RE: quick mysql question
- From: "Holdsworth, Lynn" <Lynn.Holdsworth@xxxxxxxxxxx>
- To: <programmingblind@xxxxxxxxxxxxx>
- Date: Wed, 8 Apr 2009 15:09:59 +0100
Hi Alex,
Remember that the skip argument has a zero index, so Niran's example
would actually skip 10 records and bring back from the 11th row onwards.
Cheers, Lynn
-----Original Message-----
From: programmingblind-bounce@xxxxxxxxxxxxx
[mailto:programmingblind-bounce@xxxxxxxxxxxxx] On Behalf Of niran
Sent: 09 April 2009 03:10
To: programmingblind@xxxxxxxxxxxxx
Subject: Re: quick mysql question
The syntax of limit clause is
select .... limit skip , size
The limit clause will skip specified number of rows from the result and
return the rows specified in size. For example select * from users limit
10 , 10; will return 10 users starting from 10th user in the result set.
Alex Hall wrote:
> That makes a lot of sense. I have heard of limit 20, which will
> select the first 20 rows, but what is the comma? I guess I should say:
> what is the syntax of the limit clause? Thanks!
>
> Have a great day,
> Alex
>
>> ----- Original Message -----
>> From: "Holdsworth, Lynn" <Lynn.Holdsworth@xxxxxxxxxxx
>> To: <programmingblind@xxxxxxxxxxxxx
>> Date sent: Wed, 8 Apr 2009 13:04:14 +0100
>> Subject: RE: quick mysql question
>
>> Hi Alex,
>
>> I don't think you need row numbers to accomplish paging.
>
>> I've written some PHP code below, which you'll need to tweak a
> bit.
>
>> If you can put the page number in the querystring:-
>
>> http://www.something.com/somepage.php?page=3
>
>> Then you can tweak the SQL statement with a limit clause:-
>
>> <?php
>> ....
>> Extract($_GET); //exposes variables from the querystring
>> $recordsPerPage = 5; //Number of records on each page
>
>> //If page number not set, then set it to 1 If (!$page) { $page = 1; }
>
>> //Calculate the first record you want to retrieve on this page
>> //Index is zero-based $firstRecord = $recordsPerPage * ($page-1);
>
>> //Now build the SQL query with the limit clause $query = "select
>> <fieldNames From <tableName Where <whereClause Limit $firstRecord,
>> $recordsPerPage"; ....
>> ?
>
>> Let us know if this works for you.
>
>> Cheers, Lynn
>
>> Lynn Holdsworth
>> Web Analyst/Programmer - www.rnib.org.uk
>
>> -----Original Message-----
>> From: programmingblind-bounce@xxxxxxxxxxxxx
>> [mailto:programmingblind-bounce@xxxxxxxxxxxxx] On Behalf Of Alex
> Hall
>> Sent: 08 April 2009 12:47
>> To: programmingblind@xxxxxxxxxxxxx
>> Subject: Re: quick mysql question
>
>> Okay. How would I use this to control which records are
> displayed? Say
>> I have records 1-8, and the php page displays the first two, then
> the
>> next two, and so on, moving to the next two every time a "next"
> button
>> is clicked. How would the page know which two (or however many
> it was
>> set to display per page) to get? What if the user wants to go
> back? Does
>> this make sense?
>> Sorry if this comes out looking strange, I think my bn's ueb
> translator
>> is going crazy.
>
>> Have a great day,
>> Alex
>
>>> ----- Original Message -----
>>> From: "Octavian Rasnita" <orasnita@xxxxxxxxx
>>> To: <programmingblind@xxxxxxxxxxxxx
>>> Date sent: Wed, 8 Apr 2009 08:28:16 +0300
>>> Subject: Re: quick mysql question
>
>>> The indexes in a table are used for creating relations with the
>> records from
>>> other tables, and it would be a total mess if those indexes would
>> change.
>
>>> If you need to find how many records there are in a table, you
>> can simply
>>> count them using:
>
>>> select count(*) from table_name;
>
>>> Or you can put some conditions like:
>
>>> select count(*) from table_name where column1=123 and
>> another_column="abc"
>>> and another_one like '%bla%';
>
>>> --
>>> Octavian
>
>>> ----- Original Message -----
>>> From: "Alex Hall" <mehgcap@xxxxxxx
>>> To: <programmingblind@xxxxxxxxxxxxx
>>> Sent: Wednesday, April 08, 2009 6:21 AM
>>> Subject: Re: quick mysql question
>
>
>>>> Okay, so the numbering is lost if you delete. Is there a more
>> robust way
>>>> of numbering, so that you would have gotten:
>>>> 1, abc'
>>>> 2, 'ghi'
>>>> 3, 'kno'
>>>> instead? I need the index of each record to always be sequential
>> so that I
>>>> can know how many total records there are and also know which
>> ones I have
>>>> used in the displaying of all of them.
>
>>>> Have a great day,
>>>> Alex
>
>>>>> ----- Original Message -----
>>>>> From: "R. Haynie" <rhaynie@xxxxxxxxxxx
>>>>> To: programmingblind@xxxxxxxxxxxxx Date sent: Tue, 07 Apr 2009
>>>>> 22:51:24 -0400
>>>>> Subject: Re: quick mysql question
>
>>>>> An example is worth a thousand words...
>
>>>>> create table tbl1 (fld1 INTEGER AUTO_INCREMENT,
>>>>> fld2 char(3),
>>>>> PRIMARY KEY (fld1));
>
>>>>> insert into tbl1 (fld2) values ('abc'), ('def'), ('ghi'),
>>>> ('jkl');
>>>>> select * from tbl1;
>>>>> -- gives you:
>>>>> 1, 'abc'
>>>>> 2, 'def'
>>>>> 3, 'ghi'
>>>>> 4, 'jkl'
>
>>>>> delete from tbl1 where fld1 in (2, 4); insert into tbl1 (fld2)
>>>>> values ('mno'); select * from tbl1;
>>>>> -- gives you:
>>>>> 1, 'abc'
>>>>> 3, 'ghi'
>>>>> 5, 'mno'
>
>
>>>>> HTH.
>>>>> -Rodney
>
>
>
>
>>>>> Alex Hall wrote:
>>>>>> Hi all,
>>>>>> If I have a table of records and one column is an autoincrement,
>>>> what
>>>>>> happens when I delete a record? I want to use the autoincrement
>>>> as an
>>>>>> index, so records 1, 2, 3, and 4 exist where 1-4 are the indexes
>>>> of
>>>>>> the records, If you delete record 3, do you then have records 1,
>>>> 2,
>>>>>> and 3, or 1, 2, and 4? If it is the second case, is there a
>>>> better way
>>>>>> to have an index of each record? I need to know how many
>>>> recordsI am
>>>>>> using on a page (it is sort of a photo viewer so I need to know
>>>> which
>>>>>> pictures are being shown and how many more there are) and how
>>>> many
>>>>>> total there are to go. Thanks.
>
>>>>>> Have a great day,
>>>>>> Alex
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