Re: simple sql questions

From: Ray Chance <rchance_at_netcom.com>
Date: Wed, 8 Sep 1993 14:19:07 GMT
Message-ID: <rchanceCD1H3w.9D2_at_netcom.com>


David Benua (dbenua_at_panix.com) wrote:
: In <26il6n$9lh_at_elroy.jpl.nasa.gov> jason_at_woody.uucp (Jason Yi) writes:
 

: >Question 1.
 

: >I want to do something like this:
 

: >select * from mytable where mycolumn='ABC*';
: > ^
: > |
: > |
: > match anything that starts with ABC
 

: >Is this possible?
: Yes, try select * from mytable where mycolumn like 'ABC%'

Notice the use of the keyword 'like' and the character '%' - that's the difference between what you want and what you're doing

: >When you have a foriegn key, does the child table make a copy of it's
: >parent's or does it have a pointer referencing to it's parent?

: To misquote Firesign theatre: "No, No, No, you don't understand how
: radio works!"
 

: Child tables don't have pointers, or copies. Neither do parent tables.
: It's the _query_ which links the tables, not the database itself. This
: is the key to relational databases.

The "child" table stores the primary key to the "parent table" as a column; hence it's name 'foreign key'. In your query, you specify the "linkage", i.e., parent.primary = child.foreign.
: Dave
: >Thanks in advance

: --
: David Benua Internet: dbenua_at_panix.com
: Compu$erve: 72630,1416
:
Received on Wed Sep 08 1993 - 16:19:07 CEST

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