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adding an id field to a database after content



11:55 am on Jul 27, 2010 (gmt 0)

5+ Year Member

Hi all,

I have a database with content already in, but no unique primary id thingy.

How do I add one in phpmyadmin and make sure each table row is asigned a unique id number from 1 right through to the end, which might end be hundreds.



5:19 pm on Jul 27, 2010 (gmt 0)

WebmasterWorld Senior Member rocknbil is a WebmasterWorld Top Contributor of All Time 10+ Year Member

You'd add an auto_increment field:

alter table mytable add id int(11) primary key auto_increment;

Then you'd really want it to be the first column on the left, not that it has to be, it's just a bit of a standard. Simply put, you create a temporary table, select the fields in the order you want them, insert, drop old table, rename temp table. From the documentation,

1. Create a new table with the columns in the new order.
2. Execute this statement:
mysql> INSERT INTO new_table SELECT columns-in-new-order FROM old_table;
3. Drop or rename old_table.
4.Rename the new table to the original name:
mysql> ALTER TABLE new_table RENAME old_table;

If you select data by column-name, everything will function as it did, if you select anything by array index you will have to shift your array over by one.

// These are equivalent
$title = $row[0];
$title = $row['title'];

// These are equivalent
$title = $row[1]; // id is now 0
$title = $row['title'];


7:09 pm on Jul 27, 2010 (gmt 0)

5+ Year Member

Ah, auto_increment field - thats the term i was after.

Thanks for the help. Should be able to solve it now.


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