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  • Is there a good way to execute MySQL statements atomically via JDBC?

    - by javanix
    Suppose I have a table that contains valid data. I would like to modify this data in some way, but I'd like to make sure that if any errors occur with the modification, the table isn't changed and the method returns something to that effect. For instance, (this is kind of a dumb example, but it illustrates the point so bear with me) suppose I want to edit all the entries in a "name" column so that they are properly capitalized. For some reason, I want either ALL of the names to have proper capitalization, or NONE of them to have proper capitalization (and the starting state of the table is that NONE of them do). Is there an already-implemented way to run a batch update on the table and be assured that, if any one of the updates fails, all changes are rolled back and the table remains unchanged? I can think of a few ways to do this by hand (though suggestions are welcomed), but it'd be nice if there was some method I could use that would function this way. I looked at the java.sql.statement.executeBatch() command, but I'm not convinced by the documentation that my table wouldn't be changed if it failed in some manner.

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  • MySQL - are FK's useful / viable in a web app?

    - by yoda
    Hi all, I've encountered this discussion related to FK's and web applications. Basically some people say that FK's in web applications doesn't represent a real improvement and can even make the application slower in some cases. What do you guys think, what's your experience? -- A quote from Heikki Tuuri, creator of InnoDB engine, founder and CEO of Innobase: InnoDB checks foreign keys as soon as a row is updated, no batching is performed or checks delayed till transaction commit Foreign keys are often serious performance overhead, but help maintain data consistency Foreign Keys increase amount of row level locking done and can make it spread to a lot of tables besides the ones directly updated

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  • How to Display result of subquery rows as one column in MySQL?

    - by SIA
    Hi I have three tables Category, Movies and RelCatMov Category-table categoryid, categoryName 1 thriller 2 supsense 3 romantic 4 action 5 sci-fi Movies-table movieid, movieName 1 Avataar 2 Titanic 3 NinjaAssassin RelCatMov-table categoryid, MovieID 1 1 2 2 3 2 4 2 5 2 Now i Want to display a the record as MovieName Categories Titanic Suspense,Romantic,Sci-fi,action How to do this. I am writing a query select MovieName,(select categoryname from category b,relcatmov c where b.categoryid=c.categoryid and c.movieid=a.movieid) as categories from movies a; Error: Subquery returns more than one row!!! How to display the result of rows in one column? Please help!!!

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  • MySQL calling in Username to show instead of ID!

    - by Jess
    I have a users table, books table and authors table. An author can have many books, while a user can also have many books. (This is how my DB is currently setup). As I'm pretty new to So far my setup is like bookview.php?book_id=23 from accessing authors page, then seeing all books for the author. The single book's details are all displayed on this new page...I can get the output to display the user ID associated with the book, but not the user name, and this also applies for the author's name, I can the author ID to display, but not the name, so somewhere in the query below I am not calling in the correct values: SELECT users.user_id, authors.author_id, books.book_id, books.bookname, books.bookprice, books.bookplot FROM books INNER JOIN authors on books.book_id = authors.book_id INNER JOIN users ON books.book_id = users.user_id WHERE books.book_id=" . $book_id; Could someone help me correct this so I can display the author name and user name both associated with the book! Thanks for the help :)

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  • Safe to KILL a mysql process REPLACEing records in a large myisam table?

    - by threecheeseopera
    I have a REPLACE query running for a few days now on a few MyISAM tables, the largest having 20+million records. I need it to stop. It is, basically: REPLACE INTO really_large_table (a,b,c,d) SELECT e,f,g,h FROM big_table INNER JOIN huge_table ON big_table.x LIKE CONCAT('%', huge_table.y, '%'); I need to KILL it, and I am worried that I may corrupt really_large_table. Because the sub-query itself takes a significant amount of time, the REPLACEing probably occurs (relatively) infrequently; if this is true, does this make it less likely for the data to become corrupted? For the curious, here is the SO question asked about the query I am trying to kill.

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  • When does a MySQL Query actually execute in PHP?

    - by MJB
    This sounds like a really simple question, but I am new to PHP. If I have a statement like this: $r =& $db->query("insert into table (col1, col2) values (10, 20)"); Do I have to still execute it, or does it get executed when I reference it? I have another case where I have a select query, which seems logically to run only when I call fetchrow, but the code I am presented with (to fix) does not call execute or fetch.I would have expected it to, so I cannot tell if it is just that I don't get it, or that the missing execute statement is the problem. It also does not insert the record, but it does not throw an error I can find. Also, I am a little confused by the =& notation. I looked it up on google, and found a few mentions of it, but I am still not clear on it. Thanks.

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  • PDOStatement::bindParam() not setting AI value from MySQL insert?

    - by Alan
    I have a simple insert statement using PDO php class. $statement = $db->prepare('INSERT INTO demographics (id,location_id,male,ethnicity_id,birthyear) VALUES (:id,:location_id,:male,:ethnicity_id,:birthyear)'); $statement->bindParam(':id',$demo->id,PDO::PARAM_INT,4); $statement->bindParam(':location_id', $demo->locationid,PDO::PARAM_INT); $statement->bindParam(':male',$demo->male,PDO::PARAM_BOOL); $statement->bindParam(':ethnicity_id',$demo->ethnicityid,PDO::PARAM_INT); $statement->bindParam(':birthyear',$demo->birthyear,PDO::PARAM_INT); $statement->execute(); print_r($demo); Even though the statement executes correctly (row is correctly written), $demo-id is null. Any thoughts?

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  • MYSQL: how to search for fields that hold values sep. by commas?

    - by andufo
    hi. i have 2 tables: tags (id_tag,name) news (id,title,data,tags) The field newstags is a varchar(255). Im planning to put data like this in that field: "1,7,34" That means that a particular row in news is linked to tags 1, 7 and 34 from the tags table. Then, how can i search for ALL news records that have the 34 value (among others) in the tags field? Is there a better way to do this?

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  • rookie MySql question about paging; Is one query enough?

    - by Camran
    I have managed to get paging to work, almost. I want to display to the user, total nr of records found, and the currently displayed records. Ex: 4000 found, displaying 0-100. I am testing this with the nr 2 (because I don't have that many records, have like 20). So I am using LIMIT $start, $nr_results; Do I have to make two queries in order to display the results the way I want, one query fetching all records and then make a mysql_num_rows to get all records, then the one with the LIMIT ? I have this: mysql_num_rows($qry_result); $total_pages = ceil($num_total / $res_per_page); //$res_per_page==2 and $num_total = 2 if ($p - 10 < 1) { $pagemin=1; } else { $pagemin = $p - 10; } if ($p + 10 $total_pages) { $pagemax = $total_pages; } else { $pagemax = $p + 10; } Here is the query: SELECT mt.*, fordon.*, boende.*, elektronik.*, business.*, hem_inredning.*, hobby.* FROM classified mt LEFT JOIN fordon ON fordon.classified_id = mt.classified_id LEFT JOIN boende ON boende.classified_id = mt.classified_id LEFT JOIN elektronik ON elektronik.classified_id = mt.classified_id LEFT JOIN business ON business.classified_id = mt.classified_id LEFT JOIN hem_inredning ON hem_inredning.classified_id = mt.classified_id LEFT JOIN hobby ON hobby.classified_id = mt.classified_id ORDER BY modify_date DESC LIMIT 0, 2 Thanks, if you need more input let me know. Basically Q is, do I have to make two queries?

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  • How do I add a one-to-one relationship in MYSQL?

    - by alex
    +-------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------+-------------+------+-----+---------+-------+ | pid | varchar(99) | YES | | NULL | | +-------+-------------+------+-----+---------+-------+ 1 row in set (0.00 sec) +-------+---------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------+---------------+------+-----+---------+-------+ | pid | varchar(2000) | YES | | NULL | | | recid | varchar(2000) | YES | | NULL | | +-------+---------------+------+-----+---------+-------+ 2 rows in set (0.00 sec) This is my table. pid is just the id of the user. "recid" is a recommended song for that user. I hope to have a list of pid's, and then recommended songs for each person. Of course, in my 2nd table, (pid, recid) would be unique key. How do I do a one-to-one query for this ?

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  • Are Multi-column Primary Keys in MySQL a optimisation problem?

    - by David
    Been looking into using multi-column primary keys and as performance is extremely important with the size of traffic and database I need to know if there is anything to consider before I start throwing out the unique ID method on many of my tables and start using mulit column primary keys. So, what are the performance/optimisation pros/cons to using multi column primary keys versus a basic single column, auto-inc primary key?

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  • PHP / MYSQL: Database empties when I use a variable in the WHERE condition of the last mysql_query

    - by Christian Cugnet
    <?php require 'connect.php'; $search = $_POST["search"]; These two queries work fine. So I used their format for the one below. $result = mysql_query("SELECT * FROM `subjects` WHERE $search = `student_id`"); $result2 = mysql_query("SELECT * FROM `grades` WHERE $search = `student_id`"); while($row = mysql_fetch_array($result)) { $row2 = mysql_fetch_array($result2); echo"<table border='1'>"; echo "<tr>"; echo "<th>Subjects:</th>"; echo "<th>Current Mark:</th>"; echo "<th>Edit Mark:</th>"; echo"</tr>"; echo"<tr>"; echo "<td>". $row['c1'] ."</td>"; echo "<td>". $row2['m1'] ."</td>"; echo "<td><input type='text' name='m1'></td>"; echo "</tr>"; echo "<tr>"; echo "<td>". $row['c2'] ."</td>"; echo "<td>". $row2['m2'] ."</td>"; echo "<td><input type='text' name='m2'></td>"; echo "</tr>"; echo "<tr>"; echo "<td>". $row['c3'] ."</td>"; echo "<td>". $row2['m3'] ."</td>"; echo "<td><input type='text' name='m3'></td>"; echo "</tr>"; echo "<tr>"; echo "<td>". $row['c4'] ."</td>"; echo "<td>". $row2['m4'] ."</td>"; echo "<td><input type='text' name='m4'></td>"; echo "</tr>"; echo "<tr>"; echo "<td>". $row['c5'] ."</td>"; echo "<td>". $row2['m5'] ."</td>"; echo "<td><input type='text' name='m5'></td>"; echo "</tr>"; echo "<tr>"; echo "<td>". $row['c6'] ."</td>"; echo "<td>". $row2['m6'] ."</td>"; echo "<td><input type='text' name='m6'></td>"; echo "</tr>"; echo "<tr>"; echo "<td>". $row['c7'] ."</td>"; echo "<td>". $row2['m7'] ."</td>"; echo "<td><input type='text' name='m7'></td>"; echo "</tr>"; echo "</table>"; echo "<input type='submit' name='submit' value='Submit'>"; echo "</form>"; } $M1 = $_POST["m1"]; $M2 = $_POST["m2"]; $M3 = $_POST["m3"]; $M4 = $_POST["m4"]; $M5 = $_POST["m5"]; $M6 = $_POST["m6"]; $M7 = $_POST["m7"]; It works if I put numbers e.x. 11111 Otherwise it just enters blank spaces into the table. I've tried '".$search."' I've tried ".$search." mysql_query("UPDATE grades SET m1 = '$M1', m2 = '$M2',m3 = '$M3',m4 = '$M4',m5 = '$M5',m6 = '$M6',m7 = '$M7' WHERE $search = `student_id`"); ?> Table +------------+---+---+---+---+---+---+---+ |student_id|m1|m2|m3|m4|m5|m6|m7| +------------+---+---+---+---+---+---+---+ ===Database d1 == Table structure for table grades |------ |Column|Type|Null|Default |------ |//student_id//|int(5)|No| |m1|text|No| |m2|text|No| |m3|text|No| |m4|text|No| |m5|text|No| |m6|text|No| |m7|text|No| == Dumping data for table grades |11111| | | | | | | |11112|fg|fd|f|f|fd|f|f ===Database d1 == Table structure for table subjects |------ |Column|Type|Null|Default |------ |//student_id//|int(11)|No| |c1|text|No| |c2|text|No| |c3|text|No| |c4|text|No| |c5|text|No| |c6|text|No| |c7|text|No| == Dumping data for table subjects |11111|English|Math|Science|Sport|IT|Art|History |11112|grdgg|vsbvbbb|bdbbrfd|bdbrb|dbrbfbf|fbdfbdbf|dbfbdfb

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  • How do I select differing rows in two MySQL tables with the same structure?

    - by chiborg
    I have two tables, A and B, that have the same structure (about 30+ fields). Is there a short, elegant way to join these tables and only select rows where one or more columns differ? I could certainly write some script that creates the query with all the column names but maybe there is an SQL-only solution. To put it another way: Is there a short substitute to this: SELECT * FROM table_a a JOIN table_b b ON a.pkey=b.pkey WHERE a.col1 != b.col2 OR a.col2 != b.col2 OR a.col3 != b.col3 # .. repeat for 30 columns

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  • What NAS setup for syncing over the internet?

    - by Jamse
    I have family living a few hours away and have a lot of files that I would like to share - especially lots of folders of digital photos, but also documents etc. - partially so they can see them, partially so I can have access when I visit them and partially for backup / redundancy purposes. My current hard drives on my main machine are getting pretty full anyway, and I have a MythTV box where my music is currently stored, so I was thinking of getting a NAS anyway. And at the other end my family have a few computers, so they would probably benefit from a NAS too. My general idea (though I'm willing to shift on this if there are any bright ideas about other ways of achieving my objectives) is to get a matching pair of NASs and have them sync over the internet. (To cut down on bandwidth use I would get them in sync locally to start with.) Having read around as best I can it seems that syncing over the internet is generally only a feature on quite high end units. However, I have seen that QNAP seem to feature this on their TS-110 and TS-210 units, which might work (they call it "remote replication"). They seem pretty reasonably priced for what they are, but of course with buying 2 of them and then adding the drives (say 1TB or 2TB each) I'd be looking at about £400 total. So, I'm looking for recommendations really. I don't want to spend more than the QNAPs would cost me, but any other ideas would be most appreciated. I am comfortable with technology and tinkering around, but I don't have as much time for that as I would like, so I guess I would favour solutions that require less tinkering rather than more (even though that's less fun!). Any thoughts would be welcome, as would any comments from people who have used the QNAP boxes for this. Thanks in advance. Some specifications: Two-way syncing. Changes made at either end should be synced to the other. There shouldn't be one unit that is effectively a read-only mirror of the other. Not real time. The syncing doesn't need to be real time - if it updated, say, daily overnight that would be fine. Set and forget. I would prefer minimal user interaction once set up - it would be great if syncs were scheduled and automatic. OS independence. I am running Windows XP plus an Ubuntu-based MythTV box. At the other end there are Windows 7 and Windows XP machines, plus a networked TV set top box which I think can play files off the network. Machine independence. I would favour a system that is self-contained, i.e. not reliant on any particular PC being switched on. If the system had enough else going for it I could perhaps work around it at this end, where I only have one PC that's used as such, but it would be harder at the other where there are at least two PCs that might be accessing the files. Notifications. I guess things like getting an email notification if the syncing fell over for any reason would be useful, though it's not a deal breaker.

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  • mysql query help, take total sum from a table, and based on discount value on another table calcula

    - by vegatron
    hi I have a table called invoices: CREATE TABLE IF NOT EXISTS `si_invoices` ( `id` int(10) NOT NULL AUTO_INCREMENT, `biller_id` int(10) NOT NULL DEFAULT '0', `customer_id` int(10) NOT NULL DEFAULT '0', `type_id` int(10) NOT NULL DEFAULT '0', `inv_tax_id` int(10) NOT NULL, `date` date NOT NULL DEFAULT '0000-00-00', `unreg_customer` tinyint(1) NOT NULL DEFAULT '0', `discount` decimal(10,2) NOT NULL DEFAULT '0.00', `discount_type` tinyint(1) NOT NULL DEFAULT '0', PRIMARY KEY (`id`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci AUTO_INCREMENT=20 ; each invoice has items that are stored in invoice_items table : CREATE TABLE IF NOT EXISTS `si_invoice_items` ( `id` int(10) NOT NULL AUTO_INCREMENT, `invoice_id` int(10) NOT NULL DEFAULT '0', `quantity` int(10) unsigned NOT NULL DEFAULT '0', `product_id` int(10) DEFAULT '0', `warehouse_id` int(10) NOT NULL, `unit_price` decimal(25,2) DEFAULT '0.00', `total` decimal(25,2) DEFAULT '0.00', `description` text, PRIMARY KEY (`id`), KEY `invoice_id` (`invoice_id`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8 AUTO_INCREMENT=56 ; and tax table CREATE TABLE IF NOT EXISTS `si_tax` ( `tax_id` int(11) NOT NULL AUTO_INCREMENT, `tax_description` varchar(50) COLLATE utf8_unicode_ci DEFAULT NULL, `tax_percentage` decimal(25,6) DEFAULT '0.000000', `type` varchar(1) COLLATE utf8_unicode_ci DEFAULT NULL, `tax_enabled` varchar(1) COLLATE utf8_unicode_ci NOT NULL DEFAULT '1', PRIMARY KEY (`tax_id`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci AUTO_INCREMENT=5 ; here is what I want to do step 1: get the sum_total of the invoice Items for a speciefic invoice step 2: calculate the discount, in the invoice table I have a discount_type field : if its equal to 0 , then there will be no discount if its equal to 1 , the discount value will be stored in the discount field if its equal to 2 , the discount is a percentage of sum_total step 3: calculate the taxes based on inv_tax_id based on the tax id , I will look in the tax table , get the tax_percentage and multiply it by the (sum_total - discount) in short here is the equation $gross_total = $sum_total - $disount + taxes

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  • MySql - Select from - Don't Show Duplicate Words - maybe "on duplicate key"?

    - by ali
    hi, how can I insert "on duplicate key" in this Code to remove duplicate words? or is there a better method that you know? thank you!! this is my code: function sm_list_recent_searches($before = '', $after = '', $count = 20) { // List the most recent successful searches. global $wpdb, $table_prefix; $count = intval($count); $results = $wpdb->get_results( "SELECT `terms`, `datetime` FROM `{$table_prefix}searchmeter_recent` WHERE 3 < `hits` AND CHAR_LENGTH(`terms`) > 4 ORDER BY `datetime` DESC LIMIT $count"); if (count($results)) { foreach ($results as $result) { echo '<a href="'. get_settings('home') . '/search/' . urlencode($result->terms) . '">'. htmlspecialchars($result->terms) .'</a>'.", "; } } }

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  • Doubt in Stored Procedure MySql - how to return multiple values for a variable ?

    - by Eternal Learner
    Hi, I have a stored procedure below. I intend this procedure to return the names of all the movies acted by an actor. Create Procedure ActorMovies( In ScreenName varchar(50), OUT Title varchar(50) ) BEGIN Select MovieTitle INTO Title From Movies Natural Join Acts where Acts.ScreenName = 'ScreenName '; End; I make a call like Call ActorMovies(' Jhonny Depp',@movie); Select @move; The result I get is a Null set , which is not correct.I am expecting a set of movies acted by Jhonny Depp to be returned. I am not sure as to why this is happening?

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  • Mysql - Operand should contain 1 column(s) : What's wrong with the query...?

    - by SpikETidE
    Hi everybody.... I am trying to query a database to find the following If a customer searches for a hotel in a city between dates A and B, find and return the hotels in which rooms are free between the two dates. There will be more than one room in each room type(i.e. 5 Rooms in type A, 10 rooms in Type B etc) and we have to query the db to find only those hotels in which there is atleast one room free in atleast one type. This is my table structure.... **Structure for table 'reservations'** reservation_id hotel_id room_id customer_id payment_id no_of_rooms check_in_date check_out_date reservation_date **Structure for table 'hotels'** hotel_id hotel_name hotel_description hotel_address hotel_location hotel_country hotel_city hotel_type hotel_stars hotel_image hotel_deleted **Structure for table 'rooms'** room_id hotel_id room_name max_persons total_rooms room_price room_image agent_commision room_facilities service_tax vat city_tax room_description room_deleted And this is my query $city_search = '15'; $check_in_date = '29-03-2010'; $check_out_date = '31-03-2010'; $dateFormat_check_in = "DATE_FORMAT('$reservations.check_in_date','%d-%m-%Y')"; $dateFormat_check_out = "DATE_FORMAT('$reservations.check_out_date','%d-%m-%Y')"; $dateCheck = "$dateFormat_check_in >= '$check_in_date' AND $dateFormat_check_out <= '$check_out_date'"; $query = "SELECT $rooms.room_id, $rooms.room_name, $rooms.max_persons, $rooms.room_price, $hotels.hotel_id, $hotels.hotel_name, $hotels.hotel_stars, $hotels.hotel_type FROM $hotels,$rooms,$reservations WHERE $hotels.hotel_city = '$city_search' AND $hotels.hotel_id = $rooms.hotel_id AND $hotels.hotel_deleted = '0' AND $rooms.room_deleted = '0' AND $rooms.total_rooms - (SELECT SUM($reservations.no_of_rooms) as tot, $rooms.room_id as id FROM $reservations,$rooms WHERE $dateCheck GROUP BY $reservations.room_id) > '0'"; The number of rooms already reserved in each room type in each hotel will be stored in the reservations table... The query returns the error : Operand should contain 1 column(s) I tried running the sub-query alone but i don't get any result... And i have lost quite some amount of hair trying to de-bug this query from yesterday... What's wrong with this...? Or is there a better way to do what i mentioned above...? Thanks for your time...

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