oracle创建列默认值,alter table添加带有默认值的列

lbx@ORCL> select * from v$version;

BANNER

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Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production

PL/SQL Release 11.2.0.3.0 - Production

CORE    11.2.0.3.0      Production

TNS for Linux: Version 11.2.0.3.0 - Production

NLSRTL Version 11.2.0.3.0 - Production

lbx@ORCL> create table t4(id number(3));

Table created.

lbx@ORCL> insert into t4 select level from dual connect by level<=10;

lbx@ORCL> commit;

lbx@ORCL> select * from t4;

ID

----------

1

2

3

4

5

6

7

8

9

10

lbx@ORCL> alter table t4 add(flag varchar2(10) default 'Y');

Table altered.

lbx@ORCL> select * from t4;

ID FLAG

---------- ----------

1 Y

2 Y

3 Y

4 Y

5 Y

6 Y

7 Y

8 Y

9 Y

10 Y

10 rows selected.

11G会加默认值哦，小心操作。。。

如果你本来有那字段，修改为增加默认值，原先为空的仍为空，后续增加的数据才会有默认值

lbx@ORCL> alter table t4 add (flag2 varchar2(10));

Table altered.

lbx@ORCL> select * from t4;

ID FLAG       FLAG2

---------- ---------- ----------

1 Y

2 Y

3 Y

4 Y

5 Y

lbx@ORCL> alter table t4 modify flag2 default 'N';

lbx@ORCL> insert into t4 (id) values(11);

1 row created.

lbx@ORCL> commit;

Commit complete.

lbx@ORCL> select * from t4;

ID FLAG       FLAG2

---------- ---------- ----------

1 Y

2 Y

3 Y

4 Y

5 Y

6 Y

7 Y

8 Y

9 Y

10 Y

11 Y          N