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• Attributes passed to .build() dont show up in the query

  - by Sebastian

  Hi there guys! Hope your all enjoying your hollydays. Ive run into a pretty funny problem when trying to insert rows into a really really simple database table. The basic idea is pretty simple. The user selects one/multiple users in a multiselect which are supposed to be added to a group. This piece of code will insert a row into the user_group_relationships table, but the users id always @group = Group.find(params[:group_id]) params[:newMember][:users].each do |uid| # For debugging purposes. puts 'Uid:'+uid @rel = @group.user_group_relationships.build( :user_id => uid.to_i ) @rel.save end The user id always gets inserted as null even though it is clearly there. You can see the uid in this example is 5, so it should work. Uid:5 ... SQL (0.3ms) INSERT INTO "user_group_relationships" ("created_at", "group_id", "updated_at", "user_id") VALUES ('2010-12-27 14:03:24.331303', 2, '2010-12-27 14:03:24.331303', NULL) Any ideas why this fails?

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• Constructors for C++ objects

  - by sasquatch

  I have class Person as following : class Person { char* name; int age; }; Now I need to add two contructors. One taking no arguments, that inserts field values to dynamically allocated resources. Second taking (char*, int) arguments initialized by initialization list. Last part is to define a destructor showing information about destroying objects and deallocating dynamically allocated resources. How to perform this task ? That's what I already have : class Person { char* name; int age; public: Person(){ this->name = new *char; this->age = new int; } Person(char* c, int i){ } };

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• Oracle - pl sql selecting from SYS_REFCURSOR

  - by Einstein

  I have a function that returns a SYS_REFCURSOR that has a single row but multiple columns. What I'm looking to do is to be able to have a SQL query that has nested sub-queries using the column values returned in the SYS_REFCURSOR. Alternative ideas such as types, etc would be appreciated. Code below is me writing on-the-fly and hasn't been validated for syntax. --Oracle function CREATE DummyFunction(dummyValue AS NUMBER) RETURN SYS_REFCURSOR IS RETURN_DATA SYS_REFCURSOR; BEGIN OPEN RETURN_DATA SELECT TO_CHAR(dummyValue) || 'A' AS ColumnA ,TO_CHAR(dummyValue) || 'B' AS ColumnB FROM DUAL; RETURN RETURN_DATA; END; --sample query with sub-queries; does not work SELECT SELECT ColumnA FROM DummyFunction(1) FROM DUAL AS ColumnA ,SELECT ColumnB FROM DummyFunction(1) FROM DUAL AS ColumnB FROM DUAL;

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• how to select and group mysql data based on the follwoing table

  - by user1151680

  how can I achieve the desired result in mysql if my table looks like this. result|year 1 |2011 2 |2011 1 |2011 0 |2011 1 |2012 2 |2012 1 = Won, 2 = lost, 0 = draw Every year can have multiple values like this. Not sure how I can get the desired result like below. year won lost draw totalPlayed 2011 2 1 1 3 2012 1 1 0 2 I have tried the following query but does not get the desired result select year, league_types.league_name, sum(if(result = 1,1,0)) as won, sum(if(result = 0,1,0)) as draw, sum(if(result = 4,1,0)) as noResult, sum(if(result = 2,1,0)) as lost, sum(if(result = 3,1,0)) as tied, sum(if(result > 0 and result < 4,1,0)) as played from match_score_card inner join fixtures on match_score_card.match_id = fixtures.match_id inner join league_types on fixtures.league_id = league_types.league_id where team_id = 1 group by year order by year desc

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• How should I implement simple caches with concurrency on Redis?

  - by solublefish

  Background I have a 2-tier web service - just my app server and an RDBMS. I want to move to a pool of identical app servers behind a load balancer. I currently cache a bunch of objects in-process. I hope to move them to a shared Redis. I have a dozen or so caches of simple, small-sized business objects. For example, I have a set of Foos. Each Foo has a unique FooId and an OwnerId. One "owner" may own multiple Foos. In a traditional RDBMS this is just a table with an index on the PK FooId and one on OwnerId. I'm caching this in one process simply: Dictionary<int,Foo> _cacheFooById; Dictionary<int,HashSet<int>> _indexFooIdsByOwnerId; Reads come straight from here, and writes go here and to the RDBMS. I usually have this invariant: "For a given group [say by OwnerId], the whole group is in cache or none of it is." So when I cache miss on a Foo, I pull that Foo and all the owner's other Foos from the RDBMS. Updates make sure to keep the index up to date and respect the invariant. When an owner calls GetMyFoos I never have to worry that some are cached and some aren't. What I did already The first/simplest answer seems to be to use plain ol' SET and GET with a composite key and json value: SET( "ServiceCache:Foo:" + theFoo.Id, JsonSerialize(theFoo)); I later decided I liked: HSET( "ServiceCache:Foo", theFoo.FooId, JsonSerialize(theFoo)); That lets me get all the values in one cache as HVALS. It also felt right - I'm literally moving hashtables to Redis, so perhaps my top-level items should be hashes. This works to first order. If my high-level code is like: UpdateCache(myFoo); AddToIndex(myFoo); That translates into: HSET ("ServiceCache:Foo", theFoo.FooId, JsonSerialize(theFoo)); var myFoos = JsonDeserialize( HGET ("ServiceCache:FooIndex", theFoo.OwnerId) ); myFoos.Add(theFoo.OwnerId); HSET ("ServiceCache:FooIndex", theFoo.OwnerId, JsonSerialize(myFoos)); However, this is broken in two ways. Two concurrent operations can read/modify/write at the same time. The latter "wins" the final HSET and the former's index update is lost. Another operation could read the index in between the first and second lines. It would miss a Foo that it should find. So how do I index properly? I think I could use a Redis set instead of a json-encoded value for the index. That would solve part of the problem since the "add-to-index-if-not-already-present" would be atomic. I also read about using MULTI as a "transaction" but it doesn't seem like it does what I want. Am I right that I can't really MULTI; HGET; {update}; HSET; EXEC since it doesn't even do the HGET before I issue the EXEC? I also read about using WATCH and MULTI for optimistic concurrency, then retrying on failure. But WATCH only works on top-level keys. So it's back to SET/GET instead of HSET/HGET. And now I need a new index-like-thing to support getting all the values in a given cache. If I understand it right, I can combine all these things to do the job. Something like: while(!succeeded) { WATCH( "ServiceCache:Foo:" + theFoo.FooId ); WATCH( "ServiceCache:FooIndexByOwner:" + theFoo.OwnerId ); WATCH( "ServiceCache:FooIndexAll" ); MULTI(); SET ("ServiceCache:Foo:" + theFoo.FooId, JsonSerialize(theFoo)); SADD ("ServiceCache:FooIndexByOwner:" + theFoo.OwnerId, theFoo.FooId); SADD ("ServiceCache:FooIndexAll", theFoo.FooId); EXEC(); //TODO somehow set succeeded properly } Finally I'd have to translate this pseudocode into real code depending how my client library uses WATCH/MULTI/EXEC; it looks like they need some sort of context to hook them together. All in all this seems like a lot of complexity for what has to be a very common case; I can't help but think there's a better, smarter, Redis-ish way to do things that I'm just not seeing. How do I lock properly? Even if I had no indexes, there's still a (probably rare) race condition. A: HGET - cache miss B: HGET - cache miss A: SELECT B: SELECT A: HSET C: HGET - cache hit C: UPDATE C: HSET B: HSET ** this is stale data that's clobbering C's update. Note that C could just be a really-fast A. Again I think WATCH, MULTI, retry would work, but... ick. I know in some places people use special Redis keys as locks for other objects. Is that a reasonable approach here? Should those be top-level keys like ServiceCache:FooLocks:{Id} or ServiceCache:Locks:Foo:{Id}? Or make a separate hash for them - ServiceCache:Locks with subkeys Foo:{Id}, or ServiceCache:Locks:Foo with subkeys {Id} ? How would I work around abandoned locks, say if a transaction (or a whole server) crashes while "holding" the lock?

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• How to get a dynamic attribute name in cfloop over query in ColdFusion

  - by Kip

  I'm inside a cfloop over a query. I want to get an attribute, but I won't know what that attribute will be until runtime. Using #qryResult[MyAttr]# fails with the error "Complex object types cannot be converted to simple values." What is the syntax for doing this? Here is a simplified example: <cfquery datasource="TestSource" name="qryResult"> SELECT * FROM MyTable </cfquery> <cfloop query="qryResult"> <cfset MyAttr="autoid" /> <cfoutput> Test 1: #qryResult.autoid# <br/> <!--- succeeds ---> Test 2: #qryResult[MyAttr]# <br/> <!--- fails ---> </cfoutput> </cfloop>

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• SQL validation!

  - by Filip

  I am pretty new in SQL so this may be a stupid question... I have a form in PHP which fills in few fields in my SQL table. I have this code: $sql="INSERT INTO $tbl_name (app_name, app_path, short_desc, full_desc) VALUES ('$_POST[app_name]', '$_POST[app_path]', '$_POST[short_desc]', '$_POST[full_desc]')"; But even app_name and app_path are NOT NULL columns, the query can be executed if there is no text in these fields in the form. So, my question is: How to stop the execution of the query if there is no text in the NOT NULL fields ?

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• usage of intval & real_escape_string when sanitizing integers

  - by paulus

  dear All. I'm using integer PKs in some tables of mysql database. Before input from PHP script, I am doing some sanitizing, which includes intval($id) and $mysqli-real_escape_string(). The queries are quite simple insert into `tblproducts`(`supplier_id`,`description`) values('$supplier_id','$description') In this example, $description goes through real_escape_string(), while $supplier_id only being intval()'ed. I'm just curious, if there're any situations, when I need to apply both intval and real_escape_string to integer I'm inserting into DB? So basically do I really need to use? $supplier_id = intval($mysqli->real_escape_string($supplier_id)); Thank you.

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• C# GroupJoin effectiveness

  - by bsnote

  without using GroupJoin: var playersDictionary = players.ToDictionary(player => player.Id, element => new PlayerDto { Rounds = new List<RoundDto>() }); foreach (var round in rounds) { PlayerDto playerDto; playersDictionary.TryGetValue(round.PlayerId, out playerDto); if (playerDto != null) { playerDto.Rounds.Add(new RoundDto { }); } } var playerDtoItems = playersDictionary.Values; using GroupJoin: var playerDtoItems = from player in players join round in rounds on player.Id equals round.PlayerId into playerRounds select new PlayerDto { Rounds = playerRounds.Select(playerRound => new RoundDto {}) }; Which of these two pieces is more efficient?

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• Loading HTML into a Cocoa app with WebView and change text

  - by Domness

  Right, so far I've got this for loading up a HTML file from within my app: NSString *path1 = [[NSBundle mainBundle] pathForResource:@"file" ofType:@"html"]; NSString *html = [NSString stringWithContentsOfFile:path1 encoding:NSUTF8StringEncoding error:nil]; [[webView mainFrame] loadHTMLString:html baseURL:[NSURL fileURLWithPath:[[NSBundle mainBundle]bundlePath]]]; Which works loading the file up into the app's WebView. But I want to change some values in the HTML (or PHP if it works by using $_REQUEST/$_GET), for example, I have a table with some text in it and I want to change this text from an NSString etc. How would I go about this?

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• Syncronizing indices of function pointer table to table contents

  - by Thomas Matthews

  In the embedded system I'm working on, we are using a table of function pointers to support proprietary Dynamic Libraries. We have a header file that uses named constants (#define) for the function pointer indices. These values are used in calculating the location in the table of the function's address. Example: *(export_table.c)* // Assume each function in the table has an associated declaration typedef void (*Function_Ptr)(void); Function_Ptr Export_Function_Table[] = { 0, Print, Read, Write, Process, }; Here is the header file: *export_table.h* #define ID_PRINT_FUNCTION 1 #define ID_READ_FUNCTION 2 #define ID_WRITE_FUNCTION 3 #define ID_PROCESS_FUNCTION 4 I'm looking for a scheme to define the named constants in terms of their location in the array so that when the order of the functions changes, the constants will also change. (Also, I would like the compiler or preprocessor to calculate the indices to avoid human mistakes like typeo's.)

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• password/login system in php

  - by Jonathan

  For a login system in php would this be a suitable outline of how it would work: users types in username and password, clicks login button. Checks if user exists in database, if it does, then retrieve the salt for that user hash the password and salt (would this be done on the client or server side? I think client side would be better, but php is server side so how would you do this?) check value against value in database, if the values match then user has typed in correct password and they are logged in.

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• Refreshing <div> and load data from php

  - by forgatn

  I have on my page and there is a tag where is some and values filled from mySQL DB. I need some JavaScript I think. When I select one option, I want to display in this propriate DATAs which are in DB. without refreshing whole page. Can you tell me how to do it, if you know that please?:) <div id="country1" class="tabcontent"> <label>Choose protocol</label> <SELECT name="cisloprot"> <?php $con = mysql_connect("localhost", "root", "123456"); $sql = "SELECT kod FROM prot GROUP BY kod"; $rs = mysql_query($sql,$con); while ($r = mysql_fetch_array($rs)) { echo "<OPTION VALUE=".$r['kod'].">".$r['kod']."</OPTION>"; } ?> </SELECT> </div>

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• overwriting arguments in t-sql functions

  - by chuck taylor

  I was playing around with some code and realized that it is possible to overwrite the argument to a t-sql function. i.e., create function someFn(@date date) as begin if @date is null set @date = getdate() will set @date to be today's date if the argument was null. This appears only to make any sense if t-sql is treating their arguments as references not values. I realized that I don't actually know what the t-sql rules are for cases like this and was hoping someone could elaborate what is going on here. (I don't ever recall seeing any value vs. reference discussion with respect to t-sql code for that matter actually..)

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• INSERT 0..n records into table 'A' based on content of table 'B' in MySql 5

  - by Robert Gowland

  Using MySql 5, I have a task where I need to update one table based on the contents of another table. For example, I need to add 'A1' to table 'A' if table 'B' contains 'B1'. I need to add 'A2a' and 'A2b' to table 'A' if table 'B' contains 'B2', etc.. In our case, the value in table 'B' we're interested is an enum. Right now I have a stored procedure containing a series of statements like: INSERT INTO A SELECT 'A1' FROM B WHERE B.Value = 'B1'; --Repeat for 'B2' -> 'A2a'; 'B2' -> 'A2b'; 'B3' -> 'A3', etc... Is there a nicer more DRY way of accomplishing this? Edit: There may be values in table 'B' that have no equivalent value for table 'A'.

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• Checking if a string's characters are ascending alphabetically and its ascent is evenly spaced python

  - by FRU5TR8EDD

  So need to check if a string's characters are ascending alphabetically and if that ascent is evenly spaced. a = "abc" b = "ceg" So a is alphabetically ascending and it's spacing is 1 (if you convert to the ordinal values they are 97,98,99). And b is also alphabetically ascending and it's spacing is 2 (99,101,103). And I am sticking with the following code: a = 'jubjub' words1 = [] ords = [ord(letter) for letter in a] diff = ords[1] - ords[0] for ord_val in range(1, len(ords)-1): if diff > 0: if ords[ord_val + 1] - ords[ord_val] == diff: if a not in words1: words1.append((a, diff)) print words1 How come 'jubjub' works, 'ace' works, but 'catcat' doesn't?

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• How SqlDataAdapter works internally?

  - by tigrou

  I wonder how SqlDataAdapter works internally, especially when using UpdateCommand for updating a huge DataTable (since it's usually a lot faster that just sending sql statements from a loop). Here is some idea I have in mind : It creates a prepared sql statement (using SqlCommand.Prepare()) with CommandText filled and sql parameters initialized with correct sql types. Then, it loops on datarows that need to be updated, and for each record, it updates parameters values, and call SqlCommand.ExecuteNonQuery(). It creates a bunch of SqlCommand objects with everything filled inside (CommandText and sql parameters). Several SqlCommands at once are then batched to the server (depending of UpdateBatchSize). It uses some special, low level or undocumented sql driver instructions that allow to perform an update on several rows in a effecient way (rows to update would need to be provided using a special data format and a the same sql query (UpdateCommand here) would be executed against each of these rows).

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• problme with javascript map/object

  - by akshay

  I am using javascript map to store keys and values.Later on I check if specified key is present in map or not, but it sometimes gives correct result but sometimes it dont.I tried to print the map using console.log(mapname), it shows all keys, but i i try to check if some specified key is presnt sometimes it gives wrong answer. Am using following code: //following code is called n times in loop with different/same vales of x myMap : new Object(); var key = x ; //populated dynamically actually myMap[key] ="dummyval"; if(myIdMap[document.getElementById("abc").value.trim()]!=null) alert('present' ); else alert('not present'); What can be the possible problem?

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• how to get value in text field

  - by air

  i have one text field and setting its name & values from php like <input type="text" id="qtyProductID_' . $productID . '" size="3" value="' . $totalItems . '" > i also have image button for click event <a href=fun.php?action=update&productID=' . $productID . ' onClick="return false;"><img src="images/update.jpg" id="updateProductID_' . $productID . '"></a> now after click in JS file i want to get value of text field i click var productIDValSplitter = (this.id).split("_"); var productIDVal = productIDValSplitter[1]; var tqty = $('#qtyProductID_'.productIDVal[1]).attr('value'); alert(tqty); i am getting error i am looking for how to set the variable name in $('#qtyProductID_'.productIDVal[1]) Thanks

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• how to request collection of fields in mvc

  - by frosty

  i have the following foreach. Inside you'll see a text box for quantity. At the bottom of the page there is submit button. What is the best practise for saving a collection of fields like this in asp.net MVC. ie how would i get the values in my controller <% foreach(var item in Model.Results) { %> <tr class="RowStyle"> <td><input name="quantity" value="<%= item.Quantity %>" class"input-30" /></td> </tr> <% } %>

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• If I take a large datatype. Will it affect performance in sql server

  - by Shantanu Gupta

  If i takes larger datatype where i know i should have taken datatype that was sufficient for possible values that i will insert into a table will affect any performance in sql server in terms of speed or any other way. eg. IsActive (0,1,2,3) not more than 3 in any case. I know i must take tinyint but due to some reasons consider it as compulsion, i am taking every numeric field as bigint and every character field as nVarchar(Max) Please give statistics if possible, to let me try to overcoming that compulsion. I need some solid analysis that can really make someone rethink before taking any datatype.

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• Asp.Net gridview customization

  - by Kunal

  Hi If you go to http://ifdefined.com/btnet/bugs.aspx you will see a long list of sample data in an asp.net gridview control. What I need to do is something similar. I need to implement the filtering system by placing dropdown controls with dynamic values on the headers and then filter the record according to them. If you look carefully they are filtering the data based on multiple drodown selections as well. Kindly help me out. Any kind of input is highly appreciated. Thanks in advance for your time.

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• What is this Hash-like/Tree-like Construct Called?

  - by viatropos

  I want to create a "Config" class that acts somewhere between a hash and a tree. It's just for storing global values, which can have a context. Here's how I use it: Config.get("root.parent.child_b") #=> "value" Here's what the class might look like: class Construct def get(path) # split path by "." # search tree for nodes end def set(key, value) # split path by "." # create tree node if necessary # set tree value end def tree { :root => { :parent => { :child_a => "value", :child_b => "another value" }, :another_parent => { :something => { :nesting => "goes on and on" } } } } end end Is there a name for this kind of thing, somewhere between Hash and Tree (not a Computer Science major)? Basically a hash-like interface to a tree.

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• How to update existing record if the one being saved has the same key?

  - by Pavel Shved

  MySQL has a very nice option for INSERT statement, which is particularly helpful for join tables without the id column. It inserts a record, but, instead of throwing an error if its key clashed with the existing one, that record is updated. Here's an example: INSERT INTO table (key1,key2,data) VALUES (1,2,3) ON DUPLICATE KEY UPDATE c=3; How to achieve the same with ActiveRecord? The code looks like this: class Model < ActiveRecord::Base belongs_to :key1 belongs_to :key2 end record = Model.new record.key1 = key1 record.key2 = key2 record.data = 'new data' record.WHAT? #Inserts or updates `data` for the existing record

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• I am having trouble with my first project in ruby on rails

  - by Sebastian

  Here's my index action in the books controller: http://pastebin.com/XdtGRQKV Here's the view for the action i just mentioned: http://pastebin.com/nQFy400m Here's the result without being logged in: http://i.imgur.com/rQoiw.jpg Here's the result when i'm logged in with the user 'admin': http://i.imgur.com/E1CUr.jpg So the problem is that, in the view, before line 25 the 'user' variable seems to be empty ( or not loaded), and after line 25 the variable 'user' has the expected values. I have tried initializing a variable in the index method of the books controller but get exactly the same results. Thanks in advance! BTW had to make the links text because of stackoverflow limit.

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