Postgresql 插入数据时自动截取一定长度的字符串

5.1.1.?自动截取字符串

CREATE TABLE test (c varchar(5));

现在开始插入数据库，每次增加一个长度

test=> INSERT INTO test VALUES ('1');INSERT 0 1test=> INSERT INTO test VALUES ('12');INSERT 0 1test=> INSERT INTO test VALUES ('123');INSERT 0 1test=> INSERT INTO test VALUES ('1234');INSERT 0 1test=> INSERT INTO test VALUES ('12345');INSERT 0 1test=> INSERT INTO test VALUES ('123456');ERROR:  value too long for type character varying(5)test=> INSERT INTO test VALUES ('1234567');ERROR:  value too long for type character varying(5)test=>

超出长度会提示 ERROR: value too long for type character varying(5)

通过 ::varchar(5) 截取5前五个字符，后面抛弃

test=> INSERT INTO test VALUES ('123456'::varchar(5));INSERT 0 1test=> INSERT INTO test VALUES ('1234567'::varchar(5));INSERT 0 1test=> INSERT INTO test VALUES ('12345678'::varchar(5));INSERT 0 1

超过的部分被自动截取

test=> select * from test;   c------- 1 12 123 1234 12345 12345 12345 12345(8 rows)