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• Rails running multiple delayed_job - lock tables

  - by pepernik

  Hey. I use delayed_job for background processing. I have 8 CPU server, MySQL and I start 7 delayed_job processes RAILS_ENV=production script/delayed_job -n 7 start Q1: I'm wondering is it possible that 2 or more delayed_job processes start processing the same process (the same record-row in the database delayed_jobs). I checked the code of the delayed_job plugin but can not find the lock directive in a way it should be. I think each process should lock the database table before executing an UPDATE on lock_by column. They lock the record simply by updating the locked_by field (UPDATE delayed_jobs SET locked_by...). Is that really enough? No locking needed? Why? I know that UPDATE has higher priority than SELECT but I think this does not have the effect in this case. My understanding of the multy-threaded situation is: Process1: Get waiting job X. [OK] Process2: Get waiting jobs X. [OK] Process1: Update locked_by field. [OK] Process2: Update locked_by field. [OK] Process1: Get waiting job X. [Already processed] Process2: Get waiting jobs X. [Already processed] I think in some cases more jobs can get the same information and can start processing the same process. Q2: Is 7 delayed_jobs a good number for 8CPU server? Why yes/not. Thx 10x!

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• has_many :through when join table doesn't contain FK to both tables

  - by seth.vargo

  I have a structure that isn't really a has_many :through example, but I'd like it to behave like one: # user.rb belongs_to :blog has_many :posts # post.rb belongs_to :user # blog.rb has_many :users has_many :posts, :through => :users # this obviously doesn't work becase # both FKs aren't in the blogs table I want to get ALL posts for a blog in an array. I'm aware that I can do this with Ruby using each or getting fancy with collect, but I'd like to let SQL do the work. Can someone explain how I can set up my models in a way that lets me call @blog.posts using SQL, not Ruby? Edit: I know in SQL I can write something like: SELECT * FROM posts WHERE posts.user_id IN ( SELECT users.id FROM users WHERE users.blog_id = 7 ) which obviously shows two queries are needed. I don't think this is possible with a join, but I'm not totally sure. It's obvious that a subquery is needed, but how do I get rails to build that subquery with ARel instead of having to return and use Ruby to loop and collect and such?

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• Disable resizing tables in mozilla in design mode

  - by Anatoliy

  Is there a way to remove the attribute '_moz_resizing="true"' added by Firefox from to avoid giving user the possibility to resize table in design mode (when contentEditable=true).

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• select, delete & update from multible tables using a single query in mysql

  - by mewis

  for example i use following command to find a record SELECT users.mail FROM users WHERE users.uid = %s if found an match, then i should like to delete this record, and update in the same query an another table. i can solve this with 'joins' ?

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• Updating multiple tables with LinqToSql in one unit of work

  - by zsharp

  Table 1: int ID-a(pk) Table 2: int ID-a(pk), int ID-b(pk) Table 3: int ID-b(pk), string C I have the data to insert into Table 1. But I do not have the ID-a, which is autogenerated. I have many string C to insert in Table 3. I am trying to insert row into Table 1, get the ID-a to insert in Table 2 along with the ID-b that is auto-Generated in Table 3 when I submit each string C, all in one submission to db. Right now I am calling dc.SubmitChanges twice in same call. Is it efficient to have to submit changes twice on same DataContext or can this be combined further?

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• SQLAlchemy: select over multiple tables

  - by ahojnnes

  Hi, I wanted to optimize my database query: link_list = select( columns=[link_table.c.rating, link_table.c.url, link_table.c.donations_in], whereclause=and_( not_(link_table.c.id.in_( select( columns=[request_table.c.recipient], whereclause=request_table.c.donator==donator.id ).as_scalar() )), link_table.c.id!=donator.id, ), limit=20, ).execute().fetchall() and tried to merge those two selects in one query: link_list = select( columns=[link_table.c.rating, link_table.c.url, link_table.c.donations_in], whereclause=and_( link_table.c.active==True, link_table.c.id!=donator.id, request_table.c.donator==donator.id, link_table.c.id!=request_table.c.recipient, ), limit=20, order_by=[link_table.c.rating.desc()] ).execute().fetchall() the database-schema looks like: link_table = Table('links', metadata, Column('id', Integer, primary_key=True, autoincrement=True), Column('url', Unicode(250), index=True, unique=True), Column('registration_date', DateTime), Column('donations_in', Integer), Column('active', Boolean), ) request_table = Table('requests', metadata, Column('id', Integer, primary_key=True, autoincrement=True), Column('recipient', Integer, ForeignKey('links.id')), Column('donator', Integer, ForeignKey('links.id')), Column('date', DateTime), ) There are several links (donator) in request_table pointing to one link in the link_table. I want to have links from link_table, which are not yet "requested". But this does not work. Is it actually possible, what I'm trying to do? If so, how would you do that? Thank you very much in advance!

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• Localized tables and Entity Framework

  - by Pyttroll

  Hi all, I have a scenario where I need to localized values of objects in my database. Let's say you have an application that can create animals, if the user is english the value of the "Name" property of an animal would be entered as "Cat" in the UI whereas it would be entered as "Chat" in french. The animal culture table would contain 2 records pointing to the same animal in the parent table. When reading values back, if the value of "Name" does not exist in the user culture the default value (value the object was originally created with) would be used. The following diagrams demonstrate how the data is stored in SQL: I'm trying to map this schema to an object model using the Entity Framework, I'm a bit confused as to what the best way to approach the problem. Is EF appropriate for this? Should I used EF4? This EF model will be used by .NET RIA Services. Thanks, Pierre-Yves Troel Ayuda Media Systems http://www.ayudasystems.com

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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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• Single HTML Table from multiple MySQL tables

  - by David Chouinard

  Hi! I've been struggling for a while with this one; I'll try to explain it here as simply as possible. Consider this MySQL table: +----------+-----------+---------+--------+ |status_id |session_id |pilot_id |present | +----------+-----------+---------+--------+ |1 |61 |901 |1 | |2 |63 |901 |1 | |3 |62 |901 |0 | |4 |62 |902 |1 | |5 |63 |903 |1 | +----------+-----------+---------+--------+ Both session_id and pilot_id are foreign keys making reference to a primary key in another table. The same pilot_id can be associated with different session_id, but every pilot_id-session_id combination is unique. I need to make an HTML table (in PHP) that would display the data like this: +----------+---------+---------+---------+ | |61 |62 |63 | +----------+---------+---------+---------+ |901 |X | |X | |902 | |X | | |903 | | |X | +----------+---------+---------+---------+ Hence, rows are pilot_id and columns are session_id. When a pilot_id-session_id combination has a present value of 1, the corresponding cell should be checked. (ie. when the row-combination is zero or the combination does not exist in the MySQL table, nothing should appear in the HTML table) Phew. Any ideas? Thanks!

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• SQl to select from multiple tables

  - by SmartestVEGA

  I have two table emptable1(empid,status) emptable2(empid,week) i want to select all the empid whose status is 0 in emptable1 and from that list of empid i need to select empid whose week is 7 from the table emptable2 Please help :-)

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• Create fulltext index on a VIEW

  - by kylex

  Is it possible to create a full text index on a VIEW? If so, given two columns column1 and column2 on a VIEW, what is the SQL to get this done? The reason I'd like to do this is I have two very large tables, where I need to do a FULLTEXT search of a single column on each table and combine the results. The results need to be ordered as a single unit. Suggestions? EDIT: This was my attempt at creating a UNION and ordering by each statements scoring. (SELECT a_name AS name, MATCH(a_name) AGAINST('$keyword') as ascore FROM a WHERE MATCH a_name AGAINST('$keyword')) UNION (SELECT s_name AS name,MATCH(s_name) AGAINST('$keyword') as sscore FROM s WHERE MATCH s_name AGAINST('$keyword')) ORDER BY (ascore + sscore) ASC sscore was not recognized.

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• How to output JOINed tables?

  - by ilhan

  $id=(int)$_GET["id"]; $result = mysql_query("SELECT questionstable.*, categorytable.name FROM questionstable INNER JOIN categorytable ON categorytable.id = questionstable.category WHERE id=$id"); $row = mysql_fetch_assoc($result); Warning: mysql_fetch_assoc() expects parameter 1 to be resource, boolean given in C:\Program Files\EasyPHP-5.3.4.0\www\scsoru.php on line 33

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• problem in fetching data from several tables in one query

  - by Mac Taylor

  hey guys in an attempt to union my querries into one query to database , now im in need of geting username of first poster and last poster of a topic in my forums here is my code to do as i told :: $result = $db->sql_query("SELECT t.*,p.*,u.* SUM(t.topic_approved='1') AS Amount_Of_Topics, SUM(p.post_approved ='1') AS Amount_Of_Posts FROM bb3topics t, bb3posts p, bb3users u GROUP BY t.topic_last_post_id ORDER BY t.topic_last_post_id DESC LIMIT 10 " ); while( $row = $db->sql_fetchrow($result) ) { $Amount_Of_Topics = $row['Amount_Of_Topics']; $Amount_Of_Posts = $row['Amount_Of_Posts']; $Amount_Of_Topic_Replies = $Amount_Of_Topic_Replies + $row['topic_replies']; $Amount_Of_Topic_Views = $Amount_Of_Topic_Views + $row['topic_views']; $topic_id = $row['topic_id']; $forum_id = $row['forum_id']; $topic_last_post_id = $row['topic_last_post_id']; $topic_title = $row['topic_title']; $topic_poster = $row['topic_poster']; $topic_views = $row['topic_views']; $topic_replies = $row['topic_replies']; $topic_moved_id = $row['topic_moved_id']; $topic_time = $row['topic_time']; $result2 = $db->sql_query( "SELECT topic_id, poster_id, post_time FROM bb3posts where post_id = '$topic_last_post_id'" ); list( $topic_id, $poster_id, $post_time ) = $db->sql_fetchrow( $result2 ); $result3 = $db->sql_query( "SELECT username, user_id FROM bb3users where user_id='$poster_id'" ); list( $uname, $uid ) = $db->sql_fetchrow( $result3 ); $LastPoster = "$uname"; $result4 = $db->sql_query( "SELECT username, user_id FROM bb3users where user_id='$topic_poster'" ); list( $uname, $uid ) = $db->sql_fetchrow( $result4 ); $OrigPoster = "$uname"; now i need to query all this together not in separated ones i tried using left join but didn't worked what mysql conjunction should i use ?!

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• how to Compute the average probe length for success and failure - Linear probe (Hash Tables)

  - by fang_dejavu

  hi everyone, I'm doing an assignment for my Data Structures class. we were asked to to study linear probing with load factors of .1, .2 , .3, ...., and .9. The formula for testing is: The average probe length using linear probing is roughly Success-- ( 1 + 1/(1-L)**2)/2 or Failure-- (1+1(1-L))/2. we are required to find the theoretical using the formula above which I did(just plug the load factor in the formula), then we have to calculate the empirical (which I not quite sure how to do). here is the rest of the requirements **For each load factor, 10,000 randomly generated positive ints between 1 and 50000 (inclusive) will be inserted into a table of the "right" size, where "right" is strictly based upon the load factor you are testing. Repeats are allowed. Be sure that your formula for randomly generated ints is correct. There is a class called Random in java.util. USE it! After a table of the right (based upon L) size is loaded with 10,000 ints, do 100 searches of newly generated random ints from the range of 1 to 50000. Compute the average probe length for each of the two formulas and indicate the denominators used in each calculationSo, for example, each test for a .5 load would have a table of size approximately 20,000 (adjusted to be prime) and similarly each test for a .9 load would have a table of approximate size 10,000/.9 (again adjusted to be prime). The program should run displaying the various load factors tested, the average probe for each search (the two denominators used to compute the averages will add to 100), and the theoretical answers using the formula above. .** how do I calculate the empirical success?

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• CSS Make one row the width of another

  - by gav

  I'm sure this is a fairly common problem but I'm new to CSS so I'm not sure how it's done. I tried searching for the issue but sometimes it's tricky to get the right keywords. I have a table the width of which I want to be constrained by a specific row. My table css is as follows; table { border: 1px solid #ccc; width: auto; margin-left: auto; margin-right: auto; } I have one row which contains cells for which I want the width to autofit and two rows of prose which currently force the table to take 100% width. How do I constrain the latter to have at most the autofit width of the first row? If tables aren't the way to go and this should be pure css and divs, how do you get one class to adopt the fixed but unknown width of another? Thanks, Gav

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• SQL Server Constraints Across Tables

  - by chama

  I have a SQL Server database with an Apartment table (which has columns FloorNum and BuildingID) and an ApartmentBuilding table (with column NumFloors). Is there any way to set up a constraint (using the SQL Server UI) to check that Apartment.FloorNum is greater than ApartmentBuilding.NumFloors? I tried this: FloorNum > ApartmentBuilding.NumFloors but now I realize that I somehow have to join the columns on the BuildingID, but I have no idea how to do that within a constraint. Thanks for your help!

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• Arrays in database tables and normalization

  - by Ivan Petrov

  Hi! Is it smart to keep arrays in table columns? More precisely I am thinking of the following schema which to my understanding violates normalization: create table Permissions( GroupID int not null default(-1), CategoryID int not null default(-1), Permissions varchar(max) not null default(''), constraint PK_GroupCategory primary key clustered(GroupID,CategoryID) ); and this: create table Permissions( GroupID int not null default(-1), CategoryID int not null default(-1), PermissionID int not null default(-1), constraint PK_GroupCategory primary key clustered(GroupID,CategoryID) ); UPD: Forgot to mention, in the scope of this concrete question we will consider that the "fetch rows that have permission X" won't be performed, instead all the lookups will be made by GroupID and CategoryID only Thoughts? Thanks in advance!

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• Oracle DBMS_PROFILER only shows Anonymous in the results tables

  - by Greg Reynolds

  I am new to DBMS_PROFILER. All the examples I have seen use a simple top-level procedure to demonstrate the use of the profiler, and from there get all the line numbers etc. I deploy all code in packages, and I am having great difficulty getting my profile session to populate the plsql_profiler_units with useful data. Most of my runs look like this: RUNID RUN_COMMENT UNIT_OWNER UNIT_NAME SECS PERCEN ----- ----------- ----------- -------------- ------- ------ 5 Test <anonymous> <anonymous> .00 2.1 Profiler 5 Test <anonymous> <anonymous> .00 2.1 Profiler 5 Test <anonymous> <anonymous> .00 2.1 Profiler I have just embedded the calls to the dbms_profiler.start_profiler, flush_data and stop_profiler as per all the examples. The main difference is that my code is in a package, and calls in to other package. Do you have to profile every single stored procedure in your call stack? If so that makes this tool a little useless! I have checked http://www.dba-oracle.com/t_plsql_dbms_profiler.htm for hints, among other similar sites.

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• Querying Two Tables At Once

  - by John

  Hello, I am trying to do what I believe is called a join query. First, in a MySQL table called "login," I want to look up what "loginid" is in the record where "username" equals $profile. (This will be just one record / row in the MySQL table). Then, I want to take that "loginid" and look up all rows / records in a different MySQL table called "submission," and pull data that have that "loginid." This could possibly be more than one record / row. How do I do this? The code below doesn't seem to work. Thanks in advance, John $profile = mysql_real_escape_string($_GET['profile']); $sqlStr = "SELECT l.username, l.loginid, s.loginid, s.submissionid, s.title, s.url, s.datesubmitted, s.displayurl FROM submission AS s, login AS l WHERE l.username = '$profile', s.loginid = l.loginid ORDER BY s.datesubmitted DESC";

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• is a mysql temporary table unique for each user accessing the script that creates it...?

  - by SpikETidE

  Hi everyone... While looking for a way to temporarily save the search results when a user searches for a hotel free between particular dates i came across temporary tables. But certain questions are not answered even in mysql manual.... like... Will the temporary table be unique for each user that executes the script...? Or will it be overwritten when two different users run the script at the same time...? When will the table be destroyed..? When the user closes the browser window or just navigates away from the page in which the script runs...? Thanks for your clarifications...

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• can oracle types be updated like tables?

  - by Omnipresent

  I am converting GTT's to oracle types as explained in an excellent answer by APC. however, some GTT's are being updated based on a select query from another table. For example: UPDATE my_gtt_1 c SET (street, city, STATE, zip) = (SELECT src.unit_address, src.unit_city, src.unit_state, src.unit_zip_code FROM (SELECT mbr.ROWID row_id, unit_address, RTRIM(a.unit_city) unit_city, RTRIM(a.unit_state) unit_state, RTRIM(a.unit_zip_code) unit_zip_code FROM table_1 b, table_2 a, my_gtt_1 mbr WHERE type = 'ABC' AND id = b.ssn_head AND a.h_id = b.h_id AND row_id >= v_start_row AND row_id <= v_end_row) src WHERE c.ROWID = src.row_id) WHERE state IS NULL OR state = ' '; if my_gtt_1 was not a global temporary table but an oracle collection type then is it possible to do updates this complex? Or in these cases we are better off using the global temporary table?

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• MySQL Ratings From Two Tables

  - by DirtyBirdNJ

  I am using MySQL and PHP to build a data layer for a flash game. Retrieving lists of levels is pretty easy, but I've hit a roadblock in trying to fetch the level's average rating along with it's pointer information. Here is an example data set: levels Table: level_id | level_name 1 | Some Level 2 | Second Level 3 | Third Level ratings Table: rating_id | level_id | rating_value 1 | 1 | 3 2 | 1 | 4 3 | 1 | 1 4 | 2 | 3 5 | 2 | 4 6 | 2 | 1 7 | 3 | 3 8 | 3 | 4 9 | 3 | 1 I know this requires a join, but I cannot figure out how to get the average rating value based on the level_id when I request a list of levels. This is what I'm trying to do: SELECT levels.level_id, AVG(ratings.level_rating WHERE levels.level_id = ratings.level_id) FROM levels I know my SQL is flawed there, but I can't figure out how to get this concept across. The only thing I can get to work is returning a single average from the entire ratings table, which is not very useful. Ideal Output from the above conceptually valid but syntactically awry query would be: level_id | level_rating 1| 3.34 2| 1.00 3| 4.54 My main issue is I can't figure out how to use the level_id of each response row before the query has been returned. It's like I want to use a placeholder... or an alias... I really don't know and it's very frustrating. The solution I have in place now is an EPIC band-aid and will only cause me problems long term... please help!

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• How to map to tables in database PHPMyAdmin

  - by thegrede

  I'm working now on a project which a user can save their own coupon codes on the websites, so I want to know what is the best to do that, Lets say, I have 1 table with the users, like this, userId | firstName | lastName | codeId and then I have a table of the coupon codes, like this, codeId | codeNumber So what I can do is to connect the codeId to userId so when someone saves the coupons goes the codeId from the coupon table into the codeId of the users table, But now what if when a user have multiple coupons what do I do it should be connected to the user? I have 2 options what to do, Option 1, Saving the codeId from coupons table into the codeId of users table like 1,2,3,4,5, Option 2 To make a new row into the coupons table and to connect the user to the code with adding another field in the coupon table userId and putting into it the user which has added the coupon his userId of the users table, So what of the two options is better to do? Thanks you guys.

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• Can't Insert Data Into Tables Containing Auto Increment Primary Key Using PHP Prepared Statements

  - by Drew

  I know I have that my connection to the database works, and a test I did using no auto-increment id worked fine for me. The code below refuses to work and I can't find a a way around it. My table has 3 columns, ID (auto increment), name and value. What do I need to change in order to get this to work? Thanks in advance //create placeholder query $query = "INSERT INTO prepared_test (name, value) VALUES (?,?)"; //prepare the query $stmt = mysqli_prepare($connection, $query); $name = 'steve'; $value = 45; mysqli_bind_param($stmt, array(MYSQLI_BIND_STRING, MYSQLI_BIND_INT), $name, $value); mysqli_execute($stmt); if(mysqli_stmt_affected_rows($stmt) != 1) die("issues"); mysqli_stmt_close($stmt); $connection-close();

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• iPhone: Grouped tables and navigation controller issues

  - by Jack Griffiths

  Hi there, I've set up a grouped table on my app, and pushing to new views works fine. Except for one thing. The titles and stack layout are all weird. Here's the breakdown: I have two sections in my table. When I tap on the first row in the first section, it takes me to the correct view, but the title of the new view is the name of the first row in the second section of the table. In turn, the second row in the first section's title is the second row in the second section's title. If I tap on the second row in the second section of the root view table, the navigation button goes to the second row in the first section of the table. So here's a diagram of my table: Table Section 1 Row 1 Row 2 Row 3 Table Section 2 Row A Row B Row C So if I tap on row 3, the title of the pushed view is Row C. The navigation button tells me to go back to Row 3, then eventually ending up at the root view. Here's my implementation file pushing the views: - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath { //CSS if ([[arryClientSide objectAtIndex:indexPath.row] isEqual:@"CSS"]) { CSSViewController *css = [[CSSViewController alloc] initWithNibName:@"CSSViewController" bundle:nil]; [css setTitle:@"CSS"]; [self.navigationController pushViewController:css animated:YES]; } //HTML if ([[arryClientSide objectAtIndex:indexPath.row] isEqual:@"HTML"]) { HTMLViewController *html = [[HTMLViewController alloc] initWithNibName:@"HTMLViewController" bundle:nil]; [html setTitle:@"HTML"]; [self.navigationController pushViewController:html animated:YES]; } //JS if ([[arryClientSide objectAtIndex:indexPath.row] isEqual:@"JavaScript"]) { JSViewController *js = [[JSViewController alloc] initWithNibName:@"JSViewController" bundle:nil]; [js setTitle:@"JavaScript"]; [self.navigationController pushViewController:js animated:YES]; } //PHP if ([[arryServerSide objectAtIndex:indexPath.row] isEqual:@"PHP"]) { PHPViewController *php = [[PHPViewController alloc] initWithNibName:@"PHPViewController" bundle:nil]; [php setTitle:@"PHP"]; [self.navigationController pushViewController:php animated:YES]; } //SQL if ([[arryServerSide objectAtIndex:indexPath.row] isEqual:@"SQL"]) { SQLViewController *sql = [[SQLViewController alloc] initWithNibName:@"SQLViewController" bundle:nil]; [sql setTitle:@"SQL"]; [self.navigationController pushViewController:sql animated:YES]; } & the array feeding the table's data: - (void)viewDidLoad { [super viewDidLoad]; arryClientSide = [[NSArray alloc] initWithObjects:@"CSS",@"HTML",@"JavaScript",nil]; arryServerSide = [[NSArray alloc] initWithObjects:@"Objective-C", @"PHP",@"SQL",nil]; // arryResources = [[NSArray alloc] initWithObjects:@"HTML Colour Codes", @"Useful Resources", @"About",nil]; self.title = @"Select a Language"; [super viewDidLoad]; // Uncomment the following line to display an Edit button in the navigation bar for this view controller. // self.navigationItem.rightBarButtonItem = self.editButtonItem; } Any help would be greatly appreciated. Jack

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