SQL Guide
SQL Guide
SQL (Structed Query Language)
RDBMSμμ λ°μ΄ν°λ² μ΄μ€μ μ μμ μ‘°μμ μν λ°μ΄ν°λ² μ΄μ€ μΈμ΄
λ°μ΄ν°μ μ°Έμ‘°, λ³κ²½, μμ , κ³μ° λ± κ΄κ³ν λ°μ΄ν°λ² μ΄μ€μ κ·Έ μμ μλ ν μ΄λΈ λ° λ°μ΄ν°κ° νμ
λ°μ΄ν°λ² μ΄μ€μ κΈ°λ³Έ μ‘°μ
λ°μ΄ν°λ² μ΄μ€ μ‘°ν
λ°μ΄ν°λ² μ΄μ€ μμ±
λ°μ΄ν°λ² μ΄μ€ μ ν
.sql νμΌμμ SQL λ¬Έ μ°Έμ‘°
λ°μ΄ν°λ² μ΄μ€ μμ
ν μ΄λΈμ κΈ°λ³Έ μ‘°μ
λ°μ΄ν°λ² μ΄μ€μ ν μ΄λΈ μ‘°ν
ν μ΄λΈ μμ±
datatype
INTEGER
NUMERIC
CHAR
VARCHAR
DATE
ν μ΄λΈ μ»¬λΌ μ 보 νμ
κΈ°μ‘΄μ ν μ΄λΈμ λ μ½λ μΆκ°
κΈ°μ‘΄ ν μ΄λΈ λ μ½λ λ³κ²½
ν μ΄λΈμμ λ μ½λλ₯Ό μμ
ν μ΄λΈμ μμ
κΈ°μ‘΄μ ν μ΄λΈμ 컬λΌμ μΆκ°, μμ λλ λ³κ²½
ν μ΄λΈ μ΄λ¦ λ³κ²½
table-name (x) β table_name(o)
λ°μ΄ν° κ²μμ΄
SELECT
SELECT DISTINCT
WHERE
whereμ 쑰건
λ¬Έμμ΄ λΉν¨ (text)
μμΉμ λΉκ΅(numbers)
AND, OR, NOT λ±μ λ Όλ¦¬ μ°μ°
GROUP BY
νΉμ 컬λΌμ ν€μΌ ν©κ³λ νκ· μΌλ‘ νμ
μ§κ³ ν¨μ
COUNT
MAX /MIN
SUM
AVG
SELECT λ¬Έμ μ€ν μμ :
FROM β WHERE β GROUP BY β SELECT
Having
μ§κ³ ν¨μμ ν¨κ» μ¬μ©
HAVING vs WHERE
ORDER BY
κΊΌλΈ κ²°κ³Ό μ λ ¬
ASC(μ€λ¦μ°¨μ)(default) or DESC(λ΄)μμ°¨μ
BETWEEN
LIKE
% : 0λ¬Έμ μ΄μμ μμμ λ¬Έμμ΄
_ : μμμ λ¬Έμ
IN
WHEREμ ν¨κ» μ¬μ©νμ¬ μ¬λ¬ κ° μ§μ κ°λ₯
JOIN
VIEW
κ°μμ ν μ΄λΈ
νμ λ°μ΄ν°λ² μ΄μ€μ μ΅μ λ°μ΄ν°λ₯Ό νμ
νμ
κΈ°μ‘΄ ν μ΄λΈμ κ°κ³΅ν κ²μμ λ°μ΄ν° κ²μ
reference
Etc
How do I get SUM function in MySQL to return '0' if no values are found?
MySQL κ³μ°νκ±°λ λ¬Έμμ΄μ κ²°ν©ν΄μ νμνκΈ°, MySQL ν¨μ μ¬μ©νκΈ°
OracleSQL - μ€μ²© κ·Έλ£Ήν¨μ / λΆμν¨μ
sql group by 2κ° μ΄μ : λλ κΈ°μ€μ select μ μλ λκ°μ΄ μ μ΄μ£Όλ©΄ λλ€.
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