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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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  • 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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  • Php fetch rows from multiple MySQL tables

    - by Jon McIntosh
    Right now I am fetching all of the rows from one of my tables: query = "SELECT * FROM thread WHERE threadid = 2 ORDER BY threadid DESC"; $result = mysql_query($query); $num_rows = mysql_num_rows($result); if((!is_bool($result) || $result) && $num_rows) { while($row = mysql_fetch_array($result)) { $thread = $row['title']; $threadID = $row['threadid']; $poster = $row['postusername']; } What I want to do is go to another table on my database: "post_display", and get the row 'text' where the threadid = 2.

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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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  • do's and don'ts for writing mysql queries

    - by nik
    One thing I always wonder while writing query is that am I writing most optimized query or not? I know certain things like: 1) using SELECT field1, filed2 instead of SELECT * 2) Giving proper indexes to the tables but I am sure there are more things that should be kept in mind for writing queries, since most of the database can only grow more and optimal query will help gr8 in execution time, Can u share some tips and tricks on writing queries?

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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 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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  • double left MYSQL join?

    - by Haroldo
    I've been trying left joins but as there are 2 joins, i think the problem is the 2nd join roots from table_B not table_A. i am not getting any results where there is the required data in the db. I am not getting a query error the query (simplified) SELECT events.*, ven.*, events_genres.* FROM events LEFT JOIN ven //OPTIONAL JOIN ON events.ven_id = ven.ven_id //OPTIONAL JOIN LEFT JOIN events_genres //REQUIRED JOIN ON events.event_id = events_genres.event_id //REQUIRED JOIN WHERE events.date >= '$this->now' AND WHERE events_genres.g_id = $g_id //REQUIRED MATCH ORDER BY date ven = optional, i'll have the info if its there. events_genres = required, i dont want any results that do not have a genre

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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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  • MySQL database design question

    - by Greelmo
    I'm trying to weigh the pros and cons of a database design, and would like to get some feedback as to the best approach. Here is the situation: I have users of my system that have only a few required items (username, password). They can then supply a lot of optional information. This optional information continues to grow as the system grows, so I want to do it in such a way that adding new optional information is easy. Currently, I have a separate table for each piece of information. For example, there's a table called 'names' that holds 'user_id', 'first_name', and 'last_name'. There's 'address', 'occupation', etc. You get the drift. In most cases, when I talk to my database, I'm looking only for users with one particular qualifier (name, address, etc.). However, there are instances when I want to see what information a user has set. The 'edit account' page, for example, must run queries for each piece of information it wants. Is this wasteful? Is there a way I can structure my queries or my database to make it so I never have to do one query for each piece of information like that without getting my tables to huge? If i want to add 'marital status', how hard will that be if I don't have a one-table-per-attribute system? Thanks in advance.

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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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  • Help with MySQL Query using CASE statement

    - by hairdresser-101
    I am trying to group a number of customers together based on their "Head Office" or "Parent" location. THis works ok except for a flaw which I didn't forsee when I was developing my system... For customers that did not have a "Parent" (standalone business) I defaulted the parent_id to 0. Therefore, my data would look like this: id parent_id customer 1 0 CustName#1 2 4 CustName#2 - Melbourne 3 4 CustName#2 - Sydney 4 0 CustName#2 (Head Office) What I want to do is Group my results together so that I have one row for CustName#1 and one row for CustName#2 BUT my problem is that there is no parent record for parent_id=0 and these rows are being excluded when using an inner join. I've tried using a case statement but that is not working either (parents are still being ignored) Any help would be greatly appreciated. Here is my query (My CASE is basically trying to get the business_name from the customer table based on the parent_id EXCEPT when the parent_id = 0, THEN just use the customer_name that is listed in the job_summary table): SELECT js.month_of_year, (CASE js.parent_id WHEN 0 THEN js.customer_name ELSE c.business_name END) as customer, SUM(js.jobs), SUM(js.total_cost), sum(js.total_sell) FROM JOB_SUMMARY js INNER JOIN customer c on js.parent_id=c.id group by js.month_of_year, (CASE c.parent_id WHEN 0 THEN js.customer_name ELSE c.business_name END) ORDER BY `customer` ASC

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  • mysql join Two tables to get records

    - by Saranya
    Hai guys, I have two tables Incharge and property. My property table has three fields 1stIncharge,2ndIncharge and 3rdIncharge. InchargeId is set as foreign key for all the above fields in the property table.. How to write a select statement that joins both the table.. I ve tried a bit but no result select P.Id,P.Name,P.1stIncharge,P.2ndIncharge,P.3rdIncharge,I.Id from Property as P join Incharge as I where (\\How to give condition here \\) Guys 3 fields P.1stIncharge, P.2ndIncharge, P.3rdIncharge has foreign key I.Id Edit: select P.Id,P.Name,P.1stIncharge,P.2ndIncharge,P.3rdIncharge,I1.Id from Property as P inner join Incharge as I1 on I1.Id=P.1stIncharge inner join Incharge as I2 on I2.Id=P.2ndIncharge inner join Incharge as I3 on I3.Id=P.3rdIncharge and this query working

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  • MySQL: updating a row and deleting the original in case it becomes a duplicate

    - by Silvio Donnini
    I have a simple table made up of two columns: col_A and col_B. The primary key is defined over both. I need to update some rows and assign to col_A values that may generate duplicates, for example: UPDATE `table` SET `col_A` = 66 WHERE `col_B` = 70 This statement sometimes yields a duplicate key error. I don't want to simply ignore the error with UPDATE IGNORE, because then the rows that generate the error would remain unchanged. Instead, I want them to be deleted when they would conflict with another row after they have been updated I'd like to write something like: UPDATE `table` SET `col_A` = 66 WHERE `col_B` = 70 ON DUPLICATE KEY REPLACE which unfortunately isn't legal in SQL, so I need help finding another way around. Also, I'm using PHP and could consider a hybrid solution (i.e. part query part php code), but keep in mind that I have to perform this updating operation many millions of times. thanks for your attention, Silvio Reminder: UPDATE's syntax has problems with joins with the same table that is being updated

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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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  • 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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  • Problem importing mysql triggers generated from mysqldump

    - by OM The Eternity
    I am using phpmyadmin for using the mysqldump query, but as per my requirement i have to create a new database which is clone of the previous one, now in this case when i import the main DB it contain all the trigger information as well with the DB name mentioned in it.. As i import this DB to new one my triggers get imported as well but the trigger_schema are not changed as per new DB.. What could be done to get resolve this problem?

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  • mysql dynamic cursor

    - by machaa
    Here is the procedure I wrote- Cursors c1 & c2. c2 is inside c1, I tried declaring c2 below c1 (outside the c1 cursor) but then I is NOT taking the updated value :( Any suggestions to make it working would be helpful, Thanks create table t1(i int); create table t2(i int, j int); insert into t1(i) values(1), (2), (3), (4), (5); insert into t2(i, j) values(1, 6), (2, 7), (3, 8), (4, 9), (5, 10); delimiter $ CREATE PROCEDURE p1() BEGIN DECLARE I INT; DECLARE J INT; DECLARE done INT DEFAULT 0; DECLARE c1 CURSOR FOR SELECT i FROM t1; DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1; OPEN c1; REPEAT FETCH c1 INTO I; IF NOT done THEN select I; DECLARE c2 CURSOR FOR SELECT j FROM t2 WHERE i = I; OPEN c2; REPEAT FETCH c2 into J; IF NOT done THEN SELECT J; END IF; UNTIL done END REPEAT; CLOSE c2; set done = 0; END IF; UNTIL done END REPEAT; CLOSE c1; END$ delimiter ;

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  • MySql left join on several regs

    - by egidiocs
    Hi there! I have this table1 idproduct(PK) | date_to_go 1 2010-01-18 2 2010-02-01 3 2010-02-21 4 2010-02-03 and this other table2 that controls date_to_go updates id | idproduct(FK) | prev_date_to_go | date_to_go | update_date 1 1 2010-01-01 2010-01-05 2009-12-01 2 1 2010-01-05 2010-01-10 2009-12-20 3 1 2010-01-10 2010-01-18 2009-12-20 4 3 2010-01-20 2010-02-03 2010-01-05 So, in this example, for table1.idproduct #1 2010-01-18 is the actual date_to_go and 2010-01-01 (table2.prev_date_to_go, first reg) is the original date_to_go . using this query select v.idproduct, v.date_to_go, p.prev_date_to_go original_date_to_go from table1 v left join produto_datas p on p.idproduto = v.idproduto group by (v.idproduto) order by v.idproduto can I assume that original_date_to_go will be the first related reg of table2? idproduct | date_to_go | original_date_to_go 1 2010-01-18 2010-01-01 2 2010-02-01 NULL 3 2010-02-21 2010-01-20 4 2010-02-03 NULL

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  • mysql order-by original "where order"

    - by Benjamin Dobnikar
    I have this order-by problem I canot crack. I select from my table like this: SELECT * FROM 'sidemodules' WHERE name = 'module1' OR name = 'module2' OR 'name3' Which returns me the modules I want. But the modules lie the table, say in this order: module3 module1 module2 And they are returned to me in this order. How can I get them to display in order AS IN THE WHERE CLAUSE (1,2,3) ? Big thanks!

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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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  • 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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  • mySQL not saving data?

    - by tony noriega
    i have a PHP contact form that submits data, and an email...: <?php $dbh=mysql_connect ("localhost", "username", "password") or die ('I cannot connect to the database because: ' . mysql_error()); mysql_select_db ("guest"); if (isset($_POST['submit'])) { if (!$_POST['name'] | !$_POST['email']) { echo"<div class='error'>Error<br />Please provide your Name and Email Address so we may properly contact you.</div>"; } else { $age = $_POST['age']; $name = $_POST['name']; $gender = $_POST['gender']; $email = $_POST['email']; $phone = $_POST['phone']; $comments = $_POST['comments']; $query = "INSERT INTO contact_us (age,name,gender,email,phone,comments) VALUES ('$age','$name','$gender','$email','$phone','$comments')"; mysql_query($query); mysql_close(); $yoursite = "Mysite "; $youremail = $email; $subject = "Website Guest Contact Us Form"; $message = "$name would like you to contact them Contact PH: $phone Email: $email Age: $age Gender: $gender Comments: $comments"; $email2 = "[email protected]"; mail($email2, $subject, $message, "From: $email"); echo"<div class='thankyou'>Thank you for contacting us,<br /> we will respond as soon as we can.</div>"; } } ?> The email is coming through fine, but the data is not storing the dbase... am i missing something? Its the same script as i use on another contact us page, only difference is instead of parsing the data on teh same page, i now send this data to a "thankyou.php" page... i tried changing $_POST to $_GET but that killed the page... what am i doing wrong?

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