๐Ÿท IS NULL

IS NULL ์—ฐ์‚ฐ์ž๋Š” ๋ฐ์ดํ„ฐ ๊ฐ’์ด null์ธ ๊ฒฝ์šฐ๋ฅผ ์กฐํšŒํ•˜๊ณ ์ž ํ•  ๋•Œ ์‚ฌ์šฉํ•œ๋‹ค.
๐Ÿ’ก null์€ 0์ด๋‚˜ ๊ณต๋ฐฑ(space)๊ณผ๋Š” ์—„์—ฐํžˆ ๋‹ค๋ฆ„! 0์€ ์ˆซ์ž ๊ฐ’์ด๊ณ  ๊ณต๋ฐฑ์€ ๋ฌธ์ž ๊ฐ’์ด๋ฏ€๋กœ ๋‹ค๋ฅธ ์œ ํ˜•์˜ ๋ฐ์ดํ„ฐ ๊ฐ’์ด๋‹ค!

SELECT "ํ•„๋“œ๋ช…"
FROM "ํ…Œ์ด๋ธ”๋ช…"
WHERE "ํ•„๋“œ๋ช…" IS NULL

SELECT "ํ•„๋“œ๋ช…"
FROM "ํ…Œ์ด๋ธ”๋ช…"
WHERE "ํ•„๋“œ๋ช…" IS NOT NULL

๐Ÿท ํ”„๋กœ๊ทธ๋ž˜๋จธ์Šค(SQL-Kit IS NULL)๋ฌธ์ œ ํ’€์ด


1. ์ด๋ฆ„์ด ์—†๋Š” ๋™๋ฌผ์˜ ์•„์ด๋””

SELECT ANIMAL_ID
FROM ANIMAL_INS
WHERE NAME IS NULL
ORDER BY ANIMAL_ID

2. ์ด๋ฆ„์ด ์žˆ๋Š” ๋™๋ฌผ์˜ ์•„์ด๋””

SELECT ANIMAL_ID
FROM ANIMAL_INS
WHERE NAME IS NOT NULL
ORDER BY ANIMAL_ID ASC

3. NULL ์ฒ˜๋ฆฌํ•˜๊ธฐ

SELECT ANIMAL_TYPE, IFNULL(NAME,"No name") AS NAME, SEX_UPON_INTAKE
FROM ANIMAL_INS
ORDER BY ANIMAL_ID

IFNULL์„ ์‚ฌ์šฉํ•ด NULL์ผ๋•Œ๋ฅผ ์ฒ˜๋ฆฌํ•ด์ค€๋‹ค


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