문서의 이전 판입니다!

값없음

물리명	논리명	타입
값없음 유형	empty_type	문자
빈 값/NULL	empty_value	문자

CREATE TABLE ex_empty (
	empty_type VARCHAR(100) NULL,
	empty_value VARCHAR(100) NULL
);

INSERT INTO ex_empty (empty_type, empty_value) VALUES ('빈 값', '');
INSERT INTO ex_empty (empty_type, empty_value) VALUES ('NULL', NULL);

MySQL/MariaDB

SELECT * FROM ex_empty WHERE empty_value IS NULL OR empty_value = '';

SELECT * FROM ex_empty WHERE empty_value IS NOT NULL AND empty_value <> '';

SELECT * FROM ex_empty WHERE empty_value IS NULL OR empty_value = '';

SELECT * FROM ex_empty WHERE empty_value IS NOT NULL AND empty_value <> '';

SELECT * FROM ex_empty WHERE empty_value IS NULL;

SELECT * FROM ex_empty WHERE empty_value IS NOT NULL;

SELECT * FROM ex_empty WHERE empty_value IS NULL OR empty_value = '';

SELECT * FROM ex_empty WHERE empty_value IS NOT NULL AND empty_value <> '';