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Full Discussion: Selective delete in SQL
Top Forums UNIX for Dummies Questions & Answers Selective delete in SQL Post 302772861 by cero on Wednesday 27th of February 2013 03:02:23 AM
Old 02-27-2013
There most likely is a way to find out what is in the first 100 mb of the file, but that is not how databases work. One reason database systems were invented is that you do not have to bother with this kind of things, so the documentation for this is hard to find and understand.
I could tell you how to do this for Oracle systems if I'd know the exact version, but there would be a LOT research you'd have to do and I'm not sure if recreating the database wouldn't be less straining on your resources.
A quick google search revealed that shrinking mysql datafiles is not a built in feature for that database system, but there are tools that can do it. The native approach would be to add a datafile of the desired size, move all data there and drop the old ones (and I guess that is what those tools do).
Edit: Using tools like vi or awk on database files usually is a bad idea and will most likely corrupt your database.

Last edited by cero; 02-27-2013 at 04:30 AM..
 

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MSSQL_QUERY(3)															    MSSQL_QUERY(3)

mssql_query - Send MS SQL query

SYNOPSIS
mixed mssql_query (string $query, [resource $link_identifier], [int $batch_size]) DESCRIPTION
mssql_query(3) sends a query to the currently active database on the server that's associated with the specified link identifier. PARAMETERS
o $query - An SQL query. o $link_identifier - A MS SQL link identifier, returned by mssql_connect(3) or mssql_pconnect(3). If the link identifier isn't specified, the last opened link is assumed. If no link is open, the function tries to establish a link as if mssql_connect(3) was called, and use it. o $batch_size - The number of records to batch in the buffer. RETURN VALUES
Returns a MS SQL result resource on success, TRUE if no rows were returned, or FALSE on error. EXAMPLES
Example #1 mssql_query(3) example <?php // Connect to MSSQL $link = mssql_connect('KALLESPCSQLEXPRESS', 'sa', 'phpfi'); if (!$link || !mssql_select_db('php', $link)) { die('Unable to connect or select database!'); } // Do a simple query, select the version of // MSSQL and print it. $version = mssql_query('SELECT @@VERSION'); $row = mssql_fetch_array($version); echo $row[0]; // Clean up mssql_free_result($version); ?> NOTES
Note If the query returns multiple results then it is necessary to fetch all results by mssql_next_result(3) or free the results by mssql_free_result(3) before executing next query. SEE ALSO
mssql_select_db(3), mssql_connect(3). PHP Documentation Group MSSQL_QUERY(3)
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