小编xmo*_*xmo的帖子

# CREATE TABLE foo ( id serial, val integer );
CREATE TABLE
# INSERT INTO foo (val) VALUES ('1'), (2);
INSERT 0 2
# SELECT * FROM foo WHERE id='1';
 id | val 
----+-----
  1 |   1
(1 row)

这里，在插入和选择时，postgres 都会隐式地将带引号的字符串转换为整型，而不是引发类型错误，除非带引号的值非常明确地键入为 varchar：

# INSERT INTO foo (val) VALUES (varchar '1');
ERROR:  column "val" is of type integer 
        but expression is of type character varying
LINE 1: INSERT INTO foo (val) VALUES (varchar '1');
                                              ^
HINT:  You will need to rewrite …