This technique of using the db's auto increneting attribute works fine
unless you want the user to see the next id, invoice no, sample no etc
before they commit.
customer: " I want to see the next publisher id on the form before I
fill it out"
developer: "Why"
Customer: "Because I do"
Pete wrote:
>
> Doesn't mysql have sequences?
>
> In pgsql at least, you would use the following sql to create/insert into a
> table:
>
> create table mytable (id integer, blah varchar(64));
> create sequence mytable_id_seq start 1;
>
> insert into mytable values (nextval('mytable_id_seq'), 'some text');
>
> This nextval function is atomic, i.e. you get the value and it gets
> incremented without fear of some other connection grabbing the same value
> before it's been incremented. Other databases use slightly different
> syntax/etc, so ymmv with mysql. But you get the drift.
>
> Pete
>
> >I'm modifying some PHP code I found in MySQL PHP Shopping Cart to work
> >with a Books database.
> >
> >Basically the part add publisher (addpub.php)
> > 1 - obtains the highest publisher_id already in the table publisher
> >(fields publisher_id, publisher, description)
> > 2 - increments it to get the next value
> > 3 - sets up the form for you to enter the new publisher name and
> >description.
> > 4 - posts the data and clears the form everytime you hit the
> >"create" button
> >
> >The problem is that that it doesn't increment the publisher_id for a
> >second set of values, so you can end up with two identical
> >publisher_id's.
> >
> >My guess is that the MySQL database is buffering the data insertion
> >command and the value being read is the old maximum publisher_id, but
> >this is updated by the time you do the second insertion, so for the
> >third insertions, it is incremented.
> >
> >Is this correct?
> >If so, how do I fix it?
> >
> >My guess might be that I should close the connection after each post.
> >
> >Code is below.
> >
> >owl:terryc> cat addpub.php
> ><?php
> >
> >require("../config.ini");
> >
> >// database connection
> >mysql_connect("$host","$user","$pass");
> >
> >// database selection
> >mysql_select_db("$database");
> >
> >echo "<html><body bgcolor=\"#FFFFCC\">";
> >
> >// selects the max id from products and adds 1 to it to make new id
> >$result = mysql_query("select MAX(publisher_id) from publisher");
> >
> >echo "$result, <br>";
> >
> >/* some error checking if its the first item entered. We don't like
> > products with an ID of "0" */
> >$num_rows = @mysql_num_rows($result) or print("");
> >
> >
> >// get the max id to determine the next one
> >$s = mysql_fetch_row($result);
> >
> >
> >
> >
> >// test if its the table is empty, if it is, put a nice starting number
> >in, like 10001
> >if(empty($s)) {
> > $tsku = "10001";
> >}
> >
> >// otherwise just increment the high number
> >else {
> > $tsku = $s[0] + 1;
> >}
> >
> >// display the form
> >echo "<table border=0><form method=post action=\"addpub.php\">
> >
> > <tr><td>Publisher ID:</td><td>$tsku<input type=hidden
> >name=\"publisher_id\" value=\"$tsku\"></td></tr>";
> >?>
> > <tr><td>Publisher:</td><td><input name="publisher"
> >size=75></td></tr>
> > <tr><td>Description:</td><td><textarea cols=50 rows=10
> >name="description" wrap=virtual>
> > </textarea></td></tr>
> > <tr><td><input type=submit name=page
> >value="Create"></td></form></tr></table>
> ><?
> >
> >// page that inserts the values into the database
> >if($page == "Create") {
> >
> >mysql_query("insert into publisher
> >values('$publisher_id','$publisher','$description')");
> >
> >echo "Your publisher #$tsku has been created.";
> >
> >
> >}
> >
> >?>
> >owl:terryc>
> >--
> > Terry Collins {:-)}}} Ph(02) 4627 2186 Fax(02) 4628 7861
> > email: [EMAIL PROTECTED] www: http://www.woa.com.au
> > WOA Computer Services <lan/wan, linux/unix, novell>
> >
> > "People without trees are like fish without clean water"
> >
> >
> >--
> >SLUG - Sydney Linux User Group Mailing List - http://slug.org.au/
> >More Info: http://slug.org.au/lists/listinfo/slug
> >
>
> --
> SLUG - Sydney Linux User Group Mailing List - http://slug.org.au/
> More Info: http://slug.org.au/lists/listinfo/slug
--
SLUG - Sydney Linux User Group Mailing List - http://slug.org.au/
More Info: http://slug.org.au/lists/listinfo/slug
