๐Ÿง  SQL์ด๋ž€? โ€” ๋ฐ์ดํ„ฐ์™€ ๋Œ€ํ™”ํ•˜๋Š” ์–ธ์–ด

๐Ÿ“Œ SQL์˜ ์ •์˜

**SQL(Structured Query Language)**์€ ๊ด€๊ณ„ํ˜• ๋ฐ์ดํ„ฐ๋ฒ ์ด์Šค(RDB)์—์„œ ๋ฐ์ดํ„ฐ๋ฅผ ์ƒ์„ฑํ•˜๊ณ  ์กฐ์ž‘ํ•˜๊ธฐ ์œ„ํ•ด ์‚ฌ์šฉํ•˜๋Š” ํ‘œ์ค€ ์–ธ์–ด์ž…๋‹ˆ๋‹ค.

๐Ÿ’ฌ ์‹ค์ƒํ™œ ๋น„์œ 

SQL์€ ๋งˆ์น˜ ๋„์„œ๊ด€ ์‚ฌ์„œ์—๊ฒŒ ํ•˜๋Š” ๋ช…๋ น๋ฌธ๊ณผ ๊ฐ™์Šต๋‹ˆ๋‹ค.

"OO ์ฑ…์„ ์ฐพ์•„์ค˜", "OO ์ฑ…์„ ์ƒˆ๋กœ ์ถ”๊ฐ€ํ•ด์ค˜", "์ด ์ฑ…์€ ์ˆ˜์ •ํ•ด์ค˜" ๋“ฑ, ์šฐ๋ฆฌ๊ฐ€ ๋งํ•˜๋ฉด ์‚ฌ์„œ(DBMS)๊ฐ€ ์ฒ˜๋ฆฌํ•ฉ๋‹ˆ๋‹ค.


โœจ SQL์˜ ํŠน์ง•

ํŠน์ง• ์„ค๋ช…
๐Ÿ“ ํ‘œ์ค€ํ™” ANSI, ISO ํ‘œ์ค€์œผ๋กœ ๋‹ค์–‘ํ•œ DBMS(MySQL, Oracle, PostgreSQL ๋“ฑ)์—์„œ ์‚ฌ์šฉ ๊ฐ€๋Šฅ
๐Ÿ“š ์ง๊ด€์  ๋ฌธ๋ฒ• ์˜์–ด ๋ฌธ์žฅ์ฒ˜๋Ÿผ ์ฝํžˆ๋Š” ๊ตฌ๋ฌธ (์˜ˆ: SELECT name FROM users)
๐Ÿš€ ๊ฐ•๋ ฅํ•œ ์ฒ˜๋ฆฌ ๋Šฅ๋ ฅ ์ˆ˜์ฒœ๋งŒ ๊ฑด์˜ ๋ฐ์ดํ„ฐ๋„ ๊ฒ€์ƒ‰, ์ง‘๊ณ„, ์ˆ˜์ • ๋“ฑ์„ ๋น ๋ฅด๊ฒŒ ์ˆ˜ํ–‰ ๊ฐ€๋Šฅ

๐Ÿ“‚ SQL ๋ช…๋ น์–ด ๋ถ„๋ฅ˜

๋ถ„๋ฅ˜ ์„ค๋ช… ๋Œ€ํ‘œ ๋ช…๋ น์–ด
DDL (๋ฐ์ดํ„ฐ ์ •์˜ ์–ธ์–ด) ๋ฐ์ดํ„ฐ๋ฒ ์ด์Šค ๊ตฌ์กฐ ์ •์˜ CREATE, ALTER, DROP
DML (๋ฐ์ดํ„ฐ ์กฐ์ž‘ ์–ธ์–ด) ๋ฐ์ดํ„ฐ๋ฅผ ์‚ฝ์ž…, ์กฐํšŒ, ์ˆ˜์ •, ์‚ญ์ œ SELECT, INSERT, UPDATE, DELETE
DCL (๋ฐ์ดํ„ฐ ์ œ์–ด ์–ธ์–ด) ์ ‘๊ทผ ๊ถŒํ•œ ๋ฐ ๋ณด์•ˆ ์„ค์ • GRANT, REVOKE
TCL (ํŠธ๋žœ์žญ์…˜ ์ œ์–ด ์–ธ์–ด) ํŠธ๋žœ์žญ์…˜์˜ ์‹คํ–‰/์ทจ์†Œ ๊ด€๋ฆฌ COMMIT, ROLLBACK, SAVEPOINT

๐Ÿ”Ž ์ž์ฃผ ์“ฐ๋Š” SELECT ๋ฌธ๋ฒ•

๐Ÿ“˜ SELECT ~ FROM ~

๋ฐ์ดํ„ฐ๋ฅผ ์กฐํšŒํ•˜๋Š” ๊ธฐ๋ณธ ๋ฌธ์žฅ์ž…๋‹ˆ๋‹ค.

SELECT ์ด๋ฆ„, ๋‚˜์ด FROM ์‚ฌ์šฉ์ž;

๐ŸŽฏ ์˜๋ฏธ: ์‚ฌ์šฉ์ž ํ…Œ์ด๋ธ”์—์„œ ์ด๋ฆ„๊ณผ ๋‚˜์ด๋ฅผ ๋ณด์—ฌ์ค˜.


๐Ÿงฎ WHERE ์ ˆ โ€” ์กฐ๊ฑด ํ•„ํ„ฐ๋ง