1.测试环境: A: OS: Microsoft Windows XP [版本 5.1.2600] DB: Oracle9i Enterprise Edition Release 9.2.0.1.0 - Production B: OS:SunOS 5.9 [ Solaris 9] DB:Oracle10g Enterprise Edition Release 10.1.0.3 - Production
A.CHAR默认长度是1, VARCHAR2必须指出长度 SQL> create table test (x char,y varchar2(10)) tablespace users; 表被创建 SQL> desc test; Name Type Nullable Default Comments ---- ------------ -------- ------- -------- X CHAR(1) Y Y VARCHAR2(10) Y
B. 尾部空格比较,对于char类型,’a’=’a ‘,对于varchar2类型,’b’<’b ‘
SQL> alter table test modify ( x char(10)); 表被改变 SQL> insert into test values(''''a '''',''''b ''''); 1 行 已插入 SQL> select * from test where x=''''a ''''; X Y ---------- ---------- a b SQL> select * from test where y=''''b ''''; X Y ---------- ---------- SQL> select * from test where y>''''b'''';