SQL> create table t_nbr(a number);

Table created

SQL> insert into t_nbr values(1);

1 row inserted

SQL> insert into t_nbr values('');

1 row inserted

SQL> commit;

Commit complete

SQL> commit;

Commit complete

SQL> select * from t_nbr;

         A
----------
         1

SQL> select a,dump(a) from t_nbr;

         A DUMP(A)
---------- --------------------------------------------------------------------------------
         1 Typ=2 Len=2: 193,2
           NULL

SQL>

小结:

1,''和NULL在oracle存储皆视为NULL

ITPub博客

oracle之''空子符串与NULL是否相等

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