” !

์„œ๋ธŒ์ฟผ๋ฆฌ

๊ณต๋ถ€ํ•œ ๋‚ด์šฉ์„ ์ •๋ฆฌํ•ฉ๋‹ˆ๋‹ค
MySQL

[MYSQL] ๐Ÿ“š ์„œ๋ธŒ์ฟผ๋ฆฌ ๊ฐœ๋… & ๋ฌธ๋ฒ• ๐Ÿ’ฏ ์ •๋ฆฌ

์„œ๋ธŒ์ฟผ๋ฆฌ(Subquery) ์„œ๋ธŒ์ฟผ๋ฆฌ(subquery)๋ž€ ๋‹ค๋ฅธ ์ฟผ๋ฆฌ ๋‚ด๋ถ€์— ํฌํ•จ๋˜์–ด ์žˆ๋Š” SELETE ๋ฌธ์„ ์˜๋ฏธํ•œ๋‹ค. ์„œ๋ธŒ์ฟผ๋ฆฌ๋ฅผ ํฌํ•จํ•˜๊ณ  ์žˆ๋Š” ์ฟผ๋ฆฌ๋ฅผ ์™ธ๋ถ€์ฟผ๋ฆฌ(outer query)๋ผ๊ณ  ๋ถ€๋ฅด๋ฉฐ, ์„œ๋ธŒ์ฟผ๋ฆฌ๋Š” ๋‚ด๋ถ€์ฟผ๋ฆฌ(inner query)๋ผ๊ณ ๋„ ๋ถ€๋ฅธ๋‹ค. ์„œ๋ธŒ์ฟผ๋ฆฌ๋Š” ๋‹ค์Œ๊ณผ ๊ฐ™์ด ๊ด„ํ˜ธ() ๋กœ ๊ฐ์‹ธ์ ธ์„œ ํ‘œํ˜„ ๋œ๋‹ค. [ ์„œ๋ธŒ ์ฟผ๋ฆฌ ์‹คํ–‰ ์ˆœ์„œ ] ์„œ๋ธŒ์ฟผ๋ฆฌ ์‹คํ–‰ โ†’ ๋ฉ”์ธ(๋ถ€๋ชจ) ์ฟผ๋ฆฌ ์‹คํ–‰ ์„œ๋ธŒ์ฟผ๋ฆฌ๋Š” ํ•˜๋‚˜์˜ SQL ๋ฌธ ์•ˆ์— ํฌํ•จ๋˜์–ด ์žˆ๋Š” ๋˜ ๋‹ค๋ฅธ SQL๋ฌธ์„ ๋งํ•œ๋‹ค. (select * from table) ๊ฐ™์ด ๊ด„ํ˜ธ()์•ˆ์— ์žˆ๋Š” ์ฟผ๋ฆฌ๋ฅผ ์„œ๋ธŒ ์ฟผ๋ฆฌ๋ผ ๋งํ•œ๋‹ค ์„œ๋ธŒ์ฟผ๋ฆฌ(=์ž์‹์ฟผ๋ฆฌ, ๋‚ด๋ถ€์ฟผ๋ฆฌ) - ๋ฉ”์ธ์ฟผ๋ฆฌ ์ปฌ๋Ÿผ ์‚ฌ์šฉ ๊ฐ€๋Šฅ ๋ฉ”์ธ์ฟผ๋ฆฌ(=๋ถ€๋ชจ์ฟผ๋ฆฌ, ์™ธ๋ถ€์ฟผ๋ฆฌ) - ์„œ๋ธŒ์ฟผ๋ฆฌ ์ปฌ๋Ÿผ ์‚ฌ์šฉ ๋ถˆ๊ฐ€ * Java ๊ฐ์ œ์ง€ํ–ฅ์˜ ์ƒ์†๊ณผ ๋˜‘๊ฐ™์€ ๊ฐœ๋…์ด๋‹ค...

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์ธํŒŒ_
2022.06.05
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