List:General Discussion« Previous MessageNext Message »
From:Grégoire Dubois Date:April 4 2003 4:20pm
Subject:Re: Primary key
View as plain text  
Victoria Reznichenko wrote:

>On Friday 04 April 2003 15:37, Grégoire Dubois wrote:
>
>  
>
>>In the following table, I declare ID as a PRIMARY KEY.  Is it then
>>necessary to add the parameters NOT NULL AUTO_INCREMENT?
>>
>>CREATE TABLE company (
>>    ID INT NOT NULL AUTO_INCREMENT,
>>
>>    name VARCHAR(30),
>>
>>    admin_ID INT,
>>
>>    PRIMARY KEY ID,
>>    INDEX admin_ID,
>>);
>>
>>Or can I just declare the table like that? Does creating a primary key
>>on an int immediatly involve this one to be not null, and to
>>auto-incrИment?
>>    
>>
>
>NOT NULL - yes, but if you want to have AUTO_INCREMENT column you should 
>declare it as AUTO_INCREMENT.
>
>
>  
>
Thank you very much for your reply.
But I read that a PRIMARY KEY is a "globally unique identifier" for a 
table. As it is an identifier, it should never be null (ok, that's what 
you said), and it should be unique... Then, if I don't set 
AUTO_INCREMENT to my column ID, it still should be unique, and then 
increment itself... No?

Thread
Conception - Tree - Recursivity -Address book - Query speedGrégoire Dubois2 Apr
  • RE: Conception - Tree - Recursivity -Address book - Query speedKevin Fries2 Apr
    • Re: Conception - Tree - Recursivity -Address book - Query speedGrégoire Dubois3 Apr
      • RE: Conception - Tree - Recursivity -Address book - Query speedKevin Fries3 Apr
  • Re: Conception - Tree - Recursivity -Address book - Query speedLeif B. Kristensen3 Apr
    • Primary keyGrégoire Dubois4 Apr
      • re: Primary keyVictoria Reznichenko4 Apr
        • Re: Primary keyGrégoire Dubois4 Apr
          • Re: Primary keyBruce Feist4 Apr
            • Re: Primary keyGrégoire Dubois5 Apr
Re: Primary keydpgirago5 Apr