๐Ÿ“Certificate/Engineer Information Processing

[์ •๋ณด์ฒ˜๋ฆฌ๊ธฐ์‚ฌ] ์‹ค๊ธฐ ํ”„๋กœ๊ทธ๋ž˜๋ฐ์–ธ์–ด 3๋ฌธ์ œ (11)

Sun A 2024. 9. 9. 22:59

1๏ธโƒฃ [SQL]

2020.3ํšŒ A

 ๋‹ค์Œ ์กฐ๊ฑด์„ ๋งŒ์กฑํ•˜๋ฉด์„œ, ๊ณผ๋ชฉ๋ณ„ ์ ์ˆ˜์˜ ํ‰๊ท ์ด 90์ด ์ƒ์ธ ๊ณผ๋ชฉ์ด๋ฆ„, ์ตœ์†Œ์ ์ˆ˜, ์ตœ๋Œ€์ ์ˆ˜๋ฅผ ๊ตฌํ•˜๋Š” SQL๋ฌธ์„ ์ž‘์„ฑํ•˜์‹œ์˜ค.

- ๋Œ€์†Œ๋ฌธ์ž๋ฅผ ๊ตฌ๋ถ„ํ•˜์ง€ ์•Š๋Š”๋‹ค.
- WHERE ๊ตฌ๋ถ„์„ ์‚ฌ์šฉํ•˜์ง€ ์•Š๋Š”๋‹ค.
- GROUP BY, HAVING๊ตฌ๋ฌธ์„ ๋ฐ˜๋“œ์‹œ ์‚ฌ์šฉํ•œ๋‹ค.
- ์„ธ๋ฏธ์ฝœ๋ก (;)์€ ์ƒ๋žต ๊ฐ€๋Šฅํ•˜๋‹ค.
- ๋ณ„์นญ(AS)์„ ์‚ฌ์šฉํ•ด์•ผ ํ•œ๋‹ค.

[์„ฑ์ ]

 

๊ณผ๋ชฉ์ฝ”๋“œ ๊ณผ๋ชฉ์ด๋ฆ„ ํ•™์  ์ ์ˆ˜
1000 ์ปดํ“จํ„ฐ๊ณผํ•™ A+ 95
2000 ์šด์˜์ฒด์ œ B+ 85
1000 ์ปดํ“จํ„ฐ๊ณผํ•™ B+ 85
2000 ์šด์˜์ฒด์ œ B 80
[๊ฒฐ๊ณผ]

 

๊ณผ๋ชฉ์ด๋ฆ„ ์ตœ์†Œ์ ์ˆ˜ ์ตœ๋Œ€์ ์ˆ˜
์ปดํ“จํ„ฐ๊ณผํ•™ 85 95
SELECT ๊ณผ๋ชฉ์ด๋ฆ„, MIN(์ ์ˆ˜) AS ์ตœ์†Œ์ ์ˆ˜, MAX(์ ์ˆ˜) AS ์ตœ๋Œ€์ ์ˆ˜ FROM ์„ฑ์ 
GROUP BY ๊ณผ๋ชฉ์ด๋ฆ„ HAVING AVG(์ ์ˆ˜) >= 90;

 

2๏ธโƒฃ [SQL]

2022.3ํšŒ A

STUDENT ํ…Œ์ด๋ธ”์—์„œ ์ •๋ณด๊ณผ ํ•™์ƒ 50๋ช…, ์ „๊ธฐ๊ณผ ํ•™์ƒ 100๋ช…, ์ „์‚ฐ๊ณผ ํ•™์ƒ 50๋ช…์˜ ์ •๋ณด๊ฐ€ ์ €์žฅ๋˜์–ด ์žˆ์„ ๋•Œ, ๋‹ค์Œ SQL๋ฌธ์˜ ์‹คํ–‰ ๊ฒฐ๊ณผ์— ๋”ฐ๋ฅธ ํŠœํ”Œ์˜ ์ˆ˜๋Š”? (๋‹จ, DEPT ์นผ๋Ÿผ์€ ํ•™๊ณผ๋ช…์ด๋‹ค.)

1) SELECT DEPT FROM STUDENT;
2) SELECT DISTINCT DEPT FROM STUDENT;
3) SELECT COUNT(DISTINCT DEPT) FROM STUDENT WHERE DEPT = '์ „์‚ฐ๊ณผ';
1) 200
2) 3
3) 1

1) ๋‹จ์ˆœ SELECT๋Š” ์กฐ๊ฑด๊ฒ€์ƒ‰์ด๊ธฐ ๋•Œ๋ฌธ์— ์ „์ฒด ํ…Œ์ด๋ธ”์˜ ํŠœํ”Œ ์ˆ˜ ์ด๋ฏ€๋กœ 200๊ฐœ์ด๋‹ค.

2) DISTINCT(์ค‘๋ณต์ œ๊ฑฐ)์˜ ๊ฒฝ์šฐ ๋™์ผํ•œ ํŠœํ”Œ์„ ์ œ๊ฑฐํ•˜๊ณ  ๊ฒ€์ƒ‰ํ•˜๊ธฐ ๋•Œ๋ฌธ์— ๊ฐ ๊ณผ๊ฐ€ 1๊ฑด์”ฉ ์ด 3๊ฑด์ด ์กฐํšŒ๋œ๋‹ค.

3) GROUP BY๊ฐ€ ์—†์„ ๊ฒฝ์šฐ ์ „์ฒด ํ…Œ์ด๋ธ”์—์„œ์˜ ํŠœํ”Œ ๊ฐœ์ˆ˜๋ฅผ COUNT๋ฅผ ํ†ตํ•ด ์ถœ๋ ฅํ•˜๊ธฐ ๋•Œ๋ฌธ์— ์ถœ๋ ฅ๊ฐ’์„ ํ‘œํ˜„ํ•œ 1๊ฐœ๊ฐ€ ํŠœํ”Œ์ด๋‹ค.

 

3๏ธโƒฃ [Python]

2023.3ํšŒ

๋‹ค์Œ Python ์ฝ”๋“œ์— ์•Œ๋งž๋Š” ์ถœ๋ ฅ๊ฐ’์„ ์ž‘์„ฑํ•˜์‹œ์˜ค.

a = "engineer information processing"
b = a[:3]
c = a[4:6]
d = a[29:]
e = b+c+d
print(e)
b = eng
c = ne
d = ing
engneng
  • [:3] = a์˜ ์‹œ์ž‘๋ถ€ํ„ฐ 2๋ฒˆ์งธ๊นŒ์ง€์ธ "eng"
  • [4:6] = 4๋ฒˆ์งธ๋ถ€ํ„ฐ 5๋ฒˆ์งธ๊นŒ์ง€์ธ "en"
  • [29:] = 29๋ฒˆ์งธ๋ถ€ํ„ฐ ๋งˆ์ง€๋ง‰๊นŒ์ง€์ธ "ng"

๋ชจ๋‘ ํ•ฉ์น˜๋ฉด engneng