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• MySQL - Calculating fields on the fly vs storing calculated data

  - by Christian Varga

  Hi Everyone, I apologise if this has been asked before, but I can't seem to find an answer to a question that I have about calculating on the fly vs storing fields in a database. I read a few articles that suggested it was preferable to calculate when you can, but I would just like to know if that still applies to the following 2 examples. Example 1. Say you are storing data relating to a car. You store the fuel tank size in litres, and how many litres it uses per 100km. You also want to know how many KMs it can travel, which can be calculated from the tank size and economy. I see 2 ways of doing this: When a car is added or updated, calculate the amount of KMs and store this as a static field in the database. Every time a car is accessed, calculate the amount of KMs on the fly. Because the cars economy/tank size doesn't change (although it could be edited), the KMs is a pretty static value. I don't see why we would calculate it every single time the car is accessed. Wouldn't this waste cpu time as opposed to simply storing it in a separate field in the database and calculating only when a car is added or updated? My next example, which is almost an entirely different question (but on the same topic), relates to counting children. Let's say we have a app which has categories and items. We have a view where we display all the categories, and a count of all the items inside each category. Again, I'm wondering what's better. To perform a MySQL query to count all the items in each category every single time the page is accessed? Or store the count in a field in the categories table and update when an item is added / deleted? I know it is redundant to store anything that can be calculated, but I worry that calculating fields or counting records might be slow as opposed to storing the data in a field. If it's not then please let me know, I just want to learn about when to use either method. On a small scale I guess it wouldn't matter either way, but apps like Facebook, would they really count the amount of friends you have every time someone views your profile or would they just store it as a field? I'd appreciate any responses to both of these scenarios, and any resource that might explain the benefits of calculating vs storing. Thanks in advance, Christian

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• check_ssh executed from Nagios server returns "Server answer: ", nothing else

  - by phs

  Commmand works on the host I need to monitor (its IP is denoted as $HOSTADDRESS$ here): [root@host ~]# /usr/local/nagios/libexec/check_ssh localhost SSH OK - OpenSSH_4.3 (protocol 2.0) However, on the Nagios server, it does not: root@server:~# /usr/lib/nagios/plugins/check_ssh -H $HOSTADDRESS$ Server answer: I can see that the port is open: root@server:~# /usr/lib/nagios/plugins/check_tcp -H $HOSTADDRESS$ -p 22 TCP OK - 0.123 second response time on port 22|time=0.123277s;;;0.000000;10.000000 And I can verify with telnet: root@server:/etc/nagios3/conf.d# telnet $HOSTADDRESS$ 22 Trying $HOSTADDRESS$... Connected to $HOSTADDRESS$. Escape character is '^]'. After searching the web for two hours and trying different suggestions I am out of ideas. I have several other hosts with similar setup, and they don't have this problem. I have compared the configs and they look the same (I think). I am clearly missing something here.

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• June 2013 release of SSDT contains a minor bug that you should be aware of

  - by jamiet

  I have discovered what seems, to me, like a bug in the June 2013 release of SSDT and given the problems that it created yesterday on my current gig I thought it prudent to write this blog post to inform people of it. I’ve built a very simple SSDT project to reproduce the problem that has just two tables, [Table1] and [Table2], and also a procedure [Procedure1]: The two tables have exactly the same definition, both a have a single column called [Id] of type integer. CREATE TABLE [dbo].[Table1] (     [Id] INT NOT NULL PRIMARY KEY ) My stored procedure simply joins the two together, orders them by the column used in the join predicate, and returns the results: CREATE PROCEDURE [dbo].[Procedure1] AS     SELECT t1.*     FROM    Table1 t1     INNER JOIN Table2 t2         ON    t1.Id = t2.Id     ORDER BY Id Now if I create those three objects manually and then execute the stored procedure, it works fine: So we know that the code works. Unfortunately, SSDT thinks that there is an error here: The text of that error is: Procedure: [dbo].[Procedure1] contains an unresolved reference to an object. Either the object does not exist or the reference is ambiguous because it could refer to any of the following objects: [dbo].[Table1].[Id] or [dbo].[Table2].[Id]. Its complaining that the [Id] field in the ORDER BY clause is ambiguous. Now you may well be thinking at this point “OK, just stick a table alias into the ORDER BY predicate and everything will be fine!” Well that’s true, but there’s a bigger problem here. One of the developers at my current client installed this drop of SSDT and all of a sudden all the builds started failing on his machine – he had errors left right and centre because, as it transpires, we have a fair bit of code that exhibits this scenario.  Worse, previous installations of SSDT do not flag this code as erroneous and therein lies the rub. We immediately had a mass panic where we had to run around the department to our developers (of which there are many) ensuring that none of them should upgrade their SSDT installation if they wanted to carry on being productive for the rest of the day. Also bear in mind that as soon as a new drop of SSDT comes out then the previous version is instantly unavailable so rolling back is going to be impossible unless you have created an administrative install of SSDT for that previous version. Just thought you should know! In the grand schema of things this isn’t a big deal as the bug can be worked around with a simple code modification but forewarned is forearmed so they say! Last thing to say, if you want to know which version of SSDT you are running check my blog post Which version of SSDT Database Projects do I have installed? @Jamiet

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• Get current updated column name to use in a trigger

  - by Serge

  Is there a way to actually get the column name that was updated in order to use it in a trigger? Basically I'm trying to have an audit trail whenever a user inserts or updates a table (in this case it has to do with a Contact table) CREATE TRIGGER `after_update_contact` AFTER UPDATE ON `contact` FOR EACH ROW BEGIN INSERT INTO user_audit (id_user, even_date, table_name, record_id, field_name, old_value, new_value) VALUES (NEW.updatedby, NEW.lastUpdate, 'contact', NEW.id_contact, [...]) END How can I get the name of the column that's been updated and from that get the OLD and NEW values of that column. If multiple columns have been updated in a row or even multiple rows would it be possible to have an audit for each update?

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• How does the where clause in My SQl Work ?

  - by Eternal Learner

  Hi All, I have a doubt. Assume R and S are 2 relations with attributes A and B respectively . If I have a query Select * From R, S Where R.A = S.B Does this work like a double For Loop in say c or c++ For( i=0; i<n; i++) For( j=0; j<n; j++) if (i == j) //DO some work

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• php connecting to mysql server(localhost) very slow

  - by Ahmad

  actually its little complicated: summary: the connection to DB is very slow. the page rendering takes around 10 seconds but the last statement on the page is an echo and i can see its output while the page is loading in firefox (IE is same). in google chrome the output becomes visible only when the loading finishes. loading time is approximately the same across browsers. on debugging i found out that its the DB connectivity that is creating problem. the DB was on another machine. to debug further. i deployed the DB on my local machine .. so now the DB connection is at 127.0.0.1 but the connectivity still takes long time. this means that the issue is with APACHE/PHP and not with mysql. but then i deployed my code on another machine which connects to DB remotely.and everything seems fine. basically the application uses couple of mod_rewrite.. but i removed all the .htaccess files and the slow connectivity issue remains.. i installed another APACHE on my machine and used default settings. the connection was still very slow. i added following statements to measure the execution time $stime = microtime(); $stime = explode(" ",$stime); $stime = $stime[1] + $stime[0]; // my code -- it involves connection to DB $mtime = microtime(); $mtime = explode(" ",$mtime); $mtime = $mtime[1] + $mtime[0]; $totaltime = ($mtime - $stime); echo $totaltime; the output is 0.0631899833679 but firebug Net panel shows total loading time of 10-11 seconds. same is the case with google chrome i tried to turn off windows firewall.. connectivity is still slow and i just can't quite find the reason.. i've tried multiple DB servers.. multiple apaches.. nothing seems to be working.. any idea of what might be the problem?

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• SQL for total count and count within that where condition is true

  - by twmulloy

  Hello, I have a single user table and I'm trying to come up with a query that returns the total count of all users grouped by date along with the total count of users grouped by date who are of a specific client. Here is what I have thus far, where there's the total count of users grouped by date, but can't seem to figure out how to get the count of those users where user.client_id = x SELECT user.created, COUNT(user.id) AS overall_count FROM user GROUP BY DATE(user.created) trying for a row result like this: [created] => 2010-05-15 19:59:30 [overall_count] => 10 [client_count] => (some fraction of overall count, the number of users where user.client_id = x grouped by date)

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• Parsing CSV File to MySQL DB in PHP

  - by Austin

  I have a some 350-lined CSV File with all sorts of vendors that fall into Clothes, Tools, Entertainment, etc.. categories. Using the following code I have been able to print out my CSV File. <?php $fp = fopen('promo_catalog_expanded.csv', 'r'); echo '<tr><td>'; echo implode('</td><td>', fgetcsv($fp, 4096, ',')); echo '</td></tr>'; while(!feof($fp)) { list($cat, $var, $name, $var2, $web, $var3, $phone,$var4, $kw,$var5, $desc) = fgetcsv($fp, 4096); echo '<tr><td>'; echo $cat. '</td><td>' . $name . '</td><td><a href="http://www.' . $web .'" target="_blank">' .$web.'</a></td><td>'.$phone.'</td><td>'.$kw.'</td><td>'.$desc.'</td>' ; echo '</td></tr>'; } fclose($file_handle); show_source(__FILE__); ?> First thing you will probably notice is the extraneous vars within the list(). this is because of how the excel spreadsheet/csv file: Category,,Company Name,,Website,,Phone,,Keywords,,Description ,,,,,,,,,, Clothes,,4imprint,,4imprint.com,,877-466-7746,,"polos, jackets, coats, workwear, sweatshirts, hoodies, long sleeve, pullovers, t-shirts, tees, tshirts,",,An embroidery and apparel company based in Wisconsin. ,,Apollo Embroidery,,apolloemb.com,,1-800-982-2146,,"hats, caps, headwear, bags, totes, backpacks, blankets, embroidery",,An embroidery sales company based in California. One thing to note is that the last line starts with two commas as it is also listed within "Clothes" category. My concern is that I am going about the CSV output wrong. Should I be using a foreach loop instead of this list way? Should I first get rid of any unnecessary blank columns? Please advise any flaws you may find, improvements I can use so I can be ready to import this data to a MySQL DB.

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• inserting array into database table in single query

  - by Praveen Prasad

  iam having an array of items like [item1,itmem2,item3]; i have to insert these items at a particular userId: final results look like this UserId ItemId 2 || item1 2 || item2 2 || item3 currently iam looping through the array in php code and inserting each item one by one eg foreach($items as $item) { insert into items (UserId,ItemId) value (2,$item); } is it possible i can insert all entries in single query.

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• Optimising (My)SQL Query

  - by Simon

  I usually use ORM instead of SQL and I am slightly out of touch on the different JOINs... SELECT `order_invoice`.*, `client`.*, `order_product`.*, SUM(product.cost) as net FROM `order_invoice` LEFT JOIN `client` ON order_invoice.client_id = client.client_id LEFT JOIN `order_product` ON order_invoice.invoice_id = order_product.invoice_id LEFT JOIN `product` ON order_product.product_id = product.product_id WHERE (order_invoice.date_created >= '2009-01-01') AND (order_invoice.date_created <= '2009-02-01') GROUP BY `order_invoice`.`invoice_id` The tables/ columns are logically names... it's an shop type application... the query works... it's just very very slow... I use the Zend Framework and would usually use Zend_Db_Table_Row::find(Parent|Dependent)Row(set)('TableClass') but I have to make lots of joins and I thought it'll improve performance by doing it all in one query instead of hundreds... Can I improve the above query by using more appropriate JOINs or a different implementation? Many thanks.

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• Java: Making concurrent MySQL queries from multiple clients synchronised

  - by Misha Gale

  I work at a gaming cybercafe, and we've got a system here (smartlaunch) which keeps track of game licenses. I've written a program which interfaces with this system (actually, with it's backend MySQL database). The program is meant to be run on a client PC and (1) query the database to select an unused license from the pool available, then (2) mark this license as in use by the client PC. The problem is, I've got a concurrency bug. The program is meant to be launched simultaneously on multiple machines, and when this happens, some machines often try and acquire the same license. I think that this is because steps (1) and (2) are not synchronised, i.e. one program determines that license #5 is available and selects it, but before it can mark #5 as in use another copy of the program on another PC tries to grab that same license. I've tried to solve this problem by using transactions and table locking, but it doesn't seem to make any difference - Am I doing this right? Here follows the code in question: public LicenseKey Acquire() throws SmartLaunchException, SQLException { Connection conn = SmartLaunchDB.getConnection(); int PCID = SmartLaunchDB.getCurrentPCID(); conn.createStatement().execute("LOCK TABLE `licensekeys` WRITE"); String sql = "SELECT * FROM `licensekeys` WHERE `InUseByPC` = 0 AND LicenseSetupID = ? ORDER BY `ID` DESC LIMIT 1"; PreparedStatement statement = conn.prepareStatement(sql); statement.setInt(1, this.id); ResultSet results = statement.executeQuery(); if (results.next()) { int licenseID = results.getInt("ID"); sql = "UPDATE `licensekeys` SET `InUseByPC` = ? WHERE `ID` = ?"; statement = conn.prepareStatement(sql); statement.setInt(1, PCID); statement.setInt(2, licenseID); statement.executeUpdate(); statement.close(); conn.commit(); conn.createStatement().execute("UNLOCK TABLES"); return new LicenseKey(results.getInt("ID"), this, results.getString("LicenseKey"), results.getInt("LicenseKeyType")); } else { throw new SmartLaunchException("All licenses of type " + this.name + "are in use"); } }

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• how to tackle a custom forms database

  - by Neil Hickman

  I'm currently researching a project for the place that I work in. We are trying to create a system that will allow forms to be set up dynamically from a database. My question is what database structure would best suit something like this? I currently have a structure of: forms_form forms_formfields forms_formdata I don't think this is the most appropriate layout for this. Basically to make is make sense I need to be able to make a form within the database that can have infinite fields all customized and have the data when submitted stored in the database.

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• Help with SQL query (Calculate a ratio between two entitiess)

  - by Mestika

  Hi, I’m going to calculate a ratio between two entities but are having some trouble with the query. The principal is the same to, say a forum, where you say: A user gets points for every new thread. Then, calculate the ratio of points for the number of threads. Example: User A has 300 points. User A has started 6 thread. The point ratio is: 50:6 My schemas look as following: student(studentid, name, class, major) course(courseid, coursename, department) courseoffering(courseid, semester, year, instructor) faculty(name, office, salary) gradereport(studentid, courseid, semester, year, grade) The relations is a following: Faculity(name) = courseoffering(instructor) Student(studentid) = gradereport (studentid) Courseoffering(courseid) = course(courseid) Gradereport(courseid) = courseoffering(courseid) I have this query to select the faculty names there is teaching one or more students: SELECT COUNT(faculty.name) FROM faculty, courseoffering, gradereport, student WHERE faculty.name = courseoffering.instructor AND courseoffering.courseid = gradereport.courseid AND gradereport.studentid = student.studentid My problem is to find the ratio between the faculty members salary in regarding to the number of students they are teaching. Say, a teacher get 10.000 in salary and teaches 5 students, then his ratio should be 1:5. I hope that someone has an answer to my problem and understand what I'm having trouble with. Thanks Mestika

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• How can get unique values from data table using dql?

  - by piemesons

  I am having a table in which there is a column in which various values are stored.i want to retrieve unique values from that table using dql. Doctrine_Query::create() ->select('rec.school') ->from('Records rec') ->where("rec.city='$city' ") ->execute(); Now i want only unique values. Can anybody tell me how to do that... Edit Table Structure: CREATE TABLE IF NOT EXISTS `records` ( `id` int(11) NOT NULL AUTO_INCREMENT, `state` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL, `city` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL, `school` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci AUTO_INCREMENT=16334 ; This is the Query I am using: Doctrine_Query::create() ->select('DISTINCT rec.city') ->from('Records rec') ->where("rec.state = '$state'") // ->getSql(); ->execute(); Generting Sql for this gives me: SELECT DISTINCT r.id AS r__id, r.city AS r__city FROM records r WHERE r.state = 'AR' Now check the sql generated:::: DISTINCT is on 'id' column where as i want Distinct on city column. Anybody know how to fix this. EDIT2 Id is unique cause its an auto incremental value.Ya i have some real duplicates in city column like: Delhi and Delhi. Right.. Now when i am trying to fetch data from it, I am getting Delhi two times. How can i make query like this: select DISTINCT rec.city where state="xyz"; Cause this will give me the proper output. EDIT3: Anybody who can tell me how to figure out this query..???

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• How do I re-create a MySQL InnoDB table from an .ibd file?

  - by knorv

  Assume that the following MySQL files have been restored from a backup tape: tablename.frm tablename.ibd Furthermore, assume that the MySQL installation was running with innodb_file_per_table and that the database was cleanly shutdown with mysqladmin shutdown. Given a fresh install of the same MySQL version that the restored MySQL files were taken from, how do I import the data from tablename.ibd/tablename.frm into this new install?

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• block write access to table from an application in mysql

  - by hoberion

  Hello, We have a CMS plugin that writes statistics to 1 table, this creates performance issues on the entire platform. We decided to use another statistics plugin which can connect to a different database server (the first plugin couldn't!) however we need parts of the first plugin. I want to lock the statistics table to prevent misusage (not allowed to drop it by the developer) So I was wondering if a lock table could do this or if I can implement some sort of read only table

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• ASP.Net / MySQL : Translating content into several languages

  - by philwilks

  I have an ASP.Net website which uses a MySQL database for the back end. The website is an English e-commerce system, and we are looking at the possibility of translating it into about five other languages (French, Spanish etc). We will be getting human translators to perform the translation - we've looked at automated services but these aren't good enough. The static text on the site (e.g. headings, buttons etc) can easily be served up in multiple languages via .Net's built in localization features (resx files etc). The thing that I'm not so sure about it how best to store and retrieve the multi-language content in the database. For example, there is a products table that includes these fields... productId (int) categoryId (int) title (varchar) summary (varchar) description (text) features (text) The title, summary, description and features text would need to be available in all the different languages. Here are the two options that I've come up with... Create additional field for each language For example we could have titleEn, titleFr, titleEs etc for all the languages, and repeat this for all text columns. We would then adapt our code to use the appropriate field depending on the language selected. This feels a bit hacky, and also would lead to some very large tables. Also, if we wanted to add additional languages in the future it would be time consuming to add even more columns. Use a lookup table We could create a new table with the following format... textId | languageId | content ------------------------------- 10 | EN | Car 10 | FR | Voiture 10 | ES | Coche 11 | EN | Bike 11 | FR | Vélo We'd then adapt our products table to reference the appropriate textId for the title, summary, description and features instead of having the text stored in the product table. This seems much more elegant, but I can't think of a simple way of getting this data out of the database and onto the page without using complex SQL statements. Of course adding new languages in the future would be very simple compared to the previous option. I'd be very grateful for any suggestions about the best way to achieve this! Is there any "best practice" guidance out there? Has anyone done this before?

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• $query returns results but not the ones i want: $query looks good to me :S

  - by Toni Michel Caubet

  I'll start again, Lets say My data is: Table element (id,name,....) 1, name element 1, .... 2, name element 2, .... 3, name element 3, .... Table tags (id,name,id_element, ....) 1, happy , 1 2, result, 1 3, very , 1 4, element, 2 5, another, 3 6, element, 1 7, happy, 2 So if search is 'very, happy,element,result': Results i would like 1) element with id = 2 because it has all tags 2) element with id = 1 because it has the tag 'element' and the tag 'happy' (only 2 less taggs) 3) .... (only 3 less taggs) So if search is 'happy,element': Results i would like 1) element with id = 1 because it has all tags (and no more) 2) element with id = 2 because it has the tag 'element' and the tag 'happy' (and two more tags) 3) .... and 3 more tags This is an echo to my query: (it doesn't fit al requirements i wrote, but its first test to find with matched tags) SELECT element.id as id_deseada,tagg.* FROM element,tagg WHERE tagg.id_element = element.id AND tagg.nombre IN ('happy','tagg','result') GROUP BY tagg.id_element ORDER BY element.votos This returns 10 duplicated elements... :S and doen't even have all taggs (and on database there are taggs with 'happy' results) if it helps, thats how i get the elements of a tag (by name and with only one tagg) $query = "SELECT element.id FROM element,tagg WHERE tagg.nombre = '$nombre_tagg' AND tagg.id_element = element.id AND lan = '$lan' GROUP BY tagg.id_element"; I hope it's a bit easier to understand now, excuse my english.. :) Thanks a lot for you possible aportation!

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• Need help with a SELECT statement

  - by Travis

  I express the relationship between records and searchtags that can be attached to records like so: TABLE RECORDS id name TABLE SEARCHTAGS id recordid name I want to be able to SELECT records based on the searchtags that they have. For example, I want to be able to SELECT all records that have searchtags: (1 OR 2 OR 5) AND (6 OR 7) AND (10) Using the above data structure, I am uncertain how to structure the SQL to accomplish this. Any suggestions? Thanks!

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• How can i rewrite this query for faster execution

  - by sam

  SELECT s1.ID FROM binventory_ostemp s1 JOIN ( SELECT Cust_FkId, ProcessID, MAX(Service_Duration) AS duration FROM binventory_ostemp WHERE ProcessID='4d2d6068678bc' AND Overall_Rank IN ( SELECT MIN(Overall_Rank) FROM binventory_ostemp WHERE ProcessID='4d2d6068678bc' GROUP BY Cust_FkId ) GROUP BY Cust_FkId ) AS s2 ON s1.Cust_FkId = s2.Cust_FkId AND s1.ProcessID=s2.ProcessID AND s1.Service_Duration=s2.duration AND s1.ProcessID='4d2d6068678bc' GROUP BY s1.Cust_FkId It just goes away if there are more than 10K rows in that table. What it does is find rows for each customer who has min. of overall rank and in those max. of service duration for a given processid Table Data ID Cust_FkId Overall_Rank Service_Duration ProcessID 1 23 2 30 4d2d6068678bc 2 23 1 45 4d2d6068678bc 3 23 1 60 4d2d6068678bc 4 56 3 90 4d2d6068678bc 5 56 2 50 4d2d6068678bc 6 56 2 85 4d2d6068678bc

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• How to create wordpress-like option table and get values for each row?

  - by Nacho

  Hi guys. I'm looking to create an options table in my db that makes every record a system option, so I can work with a little number of fields. My db has the following structure: 3 columns named id, name, and value The following data is inserted as an example: +--+-----------+--------------------------+ |id|name |value | +--+-----------+--------------------------+ | 1|uri |www.example.com | | 2|sitename |Working it out | | 3|base_folder|/folder1/folder2/ | | 4|slogan |Just a slogan for the site| +--+-----------+--------------------------+ That way I can include a large number of customizable system options very easily. The problem is that I don't know how to retrieve them. How do I get the value of uri and store it as a var? And better yet, how do I get, for exmaple, values of id 1 and 4 only without making a query each time? (I assume multiple queries are useless and a pretty ugly method.) I know the question is pretty basic but I'm lost here. I'd really appreciate your answer!

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• Write a SQL to meet my requirement.

  - by rgksugan

  I have been trying to solve this problem for a lot of days. But wouldn't. Please help me. I need a SQL to list product_code, product_name, qty_sold, last_order_date for all the products that have been sold within a date range sorted by the number of quantity sold. My Table structure: tbl_product(product_id,product_code,product_name) tbl_order_detail(order_item_id,order_id,product_id,quantity) tbl_order(order_id,order_date)

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• Configuring weblogic server console with external server urls, etc

  - by MeBigFatGuy

  there are obviously various 'canned' configuration options in oracle's weblogic server console for setting up data sources, jms queues, ldap servers etc, etc. What i want however is a way to configure other servers, mostly server urls, etc, in the console as well, and allow web applications running on the web server to access those configuration settings at runtime, probably through jndi names. Things like a document management server, a workflow server, etc. However I'm at a loss for how to configure custom jndi 'data sources' within wls' console. Is this possible?

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• Table alias -- Unkown column in field list

  - by Jason

  Hi all, I have a sql query which is executing a LEFT JOIN on 2 tables in which some of the columns are ambiguous. I can prefix the joined tables but when I try to prefix one of the columns from the table in the FROM clause, it tells me Unknown column. I even tried giving that table an alias like so ...From points AS p and using "p" to prefix the tables but that didn't work either. Can someone tell me what I'm doing wrong. Here is my query: SELECT point_title, point_url, address, city, state, zip_code, phone, `points`.`lat`, `points`.`longi`, featured, kmlno, image_url, category.title, category_id, point_id, lat, longi, reviews.star_points, reviews.review_id, count(reviews.point_id) as totals FROM (SELECT *, ( 3959 * acos( cos( radians('37.7717185') ) * cos( radians( lat ) ) * cos( radians( longi ) - radians('-122.4438929') ) + sin( radians('37.7717185') ) * sin( radians( lat ) ) ) ) AS distance FROM points HAVING distance < '25') as distResults LEFT JOIN category USING ( category_id ) LEFT JOIN reviews USING ( point_id ) WHERE (point_title LIKE '%Playgrounds%' OR category.title LIKE '%Playgrounds%') GROUP BY point_id ORDER BY totals DESC, distance LIMIT 0 , 10

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• how to diffrentiate between same field names of two tables in a select query??

  - by developer

  i have more than two tables in my database and all of them contains same field names like table A table B table C field1 field1 field1 field2 field2 field2 field3 field3 field3 . . . . . . . . . . . . I have to write a SELECT query which gets almost all same fields from these 3 tables.Iam using something like this :- select a.field1,a.field2,a.field3,b.field1,b.field2,b.field3,c.field1,c.field2,c.field3 from table A as a, table B as b,table C as c where so and so. but when i print field1's value it gives me the last table values. How can i get all the values of three tables with the same field names??? do i have to write individual query for every table OR there is any ways of fetching them all in a single query????

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