借助Oracle的Decode函数进行多值判断
发布时间：2021-11-29 11:47:27 所属栏目：教程 来源：互联网
导读：Decode函数的语法结构如下: 复制代码 代码如下: decode (expression, search_1, result_1) decode (expression, search_1, result_1, search_2, result_2) decode (expression, search_1, result_1, search_2, result_2, ...., search_n, result_n) decode (
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Decode函数的语法结构如下: 复制代码 代码如下: decode (expression, search_1, result_1) decode (expression, search_1, result_1, search_2, result_2) decode (expression, search_1, result_1, search_2, result_2, ...., search_n, result_n) decode (expression, search_1, result_1, default) decode (expression, search_1, result_1, search_2, result_2, default) decode (expression, search_1, result_1, search_2, result_2, ...., search_n, result_n, default) decode函数比较表达式和搜索字，如果匹配，返回结果；如果不匹配，返回default值；如果未定义default值，则返回空值。 以下是一个简单测试，用于说明Decode函数的用法: 复制代码 代码如下: 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.  （编辑：泉州站长网） 【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容! |
