如何更改视图中虚拟列的数据类型？

Question

create or replace view ABC_VIEW(
   VEHICLEID, BRAND,
   MODEL, VEHICLE_TYPE,
   FUEL_TYPE, TRANSMISSION_TYPE,
   GEARBOX, DRIVE_TYPE,
   VEHICLE_NUMBER, PRICE, 
   "TEST Column"
) as 
  select VEHICLEID, BRAND,
         MODEL, VEHICLE_TYPE,
         FUEL_TYPE, TRANSMISSION_TYPE,
         GEARBOX, DRIVE_TYPE,
         VEHICLE_NUMBER, PRICE, 
         '' as "TEST Column" 
    from ABC;

默认情况下 "Test Column" 创建为 Char(1)。如何将其更改为 Number 数据类型？

请帮帮我。谢谢

Answer 1

您可能正在寻找 TO_NUMBER 功能。

试试这个：

create or replace view ABC_VIEW
(VEHICLEID,BRAND,MODEL,VEHICLE_TYPE,FUEL_TYPE,TRANSMISSION_TYPE,GEARBOX,DRIVE_TYPE,VEHICLE_NUMBER,PRICE,**"TEST Column"**) 
as select  VEHICLEID,BRAND,MODEL,VEHICLE_TYPE,FUEL_TYPE,
TRANSMISSION_TYPE,GEARBOX, DRIVE_TYPE,VEHICLE_NUMBER,PRICE,TO_NUMBER('') 
 from ABC;

Answer 2

点赞：

create or replace view v_abc as 
  select cast(null as number) test_column
    from dual;

测试：

select table_name, column_name, data_type 
  from all_tab_columns where table_name='V_ABC';

TABLE_NAME                     COLUMN_NAME                    DATA_TYPE 
------------------------------ ------------------------------ -------
V_ABC                          TEST_COLUMN                    NUMBER

如何更改视图中虚拟列的数据类型？

How to change the datatype of the Dummy Column in a View?

sql

oracle

sql-view