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MySQL 20λ²ˆμ§Έμˆ˜μ—… β–Ά GROUP BY와 HAVING ​​ 1. μ—΄μ˜ 그룹화​ ​ 예제 11-1) STUDENT ν…Œμ΄λΈ”μ— μžˆλŠ” ν•™μƒμ˜ μž…ν•™λ…„λ„λ³„ 그룹을 좜λ ₯ν•˜λΌ. A) mysql> select substring(stu_no, 1, 4) -> from student -> group by substring(stu_no, 1, 4); ​ ​ 예제 11-2) 각 μž…ν•™λ…„λ„λ³„ 총 학생 수λ₯Ό 좜λ ₯ν•˜λΌ. A) mysql> select substring(stu_no, 1, 4), count(*) -> from student -> group by substring(stu_no, 1, 4); ​ ​ 예제 11-3) λ“±λ‘ν•œ 학생에 λŒ€ν•˜μ—¬ ν•™λ²ˆ, λ“±λ‘νšŸμˆ˜, 각 학생이 받은 μž₯ν•™κΈˆμ˜ 전체 합을 좜λ ₯ν•˜λΌ. A) mysql> select stu_no,.. 2021. 2. 9.
MySQL 19λ²ˆμ§Έμˆ˜μ—… β–Ά ν†΅κ³„ν•¨μˆ˜ ​ 1. λͺ¨λ“  μ—΄μ˜ 선택(*)​ mysql> select * from circle;​ ​ ​ 2. SELECT절의 μˆ˜μ‹ μ§€κΈˆκΉŒμ§€ SELECT절의 λŒ€λΆ€λΆ„μ˜ μ˜ˆμ œλŠ” μ—΄μ˜ μ΄λ¦„λ§Œμ„ μ§€μ •ν–ˆμ§€λ§Œ μˆ˜μ‹μ—λŠ” λ¦¬ν„°λŸ΄, 계산 λ˜λŠ” 슀칼라 ν•¨μˆ˜λ₯Ό μ‚¬μš©ν•  μˆ˜λ„ μžˆλ‹€. ​ ​ 예제 10-1) 2019년에 λ“±λ‘ν•œ 학생에 λŒ€ν•œ ν•™λ²ˆ, 년도, ν•™κΈ°, μž₯ν•™κΈˆμ•‘, 납뢀총앑(λ“±λ‘κΈˆ-μž₯ν•™κΈˆ), λ‚©λΆ€κΈˆλΉ„μœ¨(납뢀총앑/λ“±λ‘κΈˆ*100), '%'을 좜λ ₯ν•˜μ‹œμ˜€. A) mysql> select stu_no, fee_year, fee_term, fee_total, jang_total, -> fee_pay "납뢀총앑", fee_pay/fee_total*100 "λ‚©λΆ€κΈˆλΉ„μœ¨", '%' -> from fee -> where fee_year = 2.. 2021. 2. 8.
MySQL 18λ²ˆμ§Έμˆ˜μ—… 9-11) μž₯ν•™κΈˆ μˆ˜λ Ήμ΄μ•‘μ΄ 500,000μ›μ—μ„œ 2,000,000원 사이에 ν¬ν•¨λ˜μ§€ μ•ŠλŠ” 각 ν•™μƒμ˜ ν•™λ²ˆμ„ 좜λ ₯ν•˜λΌ. A) mysql> select stu_no -> from fee -> group by stu_no -> having not(sum(ifnull(jang_total, 0)) between 500000 and 2000000); ​ ​ 9-12) μž…ν•™λ…„λ„κ°€ 2002λ…„λΆ€ν„° 2006λ…„κΉŒμ§€ μž…ν•™ν•œ ν•™μƒμ˜ ν•™λ²ˆκ³Ό μž…ν•™λ…„λ„λ₯Ό 좜λ ₯ν•˜λΌ.​ A) mysql> select stu_no, fee_year -> from fee -> where fee_div='Y' and fee_enter is not null -> and fee_year between 2012 and 2018; ​ ​ 9-13) μΆœμƒλ…„λ„κ°€ 19.. 2021. 2. 8.
MySQL 17λ²ˆμ§Έμˆ˜μ—… β–Ά NULL μ—°μ‚°μž ​ 예제 9-17) νœ΄λŒ€ν°μ„ κ°€μ§€κ³ μžˆλŠ” ν•™μƒμ˜ ν•™λ²ˆκ³Ό 이름, νœ΄λŒ€ν° 번호λ₯Ό λ‚˜νƒ€λ‚΄μ–΄λΌ. A) mysql> select stu_no, stu_name, mobile -> from student -> where mobile is not null; ​​ ​ 예제 9-18) νœ΄λŒ€ν°μ„ 가지고 μžˆμ§€ μ•Šμ€ ν•™μƒμ˜ ν•™λ²ˆκ³Ό 이름, νœ΄λŒ€ν° λ²ˆν˜Έκ°€ NULL인 κ²½μš°μ—λŠ” "νœ΄λŒ€ν° μ—†μŒ"을 λ‚˜νƒ€λ‚΄μ–΄λΌ. A) mysql> select stu_no, stu_name, ifnull(mobile, 'νœ΄λŒ€ν°μ—†μŒ') -> from student -> where mobile is null; ​ ​​ 예제 9-19) ν•™μƒμ˜ νœ΄λŒ€ν°λ²ˆν˜Έ(MOBILE)κ°€ 010이 μ•„λ‹Œ λͺ¨λ“  ν•™μƒμ˜ ν•™λ²ˆκ³Ό 이름, νœ΄λŒ€ν°λ²ˆν˜Έλ₯Ό 좜λ ₯ν•˜λΌ. (단, 휴.. 2021. 2. 8.
MySQL 16λ²ˆμ§Έμˆ˜μ—… 8-3) 각 학생에 λŒ€ν•˜μ—¬ μˆ˜κ°•μ‹ μ²­ κ³Όλͺ©μ½”λ“œ, μˆ˜κ°•ν•™μ μ„ λ‚˜νƒ€λ‚΄μ–΄λΌ. A) mysql> select stu_no, sub_code, att_point from attend where att_div = 'y'; ​ ​ ​ 8-4) μž₯ν•™κΈˆμ„ 받은 ν•™μƒμ˜ ν•™λ²ˆκ³Ό 이름을 λ‚˜νƒ€λ‚΄μ–΄λΌ. A) mysql> select distinct​ s.stu_no, stu_name → from student s, fee f​ → where s.stu_no = f.stu​_no and ifnull(jang_total, 0) > 0; ​ ​ ​ β–Ά SELECT λͺ…λ Ήλ¬Έ : WHERE절 ​ 1. 관계 μ—°μ‚°μžλ₯Ό μ‚¬μš©ν•˜λŠ” 쑰건 ​​ 예제 9-1) 성별이 μ—¬μžμΈ ν•™μƒμ˜ ν•™λ²ˆκ³Ό 이름, 성별, 생년월일을 좜λ ₯ν•˜λΌ. A) mysql> select.. 2021. 2. 8.
MySQL 15λ²ˆμ§Έμˆ˜μ—… β–Ά SELECT λͺ…λ Ήλ¬Έ 일뢀 μ ˆμ„ ν¬ν•¨ν•œ μˆ˜ν–‰ κ³Όμ • ​ 예제 7-3) μˆ˜κ°•μ‹ μ²­ ν…Œμ΄λΈ”(attend)μ—μ„œ 2006년도 1학기에 μˆ˜κ°• μ‹ μ²­ν•œ ν•™μƒμ˜ ν•™λ²ˆκ³Ό μˆ˜κ°•λ…„λ„, ν•™κΈ°, ꡐ과λͺ©μ½”λ“œ, κ΅μˆ˜μ½”λ“œλ₯Ό κ΅μˆ˜μ½”λ“œ μ˜€λ¦„μ°¨μˆœμœΌλ‘œ λ‚˜νƒ€λ‚΄μ–΄λΌ. ​ mysql> select stu_no, att_year, att_term, sub_code, prof_code → from attend → where att_year = '2016' and att_term = 1 → order by prof_code; ​ ​ 7-1) SELECT λͺ…λ Ήλ¬Έμ—λŠ” 6개의 절둜 κ΅¬μ„±λ˜μ–΄ μžˆλ‹€. 6개 절 μ€‘μ—μ„œ μƒλž΅μ΄ κ°€λŠ₯ν•œ μ ˆμ€ 무엇인가 ? A) group by, having, where, order by 절. select절과 from절 μ΄μ™ΈλŠ” μƒλž΅ κ°€.. 2021. 2. 8.
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