scheduled events in mysql load csv fileto mysqltab

How to Create Scheduled Events in MySQLhttp://www.sitepoint.com/how-to-create-mysql-events/

Craig Buckler Contributing Editor

Published July 20, 2011

Tweet Subscribe This is the third and last article in a series about database automation with triggers and events. If you’ve not done so already, please read How to Create Triggers in MySQL which introduces many of the concepts discussed here.

An event is similar to a trigger. However, rather than running in response to a data change, events can be scheduled to run any number of times during a specific period. In effect, it’s a database-only cron job.

Events have been supported in MySQL since version 5.1. They are ideal for maintenance tasks such as data archiving or report generation which can be scheduled during off-peak times.

Our Database PlanOur blog database has a problem. Old posts are marked as deleted rather than being removed from the `blog` table. Our table will grow indefinitely and become slower over time. We could purge the old posts but that would remove them forever. Therefore, we’ll move posts and their associated audit records to archive tables. The archive tables can grow without affecting the speed of the main web application and we can undelete old posts if necessary.

Two archive tables are required:

http://www.sitepoint.com/author/craig-buckler/

`blog_archive`: identical to the `blog` table except it does not require a deleted flag or an auto-incrementing ID.

àudit_archive`: identical to the àudit` table except the timestamp is not automatically generated and it does not require an auto-incrementing ID.

The following SQL creates both tables:

CREATE TABLE `blog_archive` (ìd` mediumint(8) unsigned NOT NULL,`title` text,`content` text,PRIMARY KEY (ìd`),

) ENGINE=InnoDB DEFAULT CHARSET=utf8 COMMENT='Blog posts archive';-- CREATE TABLE àudit_archive` (

ìd` mediumint(8) unsigned NOT NULL,`blog_id` mediumint(8) unsigned NOT NULL,`changetype` enum('NEW','EDIT','DELETE') NOT NULL,`changetime` timestamp NOT NULL,PRIMARY KEY (ìd`),KEY ìx_blog_id` (`blog_id`),KEY ìx_changetype` (`changetype`),KEY ìx_changetime` (`changetime`),CONSTRAINT `FK_audit_blog_archive_id` FOREIGN KEY

(`blog_id`) REFERENCES `blog_archive` (ìd`) ON DELETE CASCADE ON UPDATE CASCADE) ENGINE=InnoDB DEFAULT CHARSET=utf8;

Starting MySQL’s Event SchedulerMySQL events are executed by a special event scheduler thread. It’s disabled by default so use the following MySQL command can determine whether it’s running:

SHOW PROCESSLIST;

If the scheduler is running, at least two rows will be shown and one will have its user field set to “event_scheduler”. If only one row is returned, the scheduler is disabled and events will not run.

You can ensure the scheduler starts when MySQL is launched with the command-line option --event-scheduler=ON or setting event_scheduler=ON in your MySQL configuration file (my.cnf or my.ini on Windows).

Alternatively, you can start the scheduler from the MySQL command line:

SET GLOBAL event_scheduler = ON;

Creating an EventWe require a scheduled event which:

Copies posts from `blog` to `blog_archive` when the deleted flag is set to 1.

Copies the associated audit entries for those posts from àudit` to àudit_archive`.

Physically deletes archived posts from the `blog` table. Referential integrity has been defined with a foreign key so all associated audit entries for those posts will also be removed.

Assuming you have MySQL rights to create events, the basic syntax is:

CREATE EVENT èvent_name` ON SCHEDULE schedule[ON COMPLETION [NOT] PRESERVE] [ENABLE | DISABLE | DISABLE ON SLAVE]DO BEGIN

-- event bodyEND;

The schedule can be assigned various settings, e.g.

Run once on a specific date/time:AT ‘YYYY-MM-DD HH:MM.SS’e.g. AT ’2011-06-01 02:00.00′

Run once after a specific period has elapsed:AT CURRENT_TIMESTAMP + INTERVAL n [HOUR|MONTH|WEEK|DAY|MINUTE]e.g. AT CURRENT_TIMESTAMP + INTERVAL 1 DAY

Run at specific intervals forever:EVERY n [HOUR|MONTH|WEEK|DAY|MINUTE]e.g. EVERY 1 DAY

Run at specific intervals during a specific period:EVERY n [HOUR|MONTH|WEEK|DAY|MINUTE] STARTS date ENDS datee.g. EVERY 1 DAY STARTS CURRENT_TIMESTAMP + INTERVAL 1 WEEK ENDS ’2012-01-01 00:00.00′

An event is normally dropped once its schedule has expired (ON COMPLETION NOT PRESERVE). Set ON COMPLETION PRESERVE to prevent that behavior. The MySQL CREATE EVENT Syntax documentation provides further details.

We can now define our event (remembering to set the DELIMITER first). We’ll set it to run every week starting on a Sunday morning:

DELIMITER $$

CREATE EVENT `archive_blogs` ON SCHEDULE EVERY 1 WEEK STARTS '2011-07-24 03:00:00' DO BEGIN

-- copy deleted postsINSERT INTO blog_archive (id, title, content) SELECT id, title, contentFROM blogWHERE deleted = 1;

-- copy associated audit recordsINSERT INTO audit_archive (id, blog_id, changetype,

changetime) SELECT audit.id, audit.blog_id, audit.changetype,

audit.changetime FROM audit

JOIN blog ON audit.blog_id = blog.idWHERE blog.deleted = 1;

-- remove deleted blogs and audit entriesDELETE FROM blog WHERE deleted = 1;

END */$$

DELIMITER ;

This is a simple example but you could add more functionality, e.g. only move posts which were deleted at least 1 month ago and purge all archieved posts over 1 year old. I hope you’ve enjoyed this series and are considering database triggers and events in your next project.

Another way to approach this is to use MySql events for scheduling and LOAD DATA INFILE for importing CSVYour event code might look like this

DELIMITER $$

CREATE EVENT ev_update_from_csv

ON SCHEDULE EVERY 10 MINUTE

DO BEGIN

-- Import csv into temptable

LOAD DATA INFILE '/path/file.csv'

INTO TABLE temptable

FIELDS TERMINATED BY ','

LINES TERMINATED BY '\n'

IGNORE 1 LINES;

-- Do other processing and transfer (insert or update) to a factual table here

INSERT INTO realtable (col1, col2, ...)

SELECT (col1, col2, ...)

FROM temptable

-- Clear temptable

TRUNCATE temptable;

END $$

DELIMITER ;

http://dev.mysql.com/doc/refman/5.6/en/load-data.html

http://dev.mysql.com/doc/refman/5.1/en/create-event.html

The function accepts 4 parameters:1. filename (string): Path to csv file. Eg: myfile.csv2. startRow (int): First row in delete area

3. endRow (int): Last row in delete area

4. inner (boolean): decide whether rows deleted are from inner area or outer area

Now Let us consider various cases. I have a csv file with me named ‘test.csv’. Here is the screenshot of the same.

Example 1:$status = csv_delete_rows('test.csv', 3, 5, true);will delete the red part of:

Example 2:$status = csv_delete_rows('test.csv', 3, 5, false);will delete the red part of:

Example 3: Like in your situation, if you want to delete the first 100 rows, use this:$status = csv_delete_rows('test.csv', 0, 100);

$status = 5; } else { $status = 6; } }//end while if ($status < 5) { $finalcsvfile = implode("\n", $updatedcsv); fclose($fp); $fp = fopen($filename, "w"); fwrite($fp, $finalcsvfile); } fclose($fp); return $status;} else { die('File does not exist');}}

Export MySQL table to CSV using PHP

<?php

// Database Connection

$host="localhost";

$uname="root";

$pass="";

$database = "a2zwebhelp";

$connection=mysql_connect($host,$uname,$pass);

echo mysql_error();

//or die("Database Connection Failed");

$selectdb=mysql_select_db($database) or

die("Database could not be selected");

$result=mysql_select_db($database)

or die("database cannot be selected <br>");

// Fetch Record from Database

$output = "";

$table = ""; // Enter Your Table Name

$sql = mysql_query("select * from $table");

$columns_total = mysql_num_fields($sql);

// Get The Field Name

for ($i = 0; $i < $columns_total; $i++) {

$heading = mysql_field_name($sql, $i);

$output .= '"'.$heading.'",';

}

$output .="\n";

// Get Records from the table

while ($row = mysql_fetch_array($sql)) {

for ($i = 0; $i < $columns_total; $i++) {

$output .='"'.$row["$i"].'",';

}

$output .="\n";

}

// Download the file

$filename = "myFile.csv";

header('Content-type: application/csv');

header('Content-Disposition: attachment; filename='.$filename);

echo $output;

exit;

?>

Lets write a simple php program to import data from CSV files or read CSV file using PHP. The following program will read the csv file and display output in HTML table format. Once you get the data you can either display it in HTML format or save in your MySql database.

PHP Code

<?php

include( 'FileReader.php' );

include( 'CSVReader.php' );

$reader =& new CSVReader( new FileReader( 'countrylist.csv' ) );

// set the separator as comma

$reader->setSeparator( ',' );

$line = 0; // line tracking

// output

echo '<table cellpadding=2 cellspacing=1 bgcolor="#cdcdcd" border=0>';

while( false != ( $cell = $reader->next() ) ) {

if ( $line == 0 ) {

echo "<tr>\n";

echo "<td style='font: 12px Arial; font-weight: bold' nowrap> # </td>\n";

for ( $i = 0; $i < count( $cell ); $i++ ){

echo "<td nowrap style='font: 12px Arial; font-weight: bold'> Cell

{$i}</td>\n";

}

echo "</tr>\n";

}

echo "<tr>\n";

echo "<td bgcolor='".( ( $line % 2 ) == 0 ? '#efefef' : '#ffffff' )."'

style='font: 12px Arial;'>{$line}</td>\n";

for ( $i = 0; $i < count( $cell ); $i++ )

{

echo "<td bgcolor='".( ( $line % 2 ) ==0 ? '#efefef' : '#ffffff' )."'

style='font: 12px Arial;'>{$cell[$i]}</td>\n";

}

echo "</tr>\n";

$line++;

}

echo '<table>';

?>

All included files and required files are available in the zip file attached here.

Download Code Total Downloads: 505

Click here to Export MySQL table to CSV using PHP Code.

scheduled events in mysql load csv fileto mysqltab

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