mysql oracle对空值_注意Oracle与Mysql中的null值

在mysql中，null与''是不相同的，''会插入一个空字符串

mysql> select version();

+------------+

| version()  |

+------------+

| 5.5.18-log |

+------------+

1 row in set (0.00 sec)

mysql> create table goolen (name varchar(10) primary key);

Query OK, 0 rows affected (0.03 sec)

mysql> insert into goolen values('goolen');

Query OK, 1 row affected (0.00 sec)

mysql> insert into goolen values('');

Query OK, 1 row affected (0.00 sec)

mysql> insert into goolen values(null);

ERROR 1048 (23000): Column 'name' cannot be null

mysql> insert into goolen values('scott');

Query OK, 1 row affected (0.00 sec)

mysql> select * from goolen;

+--------+

| name   |

+--------+

|        |

| goolen |

| scott  |

+--------+

3 rows in set (0.00 sec)

在oracle中，null跟''是一样的，oracle都会理解为是null值；

SQL> select * from v$version where rownum=1;

BANNER

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

Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - 64bi

SQL> create table goolen(name varchar2(10) primary key);

Table created.

SQL> insert into goolen values('goolen');

1 row created.

SQL> insert into goolen values('');

insert into goolen values('')

*

ERROR at line 1:

ORA-01400: cannot insert NULL into ("SYS"."GOOLEN"."NAME")

SQL> insert into goolen values(null);

insert into goolen values(null)

*

ERROR at line 1:

ORA-01400: cannot insert NULL into ("SYS"."GOOLEN"."NAME")

SQL> insert into goolen values('scott');

1 row created.

SQL> select * from goolen;

NAME

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

goolen

scott

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