complex query

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complex query

От:
Matt Gerginski <mattgerg@users.sourceforge.net>
Дата:
I have two tables, users and options.  The common element between the
tables is "username".  I want to select the "email" from "user" but only
if the "mailing_list" option is set to true in the "options" table.

Here are the tables:

select username, email from users;  username    |             email
---------------+--------------------------------joe           | joe@yahoo.comheidi         | heidi@localhostpayday        | brant@localhostfake          | fake@localhostmattgerg      | mattgerg@users.sourceforge.netgod           | god@heaven.org

select username, mailing_list from options;  username    | mailing_list
---------------+--------------payday        | tgod           | tfake          | tmattgerg      | t


I want to write a query that will return the emails of only the users
payday, god, fake, and mattgerg.

Is this at all possible?  I am new to sql, and I am having trouble.

--Matt



-- 
Matt Gerginski

Re: complex query

От:
"Victor Yegorov" <viy@pirmabanka.lv>
Дата:
* Matt Gerginski  [03.03.2003 19:11]:
> I have two tables, users and options.  The common element between the
> tables is "username".  I want to select the "email" from "user" but only
> if the "mailing_list" option is set to true in the "options" table.
> 
> Here are the tables:
> 
> select username, email from users;
>    username    |             email
> ---------------+--------------------------------
>  joe           | joe@yahoo.com
>  heidi         | heidi@localhost
>  payday        | brant@localhost
>  fake          | fake@localhost
>  mattgerg      | mattgerg@users.sourceforge.net
>  god           | god@heaven.org
> 
> select username, mailing_list from options;
>    username    | mailing_list
> ---------------+--------------
>  payday        | t
>  god           | t
>  fake          | t
>  mattgerg      | t
> 
> 
> I want to write a query that will return the emails of only the users
> payday, god, fake, and mattgerg.
> 
> Is this at all possible?  I am new to sql, and I am having trouble.
> 

select u.username, u.email from users as u, options as o where u.username =
o.username and o.mailing_list = true;


You'd better read some book on SQL.

-- 

Victor Yegorov
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