Yilguk Seo ๐Ÿš€

Yilguk Seo ๐Ÿš€

AI Researcher

DevCourse2_SQL

SQL Analysis - ํŠธ๋žœ์žญ์…˜๊ณผ ๊ธฐํƒ€ ๊ณ ๊ธ‰ SQL ๋ฌธ๋ฒ•

10 minute read

์ˆ™์ œ1 ๋ฆฌ๋ทฐ ์‚ฌ์šฉ์ž๋ณ„๋กœ ์ฒ˜์Œ ์ฑ„๋„๊ณผ ๋งˆ์ง€๋ง‰ ์ฑ„๋„ ์•Œ์•„๋‚ด๊ธฐ ROW_NUMBER vs. FIRST_VALUE/LAST_VALUE ์‚ฌ์šฉ์ž 251๋ฒˆ์˜ ์‹œ๊ฐ„์ˆœ์œผ๋กœ ๋ดค์„ ๋•Œ ์ฒซ ๋ฒˆ์งธ ์ฑ„๋„๊ณผ ๋งˆ์ง€๋ง‰ ์ฑ„๋„์€ ๋ฌด์—‡์ธ๊ฐ€? ์•„๋ž˜ ์ฟผ๋ฆฌ๋ฅผ ์‹คํ–‰ํ•ด์„œ ์ฒ˜์Œ๊ณผ ๋งˆ์ง€๋ง‰ ์ฑ„๋„์„ ๋ณด๋ฉด ...

SQL Analysis - JOIN & ๋ฆฌ๋ทฐ

10 minute read

JOIN SQL ์กฐ์ธ์€ ๋‘ ๊ฐœ ํ˜น์€ ๊ทธ ์ด์ƒ์˜ ํ…Œ์ด๋ธ”๋“ค์„ ๊ณตํ†ต ํ•„๋“œ๋ฅผ ๊ฐ€์ง€๊ณ  MERGE ํ•˜๋Š”๋ฐ ์‚ฌ์šฉ๋จ. ์ด๋Š” ์Šคํƒ€ ์Šคํ‚ค๋งˆ๋กœ ๊ตฌ์„ฑ๋œ ํ…Œ์ด๋ธ”๋“ค๋กœ ๋ถ„์‚ฐ๋˜์–ด ์žˆ๋˜ ์ •๋ณด๋ฅผ ํ†ตํ•ฉํ•˜๋Š” ๋ฐ ์‚ฌ์šฉ. JOIN์˜ ๊ฒฐ๊ณผ๋Š” ๋ฐฉ์‹์— ์ƒ๊ด€์—†์ด ์–‘์ชฝ์˜ ํ•„๋“œ๋ฅผ ๋ชจ๋‘ ๊ฐ€์ง„ ์ƒˆ๋กœ์šด ํ…Œ์ด๋ธ”์„ ๋งŒ๋“ค์–ด๋‚ด๊ฒŒ ๋จ. ์กฐ...

SQL Analysis - GROUP BY & CTAS

4 minute read

GROUP BY์™€ AGGREGATE ํ•จ์ˆ˜ ํ…Œ์ด๋ธ”์˜ ๋ ˆ์ฝ”๋“œ๋ฅผ ๊ทธ๋ฃนํ•‘ํ•˜์—ฌ ๊ทธ๋ฃน๋ณ„๋กœ ๋‹ค์–‘ํ•œ ์ •๋ณด๋ฅผ ๊ณ„์‚ฐ ์ด๋Š” ๋‘ ๋‹จ๊ณ„๋กœ ์ด๋ฃจ์–ด์ง ๊ทธ๋ฃนํ•‘์„ ํ•  ํ•„๋“œ๋ฅผ ๊ฒฐ์ • (ํ•˜๋‚˜ ์ด์ƒ์˜ ํ•„๋“œ๊ฐ€ ๋  ์ˆ˜ ์žˆ์Œ) GROUP BY๋กœ ์ง€์ • (ํ•„๋“œ ์ด๋ฆ„...

SQL Analysis - SELECT

5 minute read

Redshift ๋ก ์น˜ ๋ฐ๋ชจ ์˜ˆ์ œ ํ…Œ์ด๋ธ” ์†Œ๊ฐœ ์‚ฌ์šฉ์ž ID: ์›น์„œ๋น„์Šค์—์„œ ๋“ฑ๋ก๋œ ์‚ฌ์šฉ์ž๋งˆ๋‹ค ๋ถ€์—ฌํ•˜๋Š” ์œ ์ผํ•œ ID ์„ธ์…˜ ID: ์„ธ์…˜๋งˆ๋‹ค ๋ถ€์—ฌ๋˜๋Š” ID ์„ธ์…˜: ์‚ฌ์šฉ์ž์˜ ๋ฐฉ๋ฌธ์„ ๋…ผ๋ฆฌ์ ์ธ ๋‹จ์œ„๋กœ ๋‚˜๋ˆˆ ๊ฒƒ ์‚ฌ์šฉ์ž๊ฐ€ ๋ฐฉ๋ฌธ ํ›„ 30๋ถ„...

SQL Analysis - SQL & DB

4 minute read

SQL์˜ ์ค‘์š”์„ฑ ๋ฐ์ดํ„ฐ ๊ด€๋ จ 3๊ฐœ์˜ ์ง๊ตฐ ๋ฐ์ดํ„ฐ ์—”์ง€๋‹ˆ์–ด Python, Java/Scalar SQL, DB ETL/ELT(airflow, DBT) Spark, Hadoop ๋ฐ์ดํ„ฐ ๋ถ„์„๊ฐ€ ...