컬럼 정의 및 변경

설명

CREATE TABLE 문 또는 ALTER TABLE 문을 사용하여 BLOB/CLOB 타입 컬럼을 생성/추가/삭제할 수 있다.

참고 사항
예제

//creating a table and CLOB column

CREATE TABLE doc_t (doc_id VARCHAR(64) PRIMARY KEY, content CLOB);

 

//an error occurs when UNIQUE constraint is defined on CLOB column

ALTER TABLE doc_t ADD CONSTRAINT content_unique UNIQUE(content); -- Error

 

/an error occurs when creating an index on CLOB column

CREATE INDEX ON doc_t (content); -- Error

 

//creating a table and BLOB column

CREATE TABLE image_t (image_id VARCHAR(36) PRIMARY KEY, doc_id VARCHAR(64) NOT NULL, image BLOB);

 

//an error occurs when adding a BOLB column with NOT NULL constraint

ALTER TABLE image_t ADD COLUMN thumbnail BLOB NOT NULL; -- Error

 

//an error occurs when adding a BLOB column with DEFAULT attribute

ALTER TABLE image_t ADD COLUMN thumbnail2 BLOB DEFAULT BIT_TO_BLOB(X'010101'); -- Error