[EP-tech] Re: MySQL query to update a column value

Robert Berry robert.berry at liverpool.ac.uk
Thu Sep 20 11:57:02 BST 2012


Hi Claire,

Do not use the UPDATE statement. That's to alter records in the
database, not to change table structure.

You need to use ALTER TABLE (more info here:
http://dev.mysql.com/doc/refman/5.1/en/alter-table.html).

The syntax you want will be something like,

ALTER TABLE `eprint` SET `type` VARCHAR(255);

(Change the number inside varchar to the maximum number of characters
you want to be stored in the field.)

If you're uncomfortable writing SQL statements yourself it might be
better to use some client software to perform operations like this. I
can't make any recommendations but Google 'MySQL client software' and
see what comes up.

Best wishes,
Robert Berry


Claire Eskriett <C.Eskriett at brighton.ac.uk> writes:

>    Hi all
>
>
>    I’ve edited eprints.pl to change the property of an eprint field from
>    an integer to text but running update_database_structure has not
>    updated the eprint table. I’ve been advised to update manually using
>    MySQL and have come up with the following:
>
>
>    Use <database name>
>
>    Update eprint
>
>    Set type = text
>
>    Where field = num_pieces
>
>
>    I think this is ok – I’ve specified the table (eprint) and the field
>    that I want to update (num_pieces) and the column that I want updating
>    is ‘type’. The current row in the table is as follows:
>
>    Field                             | Type         | Null | Key | Default
>    | Extra
>
>    num_pieces            | int(11)      | YES  | MUL | NULL    |       |
>
>
>    Can anyone take pity on me and reassure me that this is ok? I ask as a
>    MySQL novice.
>
>
>    Many thanks for any advice!
>
>
>    Claire
>
>
>
>    Claire Eskriett, Systems Librarian
>
>    (Days of work are Mon, Tues, Thurs & Fri)
>
>    Information Services
>
>    Cockcroft Building
>
>    University of Brighton
>
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>
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>
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>
>    E: C.Eskriett at brighton.ac.uk
>
>
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