Re: Is there any way we can exclude all possible values ?

From: xiaoyan <xiaoyezi.xyz_at_163.com>
Date: Sat, 30 Dec 2006 11:13:26 +0800
Message-ID: <002c01c72bc0$a55d0340$d810a8c0@buaad538c81ca1>

hi,

I am sorry for my poor english and thank you for your warmhearted reply. I mean I want to write a function which returns a predicate(like where clause), and the predicate is based on some column of a table,such as column 'COURSE_SCORE' in table 'STUDENT', and the predicate can excluede all the possible values of the column to be assigned, For example, the value of 'COURSE_SCORE' is perhaps 10,20,30,40.then I want the function returns 'COURSE_SCORE not in (10,20,30,40)',perhaps the predicate is like COURSE_SCORE ='a',here 'a' can be any character, because the value of the number column 'COURSE_SCORE' can not be character,I just want the functon returns a predicate (where clause),when I execute query aginst table 'STUDENT' with this predicate,I will get no data row, in fact, here I want to use VPD to implement some need. for example:here is the table STUDENT: STUDENT_ID STRUDENT_NAME COURSE_SCORE

    1           wxy           10
    2           feeling       20
    3           king          30
    4           merry         40

if not any where clause with the query,I will get all the data rows through the following query:

SQL> select * from student;

      STUDENT_ID  STRUDENT_NAME COURSE_SCORE
       1           wxy           10
       2           feeling       20
       3           king          30
       4           merry         40

if with a where clause like the following: SQL> select * from student where course_score no in (10,20,30,40) ;

SQL> select * from student where course_score='a';

SQL> select * from student where course_score='b'; .....

That is what I want to do, and based on some reason, the where clause must be based on one of the columns in the table.

I do not know if I have made my intent clear...

Best Regards and Happy New Year!

Original Message ----- From: Job Miller To: xiaoyezi.xyz_at_163.com Sent: Friday, December 29, 2006 11:04 PM Subject: Re: Is there any way we can exclude all possible values ?

your question doesn't make much sense to me. "we want to return COL=a" what's that mean?

give a better example and you might get some better help from the list.

are you talking about check constraints in the db? or are you talking about something in some code someone is writing?

xiaoyan <xiaoyezi.xyz_at_163.com> wrote: hi all,

       Is there any way we can exclude all possible values to be  assigned to a column in a table  without knowing the type of the column ?
       For example,suppose the name of the column is COL,if the type of the column is number,perhaps we want to return COL =a, since the type of the column is number,so the value to be assigned to it can not be 'a',through this we can exclude all the possible value.
       Though this seems to be queer, but in our project, we have this need.
       
       Can anyone tell my how to do?

       Thank you in advance
       Best Regards
       


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Received on Fri Dec 29 2006 - 21:13:26 CST