Oracle中函数使用技巧(1) - Decode(二)

SQL> create table t as select username,default_tablespace,lock_date from dba_users;
Table created.
SQL> select * from t;
USERNAME                        DEFAULT_TABLESPACE              LOCK_DATE
------------------------------ ------------------------------ ---------
SYS                             SYSTEM
SYSTEM                          SYSTEM
OUTLN                           SYSTEM
CSMIG                           SYSTEM
SCOTT                           SYSTEM
EYGLE                           USERS
DBSNMP                          SYSTEM
WMSYS                           SYSTEM                          20-OCT-04
8 rows selected.

SQL> select username,decode(lock_date,null,'unlocked','locked') status from t;
USERNAME                        STATUS
------------------------------ --------
SYS                             unlocked
SYSTEM                          unlocked
OUTLN                           unlocked
CSMIG                           unlocked
SCOTT                           unlocked
EYGLE                           unlocked
DBSNMP                          unlocked
WMSYS                           locked
8 rows selected.
SQL>





 select username,decode(lock_date,null,'unlocked') status from t;
USERNAME                        STATUS
------------------------------ --------
SYS                             unlocked
SYSTEM                          unlocked
OUTLN                           unlocked
CSMIG                           unlocked
SCOTT                           unlocked
EYGLE                           unlocked
DBSNMP                          unlocked
WMSYS
8 rows selected.