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  • php, mySQL - how to create a table?

    - by user296516
    Hi guys, I have written a code that should check weather there is a table called imei.$addimei and, if not, create it... $userdatabase = mysqli_connect('localhost', 'root', 'marina', 'imei'); ... $result = mysqli_query($userdatabase, "SELECT * FROM imei".$addimei."" ); if ( !$result ) { echo('creating table...'); /// if no such table, make one! mysql_query ( $userdatabase, 'CREATE TABLE imei'.$addimei.'( ID int NOT NULL AUTO_INCREMENT, PRIMARY KEY(ID), EVENT varchar(15), TIME varchar(25), FLD1 varchar(35), FLD2 varchar(35), IP varchar(25), )' ); } Yet the CREATE TABLE somehow doesn't seem to work. Warning: mysql_query() expects parameter 1 to be string, object given in C:\xampp\xampp\htdocs\mobi\mainmenu.php on line 564 Any idea's what wrong? Thanks!

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  • Mysql InnoDB performance optimization and indexing

    - by Davide C
    Hello everybody, I have 2 databases and I need to link information between two big tables (more than 3M entries each, continuously growing). The 1st database has a table 'pages' that stores various information about web pages, and includes the URL of each one. The column 'URL' is a varchar(512) and has no index. The 2nd database has a table 'urlHops' defined as: CREATE TABLE urlHops ( dest varchar(512) NOT NULL, src varchar(512) DEFAULT NULL, timestamp timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP, KEY dest_key (dest), KEY src_key (src) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 Now, I need basically to issue (efficiently) queries like this: select p.id,p.URL from db1.pages p, db2.urlHops u where u.src=p.URL and u.dest=? At first, I thought to add an index on pages(URL). But it's a very long column, and I already issue a lot of INSERTs and UPDATEs on the same table (way more than the number of SELECTs I would do using this index). Other possible solutions I thought are: -adding a column to pages, storing the md5 hash of the URL and indexing it; this way I could do queries using the md5 of the URL, with the advantage of an index on a smaller column. -adding another table that contains only page id and page URL, indexing both columns. But this is maybe a waste of space, having only the advantage of not slowing down the inserts and updates I execute on 'pages'. I don't want to slow down the inserts and updates, but at the same time I would be able to do the queries on the URL efficiently. Any advice? My primary concern is performance; if needed, wasting some disk space is not a problem. Thank you, regards Davide

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  • MySQL how to sum subgroup first then sum total

    - by Sunry
    My data in table_1 and table_2. table_1 id_1 num ids_2 3 33 666,777,888 4 44 111,222,333 table_2 id_2 num 111 1 222 2 333 3 666 6 777 7 888 8 I only know how to do what I want with two steps: First LEFT JOIN to get: SELECT 1.id_1, sum(2.num) FROM table_1 AS 1 LEFT JOIN table_2 AS 2 on FIND_IN_SET(2.id_2, 1.ids_2) GROUP BY 1.id_1; id_1 sum(2.num) 3 6+7+8 4 1+2+3 Then LEFT JOIN with table_1 again to sum(table_1.num+sum(2.num)): id_1 sum(table_1.num+sum(table_2.num)) 3 6+7+8+33 4 1+2+3+44 Can I do it in only one SQL?

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  • Why can i read dirty rows in MySql

    - by acidzombie24
    I cant believe this, i always throught the below would be concurrency safe. I write to a row in one transaction and i am able to read the dirty value from another transaction/command/connection! Why is this possible (not my main question) isnt this not desired and cause more troubles!?! Anyways, i expected that once i write to a row nothing else will be able to read to the row until the transaction is finished. And at least if the row can be still read that the clean (original) value will be read. (but maybe that would cause problems as well if the transaction doesnt use the newly commited data from the other transaction when it is ran) I would like count to == 11. I thought this would be safe in all variants of sql. What can i do to either 1) Not read the dirty value but clean 2) Have that row be locked until the transaction is finished? static MySqlConnection MakeConn() { string connStr = "server=192.168.126.128;user=root;database=TestDB;port=3306;password=a;"; MySqlConnection conn = new MySqlConnection(connStr); conn.Open(); return conn; } static Semaphore sem1 = new Semaphore(1, 1); static Semaphore sem2 = new Semaphore(1, 1); static void Main2() { Console.WriteLine("Starting Test"); // sem1.WaitOne(); Console.WriteLine("1W"); sem2.WaitOne(); Console.WriteLine("2W"); Thread oThread = new Thread(new ThreadStart(fn2)); oThread.Start(); var conn = MakeConn(); var cmd = new MySqlCommand(@" CREATE TABLE IF NOT EXISTS Persons ( P_Id int NOT NULL, name varchar(255), count int, PRIMARY KEY (P_Id) )", conn); cmd.ExecuteNonQuery(); cmd.CommandText = "delete from Persons; insert into Persons(name, count) VALUES('E', '4');"; cmd.ExecuteNonQuery(); cmd.CommandText = "select count from Persons;"; var count = (int)cmd.ExecuteScalar(); Console.WriteLine("Finish inserting. v={0}", count); sem2.Release(); Console.WriteLine("2R"); sem1.WaitOne(); Console.WriteLine("1W"); Console.WriteLine("Starting transaction"); using (var tns = conn.BeginTransaction()) { cmd.CommandText = "update Persons set count=count+1"; cmd.ExecuteNonQuery(); cmd.CommandText = "select count from Persons;"; count = (int)cmd.ExecuteScalar(); Console.WriteLine("count is {0}", count); sem2.Release(); Console.WriteLine("2R"); sem1.WaitOne(); Console.WriteLine("1W"); count += 5; //10 cmd.CommandText = "update Persons set count=" + count.ToString(); cmd.ExecuteNonQuery(); cmd.CommandText = "select count from Persons;"; count = (int)cmd.ExecuteScalar(); Console.WriteLine("count is {0}", count); tns.Commit(); } Console.WriteLine("finished transaction 1"); sem2.Release(); Console.WriteLine("2R"); sem1.WaitOne(); Console.WriteLine("1W"); cmd.CommandText = "select count from Persons;"; count = (int)cmd.ExecuteScalar(); Console.WriteLine("count is {0}", count); sem2.Release(); Console.WriteLine("2R"); //sem1.WaitOne(); Console.WriteLine("1W"); } static void fn2() { int count; Console.WriteLine("Starting thread 2"); sem2.WaitOne(); Console.WriteLine("1W"); var conn = MakeConn(); var cmd = new MySqlCommand("", conn); sem1.Release(); Console.WriteLine("1R"); sem2.WaitOne(); Console.WriteLine("2W"); using (var tns = conn.BeginTransaction()) { cmd.CommandText = "update Persons set count=count+1"; cmd.ExecuteNonQuery(); cmd.CommandText = "select count from Persons;"; count = (int)cmd.ExecuteScalar(); Console.WriteLine("count is {0}", count); sem1.Release(); Console.WriteLine("1R"); sem2.WaitOne(); Console.WriteLine("2W"); tns.Commit(); } Console.WriteLine("finished transaction 2"); sem1.Release(); Console.WriteLine("1R"); sem2.WaitOne(); Console.WriteLine("2W"); cmd.CommandText = "select count from Persons;"; count = (int)cmd.ExecuteScalar(); Console.WriteLine("count is {0}", count); //should be 11. 4 + 1x2(one each thread) += 5 from first thread == 11 sem1.Release(); Console.WriteLine("1R"); } console Starting Test 1W 2W Starting thread 2 Finish inserting. v=4 2R 1W 1R 1W Starting transaction count is 5 2R 2W count is 6 1R 1W count is 10 finished transaction 1 2R 2W finished transaction 2 1R 1W count is 10 2R 2W count is 10 1R

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  • set difference in SQL query

    - by TheObserver
    I'm trying to select records with a statement SELECT * FROM A WHERE LEFT(B, 5) IN (SELECT * FROM (SELECT LEFT(A.B,5), COUNT(DISTINCT A.C) c_count FROM A GROUP BY LEFT(B,5) ) p1 WHERE p1.c_count = 1 ) AND C IN (SELECT * FROM (SELECT A.C , COUNT(DISTINCT LEFT(A.B,5)) b_count FROM A GROUP BY C ) p2 WHERE p2.b_count = 1) which takes a long time to run ~15 sec. Is there a better way of writing this SQL?

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  • Newbie question - MySQL index size

    - by Tommy
    I've just started to investigating how I should optimize my database. Indexing seems to be a good idea, so I want to index a VARCHAR column, the engine is MyISAM. From what I've read, I understand that an index is limited to a size of 1000 bytes. A VARCHAR character is 3 bytes in size. Does this mean that if I want to index a VARCHAR column with 50 rows, I need an index prefix of 6 characters? I came to that number by dividing 1000 with the row number 50, then the bytesize per character that is 3. 1000/50/3=6,66. It seems a little complicated, so I'm just wondering if I'm thinking right? It seems weird to me that you'd only be able to index 333 rows in a VARCHAR column, using a prefix of 1 character.

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  • Multiple many-to-many JOINs in a single mysql query without Cartesian Product

    - by VWD
    At the moment I can get the results I need with two seperate SELECT statements SELECT COUNT(rl.refBiblioID) FROM biblioList bl LEFT JOIN refList rl ON bl.biblioID = rl.biblioID GROUP BY bl.biblioID SELECT GROUP_CONCAT( CONCAT_WS( ':', al.lastName, al.firstName ) ORDER BY al.authorID ) FROM biblioList bl LEFT JOIN biblio_author ba ON ba.biblioID = bl.biblioID JOIN authorList al ON al.authorID = ba.authorID GROUP BY bl.biblioID Combining them like this however SELECT GROUP_CONCAT( CONCAT_WS( ':', al.lastName, al.firstName ) ORDER BY al.authorID ), COUNT(rl.refBiblioID) FROM biblioList bl LEFT JOIN biblio_author ba ON ba.biblioID = bl.biblioID JOIN authorList al ON al.authorID = ba.authorID LEFT JOIN refList rl ON bl.biblioID = rl.biblioID GROUP BY bl.biblioID causes the author result column to have duplicate names. How can I get the desired results from one SELECT statement without using DISTINCT? With subqueries?

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  • getting a date array from a mysql database?

    - by user296516
    Hi guys, I have a database with date field is this format "2010.06.11. | 10:26 13" What is need is a php array that would hold all the different dates, .i.e. array[0] = "2010.06.09." array[1] = "2010.06.10." array[2] = "2010.06.11." Currently I am doing it by selecting the whole table, then looping through the result and adding the date substr to an array if it is not already there. But maybe there is a faster way? Thanks.

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  • mysql concat all field table

    - by hafizan
    Is there a way we can concat all field in the table(1 sql statement)(automatic) ? The reason was before user updated or delete a record,the record will push to another table for future reference.

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  • data in mysql show after barcode split and matches character

    - by klox
    i need some code for the next step..this my first step: <script> $("#mod").change(function() { var barcode; barCode=$("#mod").val(); var data=barCode.split(" "); $("#mod").val(data[0]); $("#seri").val(data[1]); var str=data[0]; var matches=str.matches(/EE|[EJU]).*(D)/i); }); </script> after matches..i want the result can connect to data base then show data from table inside <div id="value">...how to do that?

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  • Return order of MySQL SHOW COLUMNS

    - by rich
    Hey guys. Simple one this, but one I can't seem to find any information on so here goes. I need to find the columns in a specific table, which is no problem.... SHOW COLUMNS FROM tablename LIKE '%ColumnPrefix%'; But I need to know what order they will be returned, preferable by choosing to order the results ascending alphabetically. I have had no luck with using ORDER BY Field. Any ideas? Cheers!

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  • MySQL - display rows of names and addresses grouped by name, where name occures more than once

    - by Stoob
    I have two tables, "name" and "address". I would like to list the last_name and joined address.street_address of all last_name in table "name" that occur more than once in table "name". The two tables are joined on the column "name_id". The desired output would appear like so: 213 | smith | 123 bluebird | 14 | smith | 456 first ave | 718 | smith | 12 san antonia st. | 244 | jones | 78 third ave # 45 | 98 | jones | 18177 toronto place | Note that if the last_name "abernathy" appears only once in table "name", then "abernathy" should not be included in the result. This is what I came up with so far: SELECT name.name_id, name.last_name, address.street_address, count(*) FROM `name` JOIN `address` ON name.name_id = address.name_id GROUP BY `last_name` HAVING count(*) > 1 However, this produces only one row per last name. I'd like all the last names listed. I know I am missing something simple. Any help is appreciated, thanks!

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  • JDBC with MySQL

    - by Josh K
    I'm working on getting my database to talk to my Java programs. What do I need to get started? Having already read through (and been thoroughly confused, something that does not happen often) with some other turorials I figured I'd best ask here. How do I import a jar file from the local directory? Can someone give me a quick and dirty sample program using the JDBC?

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  • help optimize sql query

    - by msony
    I have tracking table tbl_track with id, session_id, created_date fields I need count unique session_id for one day here what i got: select count(0) from ( select distinct session_id from tbl_track where created_date between getdate()-1 and getdate() group by session_id )tbl im feeling that it could be better solution for it

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  • Sort a List<T> using query expressions - LINQ C#

    - by Dan Yack
    I have a problem using Linq to order a structure like this : public class Person { public int ID { get; set; } public List<PersonAttribute> Attributes { get; set; } } public class PersonAttribute { public int ID { get; set; } public string Name { get; set; } public string Value { get; set; } } A person might go like this: PersonAttribute Age = new PersonAttribute { ID = 8, Name = "Age", Value = "32" }; PersonAttribute FirstName = new PersonAttribute { ID = 9, Name = "FirstName", Value = "Rebecca" }; PersonAttribute LastName = new PersonAttribute { ID = 10, Name = "LastName", Value = "Johnson" }; PersonAttribute Gender = new PersonAttribute { ID = 11, Name = "Gender", Value = "Female" }; I would like to use LINQ projection to sort a list of persons ascending by the person attribute of my choice, for example, sort on Age, or sort on FirstName. I am trying something like string mySortAttribute = "Age" PersonList.OrderBy(p => p.PersonAttribute.Find(s => s.Name == mySortAttribute).Value); But the syntax is failing me. Any clues? Thanks in advance!

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  • php, mySQL & AJAX: Unable to use sessions across the scripts in the same domain

    - by Devner
    Hi all, I have the following pages: page1.php, page2.php and page3.php. Code in each of them is as below CODE: page1.php <script type="text/javascript"> $(function(){ $('#imgID').upload({ submit_to_url: "page2.php", file_name: 'myfile1', description : "Image", limit : 1, file_types : "*.jpg", }) }); </script> <body> <form action="page3.php" method="post" enctype="multipart/form-data" name="frm1" id="frm1"> //Some other text fields <input type="submit" name="submit" id="submit" value="Submit" /> </form> </body> page2.php <?php session_start(); $a = $_SESSION['a']; $b = $_SESSION['b']; $c = $_SESSION['c']; $res = mysql_query("SELECT col FROM table WHERE col1 = $a AND col2 = $b AND col3 = $c LIMIT 1"); $num_rows = mysql_num_rows($res); echo $num_rows; //echos 0 when in fact it should have been 1 because the data in the Session exists. //Ok let's proceed further //... Do some stuff... //Store some more values and create new session variables (and assume that page1.php is going to be able to use it) $_SESSION['d'] = 'd'; $_SESSION['e'] = 'e'; $_SESSION['f'] = 'f'; if (move_uploaded_file($_FILES['file']['tmp_name'], $file)) { echo "success"; } else { echo "error ".$_FILES['file']['error']; } ?> page3.php <?php session_start(); if( isset($_POST['submit']) ) { //These sessions are non-existent although the AJAX request //to page2.php may have created them when called via AJAX from within page1.php echo $_SESSION['d'].$_SESSION['e'].$_SESSION['f']; ?> } ?> As the code says it I am posting some info via AJAX call from page1.php to page2.php. page2.php is supposed to be able to use the session values from page1.php i.e. $_SESSION['a'], $_SESSION['b'] and $_SESSION['c'] but it does not. Why? How can I fix this? page2.php is creating some more sessions after some processing is done and a response is sent back to page1.php. The submit button of the form on page1.php is hit and the page gets POST'ed to page3.php. But when the SESSION info that gets created in page2.php is echoed, it's blank signifying that SESSIONS from page2.php are not used. How can I fix this? I looked over a lot of information and have spent about 50 hours trying to do different things with my scripts before arriving at the above conclusions. My app. is custom made using function (not OOPS) and does not use any PHP frameworks & I am not even about to use any as my knowledge of OOP concepts is limited any many frameworks are object oriented. I came across race conditions, but the solutions provided don't help too much. One more solution of using DB to hold sessions and seek and retrieve from DB is the last thing on my mind and I really want to avoid creating table, coding and maintaining code for a task as simple as just keeping sessions across pages in the same domain. So my request is: Is there a way that I can solve the above problem(s) via simple coding in present conditions? Any help is appreciated. Thank you.

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  • What is an index in MySQL?

    - by Eric
    http://i.imgur.com/JdsUK.jpg I created a table like the picture above. What are the "Indexes"? primary key? unique? It works well without setting indexes.. What do they do? why do I need them? Also, I set all String fields to TEXT because I didn't know how many characters I need. Is this a good idea? I don't see any difference. Thanks!

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  • Use of HAVING in MySQL

    - by KBrian
    I have a table from which I need to select all persons that have a first name that is not unique and that that set should be selected only if among the persons with a similar first name, all have a different last name. Example: FirstN LastN Bill Clinton Bill Cosby Bill Maher Elvis Presley Elvis Presley Largo Winch I want to obtain FirstN LastN Bill Clinton or FirstN LastN Bill Clinton Bill Cosby Bill Maher I tried this but it does not return what I want. SELECT * FROM Ids GROUP BY FirstN, LastN HAVING (COUNT(FirstN)>1 AND COUNT(LastN)=1)) [Edited my post after Aleandre P. Lavasseur remark]

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  • Mysql Database Question about Large Columns

    - by murat
    Hi, I have a table that has 100.000 rows, and soon it will be doubled. The size of the database is currently 5 gb and most of them goes to one particular column, which is a text column for PDF files. We expect to have 20-30 GB or maybe 50 gb database after couple of month and this system will be used frequently. I have couple of questions regarding with this setup 1-) We are using innodb on every table, including users table etc. Is it better to use myisam on this table, where we store text version of the PDF files? (from memory usage /performance perspective) 2-) We use Sphinx for searching, however the data must be retrieved for highlighting. Highlighting is done via sphinx API but still we need to retrieve 10 rows in order to send it to Sphinx again. This 10 rows may allocate 50 mb memory, which is quite large. So I am planning to split these PDF files into chunks of 5 pages in the database, so these 100.000 rows will be around 3-4 million rows and couple of month later, instead of having 300.000-350.000 rows, we'll have 10 million rows to store text version of these PDF files. However, we will retrieve less pages, so again instead of retrieving 400 pages to send Sphinx for highlighting, we can retrieve 5 pages and it will have a big impact on the performance. Currently, when we search a term and retrieve PDF files that have more than 100 pages, the execution time is 0.3-0.35 seconds, however if we retrieve PDF files that have less than 5 pages, the execution time reduces to 0.06 seconds, and it also uses less memory. Do you think, this is a good trade-off? We will have million of rows instead of having 100k-200k rows but it will save memory and improve the performance. Is it a good approach to solve this problem and do you have any ideas how to overcome this problem? The text version of the data is used only for indexing and highlighting. So, we are very flexible. Thanks,

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  • mysql - joining three tables with HAVING

    - by Qiao
    I have table: id name type where "type" is 1 or 2 I need to join this table with two other. Rows with "type = 1" should be joined with first table, and =2 with second. Something like SELECT * FROM tbl INNER JOIN tbl_1 ON tbl.name = tbl_1.name HAVING tbl.type = 1 INNER JOIN tbl_2 ON tbl.name = tbl_2.name HAVING tbl.type = 2 But it does not working. How it can be implemented?

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  • Tricky MySQL Query for messaging system in Rails - Please Help

    - by ole_berlin
    Hi, I'm writing a facebook style messaging system for a Rails App and I'm having trouble selecting the Messages for the inbox (with will_paginate). The messages are organized in threads, in the inbox the most recent message of a thread will appear with a link to it's thread. The thread is organized via a parent_id 1-n relationship with itself. So far I'm using something like this: class Message < ActiveRecord::Base belongs_to :sender, :class_name => 'User', :foreign_key => "sender_id" belongs_to :recipient, :class_name => 'User', :foreign_key => "recipient_id" has_many :children, :class_name => "Message", :foreign_key => "parent_id" belongs_to :thread, :class_name => "Message", :foreign_key => "parent_id" end class MessagesController < ApplicationController def inbox @messages = current_user.received_messages.paginate :page => params[:page], :per_page => 10, :order => "created_at DESC" end end That gives me all the messages, but for one thread the thread itself and the most recent message will appear (and not only the most recent message). I can also not use the GROUP BY clause, because for the thread itself (the parent so to say) the parent_id = nil of course. Anyone got an idea on how to solve this in an elegant way? I already thought about adding the parent_id to the parent itself and then group by parent_id, but I'm not sure if that works. Thanks

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