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mitcho
Starting Member
7 Posts |
 Posted - 2004-09-21 : 00:03:24
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| Hey everyone,I just signed up today as i am new to sql, and have a little problem i was hoping for some feedback.I have a table called Nurse (see below). Nurse has an attribute called Exp_date which is the expiry date of their license. Their licenses have to be renewed every 2 years so i am trying to write an Assertion to check this (see below). unfortunaltey i am quite new to this and am not sure if it will work. I was wondering if anyone could let me know if it is wrong or if it will work. if it is wrong can i have some suggestions.here is the Nurse table:CREATE TABLE Nurse(Nurse_ssn varchar(12),Lic_no varchar(9),Exp_date date NOT NULL,CONSTRAINT _PK PRIMARY KEY(Nurse_ssn),);here is my assertion to check that the license has been renewed in the last 2 years:CREATE ASSERTION expiry-constraint CHECK(SELECT Exp_dateFROM Nurse((Sysdate - Exp_date)< 2));This assertion is not for a specific database application; im learning from a text book and im not trying to get this to work on a system, im just doing it on paper. its a question im having trouble with.anyone help me with that?Thanks for anyone who is willing to help me...regards,mitchell pageregards,mitchell page |
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mitcho
Starting Member
7 Posts |
Posted - 2004-09-21 : 00:06:05
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| Why are Assertions better suited to express rules such as this? Why not just use check constraints? Can anyone tell me why??regards,mitchell page |
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robvolk
Most Valuable Yak
15732 Posts |
Posted - 2004-09-21 : 08:33:46
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| Please don't cross post:http://www.sqlteam.com/forums/topic.asp?TOPIC_ID=40147 |
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need help - SQL Assertion