distinguish between "-" and "_"

Hello,

When I run two different SQL requests, they return same result:

SELECT part_number, description FROM part WHERE part_number LIKE
"000-1_GB-01"

and

SELECT part_number, description FROM part WHERE part_number LIKE
"000-1-GB-01"

I expect the first one returns "not found" since there's no
"000-1_GB-01"
in the part table, only "000-1-GB-01". but both returns "000-1-GB-01".
Can anyone please tell me why?
where should I go to find the course ?
Thanks in advance.

Lei

>
>When I run two different SQL requests, they return same result:
>
>SELECT part_number, description FROM part WHERE part_number LIKE
>"000-1_GB-01"
>
>and
>
>SELECT part_number, description FROM part WHERE part_number LIKE
>"000-1-GB-01"

Were you aware that _ is a wildcard character, so your first query
could match "000-1QGB-01"? Solution: if you want a literal _, escape
it.

On May 21, 3:23 pm, gordonb.vr...@burditt.org (Gordon Burditt) wrote:
> >When I run two different SQL requests, they return same result:
>
> >SELECT part_number, description FROM part WHERE part_number LIKE
> >"000-1_GB-01"
>
> >and
>
> >SELECT part_number, description FROM part WHERE part_number LIKE
> >"000-1-GB-01"
>
> Were you aware that _ is a wildcard character, so your first query
> could match "000-1QGB-01"? Solution: if you want a literal _, escape
> it.

I didn't know that. Thanks for your information. -Lei

On 21 May, 23:23, gordonb.vr...@burditt.org (Gordon Burditt) wrote:
> >When I run two different SQL requests, they return same result:
>
> >SELECT part_number, description FROM part WHERE part_number LIKE
> >"000-1_GB-01"
>
> >and
>
> >SELECT part_number, description FROM part WHERE part_number LIKE
> >"000-1-GB-01"
>
> Were you aware that _ is a wildcard character, so your first query
> could match "000-1QGB-01"? Solution: if you want a literal _, escape
> it.

And don't use LIKE where it is not needed. In this situation you
should use =

On Mon, 21 May 2007 22:23:15 +0000, Gordon Burditt wrote:

>>
>>When I run two different SQL requests, they return same result:
>>
>>SELECT part_number, description FROM part WHERE part_number LIKE
>>"000-1_GB-01"
>>
>>and
>>
>>SELECT part_number, description FROM part WHERE part_number LIKE
>>"000-1-GB-01"
>
> Were you aware that _ is a wildcard character, so your first query
> could match "000-1QGB-01"? Solution: if you want a literal _, escape
> it.

The underscore will match any one character.
The % will match any charcters including none.

So LIKE "000-1_GB-01"
will ok "000-1AGB-01"
or "000-1XGB-01"
etc A-the underscore matches ANYTHING in this position.


And LIKE "000-1%GB-01"
will ok "000-1GB-01"
or "000-1XGB-01"
or "000-1XYZGB-01"
etc A-the percent matches anything that STARTS in
this position, including nothing.

Chris

Christopher Pomasl wrote:
> On Mon, 21 May 2007 22:23:15 +0000, Gordon Burditt wrote:
>
>>> When I run two different SQL requests, they return same result:
>>>
>>> SELECT part_number, description FROM part WHERE part_number LIKE
>>> "000-1_GB-01"
>>>
>>> and
>>>
>>> SELECT part_number, description FROM part WHERE part_number LIKE
>>> "000-1-GB-01"
>> Were you aware that _ is a wildcard character, so your first query
>> could match "000-1QGB-01"? Solution: if you want a literal _, escape
>> it.
>
> The underscore will match any one character.
> The % will match any charcters including none.
>
> So LIKE "000-1_GB-01"
> will ok "000-1AGB-01"
> or "000-1XGB-01"
> etc A-the underscore matches ANYTHING in this position.
>
>
> And LIKE "000-1%GB-01"
> will ok "000-1GB-01"
> or "000-1XGB-01"
> or "000-1XYZGB-01"
> etc A-the percent matches anything that STARTS in
> this position, including nothing.
>
> Chris
>
>

Chris,

To start with, get a handle on database design theory (it's not that
hard). Google for "database normalization". That should help get you
started.

--
==================
Remove the "x" from my email address
Jerry Stuckle
JDS Computer Training Corp.
jstucklex@attglobal.net
==================

== Quote from Jerry Stuckle (jstucklex@attglobal.net)'s article
> Christopher Pomasl wrote:
> > On Mon, 21 May 2007 22:23:15 +0000, Gordon Burditt wrote:
> >
> >>> When I run two different SQL requests, they return same result:
> >>>
> >>> SELECT part_number, description FROM part WHERE part_number LIKE
> >>> "000-1_GB-01"
> >>>
> >>> and
> >>>
> >>> SELECT part_number, description FROM part WHERE part_number LIKE
> >>> "000-1-GB-01"
> >> Were you aware that _ is a wildcard character, so your first query
> >> could match "000-1QGB-01"? Solution: if you want a literal _, escape
> >> it.
> >
> > The underscore will match any one character.
> > The % will match any charcters including none.
> >
> > So LIKE "000-1_GB-01"
> > will ok "000-1AGB-01"
> > or "000-1XGB-01"
> > etc A-the underscore matches ANYTHING in this position.
> >
> >
> > And LIKE "000-1%GB-01"
> > will ok "000-1GB-01"
> > or "000-1XGB-01"
> > or "000-1XYZGB-01"
> > etc A-the percent matches anything that STARTS in
> > this position, including nothing.
> >
> > Chris
> >
> >
> Chris,
> To start with, get a handle on database design theory (it's not that
> hard). Google for "database normalization". That should help get you
> started.

here's a good start from mysql's website:

http://dev.mysql.com/tech-resources/...alization.html
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