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• Selecting unique records in XSLT/XPath

  - by Daniel I-S

  I have to select only unique records from an XML document, in the context of an <xsl:for-each> loop. I am limited by Visual Studio to using XSL 1.0. <availList> <item> <schDate>2010-06-24</schDate> <schFrmTime>10:00:00</schFrmTime> <schToTime>13:00:00</schToTime> <variousOtherElements></variousOtherElements> </item> <item> <schDate>2010-06-24</schDate> <schFrmTime>10:00:00</schFrmTime> <schToTime>13:00:00</schToTime> <variousOtherElements></variousOtherElements> </item> <item> <schDate>2010-06-25</schDate> <schFrmTime>10:00:00</schFrmTime> <schToTime>12:00:00</schToTime> <variousOtherElements></variousOtherElements> </item> <item> <schDate>2010-06-26</schDate> <schFrmTime>13:00:00</schFrmTime> <schToTime>14:00:00</schToTime> <variousOtherElements></variousOtherElements> </item> <item> <schDate>2010-06-26</schDate> <schFrmTime>10:00:00</schFrmTime> <schToTime>12:00:00</schToTime> <variousOtherElements></variousOtherElements> </item> </availList> The uniqueness must be based on the value of the three child elements: schDate, schFrmTime and schToTime. If two item elements have the same values for all three child elements, they are duplicates. In the above XML, items one and two are duplicates. The rest are unique. As indicated above, each item contains other elements that we do not wish to include in the comparison. 'Uniqueness' should be a factor of those three elements, and those alone. I have attempted to accomplish this through the following: availList/item[not(schDate = preceding:: schDate and schFrmTime = preceding:: schFrmTime and schToTime = preceding:: schToTime)] The idea behind this is to select records where there is no preceding element with the same schDate, schFrmTime and schToTime. However, its output is missing the last item. This is because my XPath is actually excluding items where all of the child element values are matched within the entire preceding document. No single item matches all of the last item's child elements - but because each element's value is individually present in another item, the last item gets excluded. I could get the correct result by comparing all child values as a concatenated string to the same concatenated values for each preceding item. Does anybody know of a way I could do this?

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• Unique Alpha numeric generator

  - by AAA

  Hi, I want to give our users in the database a unique alpha-numeric id. I am using the code below, will this always generate a unique id? Below is the updated version of the code: old php: // Generate Guid function NewGuid() { $s = strtoupper(md5(uniqid(rand(),true))); $guidText = substr($s,0,8) . '-' . substr($s,8,4) . '-' . substr($s,12,4). '-' . substr($s,16,4). '-' . substr($s,20); return $guidText; } // End Generate Guid $Guid = NewGuid(); echo $Guid; echo "<br><br><br>"; New PHP: // Generate Guid function NewGuid() { $s = strtoupper(uniqid("something",true)); $guidText = substr($s,0,8) . '-' . substr($s,8,4) . '-' . substr($s,12,4). '-' . substr($s,16,4). '-' . substr($s,20); return $guidText; } // End Generate Guid $Guid = NewGuid(); echo $Guid; echo "<br><br><br>"; Will the second (new php) code guarantee 100% uniqueness. Final code: PHP // Generate Guid function NewGuid() { $s = strtoupper(uniqid(rand(),true)); $guidText = substr($s,0,8) . '-' . substr($s,8,4) . '-' . substr($s,12,4). '-' . substr($s,16,4). '-' . substr($s,20); return $guidText; } // End Generate Guid $Guid = NewGuid(); echo $Guid; $alphabet = '123456789abcdefghijkmnopqrstuvwxyzABCDEFGHJKLMNPQRSTUVWXYZ'; function base_encode($num, $alphabet) { $base_count = strlen($alphabet); $encoded = ''; while ($num >= $base_count) { $div = $num/$base_count; $mod = ($num-($base_count*intval($div))); $encoded = $alphabet[$mod] . $encoded; $num = intval($div); } if ($num) $encoded = $alphabet[$num] . $encoded; return $encoded; } function base_decode($num, $alphabet) { $decoded = 0; $multi = 1; while (strlen($num) > 0) { $digit = $num[strlen($num)-1]; $decoded += $multi * strpos($alphabet, $digit); $multi = $multi * strlen($alphabet); $num = substr($num, 0, -1); } return $decoded; } echo base_encode($Guid, $alphabet); } So for more stronger uniqueness, i am using the $Guid as the key generator. That should be ok right?

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• Breaking 1NF to model subset constraints. Does this sound sane?

  - by Chris Travers

  My first question here. Appologize if it is in the wrong forum but this seems pretty conceptual. I am looking at doing something that goes against conventional wisdom and want to get some feedback as to whether this is totally insane or will result in problems, so critique away! I am on PostgreSQL 9.1 but may be moving to 9.2 for this part of this project. To re-iterate: Does it seem sane to break 1NF in this way? I am not looking for debugging code so much as where people see problems that this might lead. The Problem In double entry accounting, financial transactions are journal entries with an arbitrary number of lines. Each line has either a left value (debit) or a right value (credit) which can be modelled as a single value with negatives as debits and positives as credits or vice versa. The sum of all debits and credits must equal zero (so if we go with a single amount field, sum(amount) must equal zero for each financial journal entry). SQL-based databases, pretty much required for this sort of work, have no way to express this sort of constraint natively and so any approach to enforcing it in the database seems rather complex. The Write Model The journal entries are append only. There is a possibility we will add a delete model but it will be subject to a different set of restrictions and so is not applicable here. If and when we allow deletes, we will probably do them using a simple ON DELETE CASCADE designation on the foreign key, and require that deletes go through a dedicated stored procedure which can enforce the other constraints. So inserts and selects have to be accommodated but updates and deletes do not for this task. My Proposed Solution My proposed solution is to break first normal form and model constraints on arrays of tuples, with a trigger that breaks the rows out into another table. CREATE TABLE journal_line ( entry_id bigserial primary key, account_id int not null references account(id), journal_entry_id bigint not null, -- adding references later amount numeric not null ); I would then add "table methods" to extract debits and credits for reporting purposes: CREATE OR REPLACE FUNCTION debits(journal_line) RETURNS numeric LANGUAGE sql IMMUTABLE AS $$ SELECT CASE WHEN $1.amount < 0 THEN $1.amount * -1 ELSE NULL END; $$; CREATE OR REPLACE FUNCTION credits(journal_line) RETURNS numeric LANGUAGE sql IMMUTABLE AS $$ SELECT CASE WHEN $1.amount > 0 THEN $1.amount ELSE NULL END; $$; Then the journal entry table (simplified for this example): CREATE TABLE journal_entry ( entry_id bigserial primary key, -- no natural keys :-( journal_id int not null references journal(id), date_posted date not null, reference text not null, description text not null, journal_lines journal_line[] not null ); Then a table method and and check constraints: CREATE OR REPLACE FUNCTION running_total(journal_entry) returns numeric language sql immutable as $$ SELECT sum(amount) FROM unnest($1.journal_lines); $$; ALTER TABLE journal_entry ADD CONSTRAINT CHECK (((journal_entry.running_total) = 0)); ALTER TABLE journal_line ADD FOREIGN KEY journal_entry_id REFERENCES journal_entry(entry_id); And finally we'd have a breakout trigger: CREATE OR REPLACE FUNCTION je_breakout() RETURNS TRIGGER LANGUAGE PLPGSQL AS $$ BEGIN IF TG_OP = 'INSERT' THEN INSERT INTO journal_line (journal_entry_id, account_id, amount) SELECT NEW.id, account_id, amount FROM unnest(NEW.journal_lines); RETURN NEW; ELSE RAISE EXCEPTION 'Operation Not Allowed'; END IF; END; $$; And finally CREATE TRIGGER AFTER INSERT OR UPDATE OR DELETE ON journal_entry FOR EACH ROW EXECUTE_PROCEDURE je_breaout(); Of course the example above is simplified. There will be a status table that will track approval status allowing for separation of duties, etc. However the goal here is to prevent unbalanced transactions. Any feedback? Does this sound entirely insane? Standard Solutions? In getting to this point I have to say I have looked at four different current ERP solutions to this problems: Represent every line item as a debit and a credit against different accounts. Use of foreign keys against the line item table to enforce an eventual running total of 0 Use of constraint triggers in PostgreSQL Forcing all validation here solely through the app logic. My concerns are that #1 is pretty limiting and very hard to audit internally. It's not programmer transparent and so it strikes me as being difficult to work with in the future. The second strikes me as being very complex and required a series of contraints and foreign keys against self to make work, and therefore it strikes me as complex, hard to sort out at least in my mind, and thus hard to work with. The fourth could be done as we force all access through stored procedures anyway and this is the most common solution (have the app total things up and throw an error otherwise). However, I think proof that a constraint is followed is superior to test cases, and so the question becomes whether this in fact generates insert anomilies rather than solving them. If this is a solved problem it isn't the case that everyone agrees on the solution....

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• MySQL id sequence

  - by Michal Fronczyk

  Is this a correct way for id generation in MySQL ? INSERT INTO Picture (PictureId,First_pick,Title,Description,File_Name,Is_Vertical)VALUES ((SELECT max(pictureid)+1 FROM Picture),0,?,?,?,?) I mean if it is guaranted that PictureId will be unique when this query is run by many threads ? I can't modify table structure. Should I use any specific locks, index or transaction isolation level ? Regards, Michal

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• Conditional SQLite check constraint?

  - by Rezzie

  I have a table defined by the following SQL: CREATE TABLE test ( id integer PRIMARY KEY NOT NULL UNIQUE, status text NOT NULL, enddate date, /* Checks */ CHECK (status IN ("Current", "Complete")) ); I'd like to add a constraint that requires enddate to be non-null if the status is "Complete". Is this possible? I am using SQLite v3.6.16.

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• Saving auto increment in MySQL

  - by oshafran

  Hello, I am trying to sync between 2 tables: I have active table where has auto_increment, and I have archive table with the same values. I would like both ID's to be unique (between the tables as well) - I mean, I would like to save auto incremenet, and if I UNION both table I still have uniqness. How can I do that? Is there a possibility to save auto increment when mysql is off?

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• Grails' GORM constraint question

  - by xain

  Hi, I have the following Domain Class: class Metric { String name float value static belongsTo = [Person,Corporation] static indexes = { name() } } How can I add a constraint so Person,Corporation and name are unique ? Thanks.

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• Generate unique hashes for django models

  - by becomingGuru

  I want to use unique hashes for each model rather than ids. I implemented the following function to use it across the board easily. import random,hashlib from base64 import urlsafe_b64encode def set_unique_random_value(model_object,field_name='hash_uuid',length=5,use_sha=True,urlencode=False): while 1: uuid_number = str(random.random())[2:] uuid = hashlib.sha256(uuid_number).hexdigest() if use_sha else uuid_number uuid = uuid[:length] if urlencode: uuid = urlsafe_b64encode(uuid)[:-1] hash_id_dict = {field_name:uuid} try: model_object.__class__.objects.get(**hash_id_dict) except model_object.__class__.DoesNotExist: setattr(model_object,field_name,uuid) return I'm seeking feedback, how else could I do it? How can I improve it? What is good bad and ugly about it?

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• jQuery animate() - multiple selectors and variables, a unique animate() call

  - by ozke

  Hi guys, I am resizing several divs in a loop with animate() in jQuery. At the same time I am moving (left property, no resizing at all) the div where they are contained. Problem is, despite they have same duration the resize animate calls finish before the move call. They are out of sync. Is there any way of creating a list of selectors and its properties and then run a unique animate() call? Or, is there any alternative to make multiple animations happen at the same time? I've seen there's a property called step that happens every time animate loop happens but, again, each animate() call has it's own step call. Thanks in advance :)

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• Ensuring unique ID attribute for elements within ScriptControl

  - by Andy West

  I'm creating a control based on ScriptControl, and I'm overriding the Render method like this: protected override void Render(HtmlTextWriter writer) { RenderBeginTag(writer); writer.RenderBeginTag(HtmlTextWriterTag.Div); writer.Write("This is a test."); writer.RenderEndTag(); RenderEndTag(writer); } My question is, what if I want to assign the div an ID attribute and have it be unique on the page, even if there are mulitple instances of my control? I've seen other people's code that does this: writer.AddAttribute(HtmlTextWriterAttribute.Id, this.ID + "_divTest"); That will prevent naming conflicts between instances of my control, but what if I've already created a div elsewhere on the page that coincidentally has the same ID? I've also heard about implementing INamingContainer. Would that apply here? How could I use it?

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• Unique Key in MySql

  - by Vinodtiru

  I have a table with four Columns. Col1, Col2, Col3, and Col4. Col1, Col2, Col3 is string and Col4 is a integer primary key with Auto Increment. Now my requirement is to have unique combination of Col2 and Col3. I mean to say like. Insert into table(Col1,Col2,Col3) Values('val1','val2','val3'); Insert into table(Col1,Col2,Col3) Values('val4','val2','val3'); the second statement has to throw error as the same combination of 'val2','val3' is present in the table. But i cant make it as a primary key as i need a auto increment column and for that matter the col4 has to be primary. Please let me know a approach by which i can have both in my table. Any kind of help is appreciated. Thanks.

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• Nant xmlpoke and unique nodes

  - by Lou Franco

  I am trying to use an xmlpoke task to update a VS Project File (which is XML). In the Project root, there are multiple PropertyGroup nodes, I am trying to select the first one. The XML looks like this <Project> <PropertyGroup> </PropertyGroup> <PropertyGroup> </PropertyGroup> <PropertyGroup> </PropertyGroup> </Project> I am using an xpath of //Project/PropertyGroup[1] to get the first PropertyGroup, but I get the error: “Non-unique xpath given //Project/PropertyGroup[1]”.

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• Combining lists but getting unique members

  - by MC

  I have a bit of a special requirement when combining lists. I will try to illustrate with an example. Lets say I'm working with 2 lists of GamePlayer objects. GamePlayer has a property called LastGamePlayed. A unique GamePlayer is identified through the GamePlayer.ID property. Now I'd like to combine listA and listB into one list, and if a given player is present in both lists I'd like to keep the value from listA. I can't just combine the lists and use a comparer because my uniqueness is based on ID, and if my comparer checks ID I will not have control over whether it picks the element of listA or listB. I need something like: for each player in listB { if not listA.Contains(player) { listFinal.Add(player) } } However, is there a more optimal way to do this instead of searching listA for each element in listB?

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• Get list of Unique many-to-many records from a queryset

  - by rsp

  My models: class Order(models.Model): ordered_by = models.ForeignKey(User) reasons = models.ManyToManyField(Reason) class Reason(models.Model): description = models.CharField() Basically a user creates an order and gives reasons for that order. ie, john has two orders (one for pencils because he is out AND because he doesn't like his current stock. a second order for pens because he is out). I want to print a list out of all reasons a user has placed his orders. So under john, it should print "he is out", "he doesn't like his current stock"; those two lines only. If I simply select all of john's orders, iterate through them and print out their "reasons" it'll print "he is out", "he doesn't like his current stock" and then "he is out" again. I don't want these duplicate values. How do I select a list of his reasons for ALL his orders so that the list has all unique rows?

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• Computing unique index for every poker starting hand

  - by Aly

  As there are 52 cards in a deck we know there are 52 choose 2 = 1326 distinct matchups, however in preflop poker this can be bucketed into 169 different hands such as AK offsuit and AK suited as whether it is A hearts K hearts or A spade K spades it makes no difference preflop. My question is, is there a nice mathematical property in which I can uniquely index each of these 169 hands (from 0 to 168 preferably). I am trying to create a look up table as a double[][] = new double [169][169] but have no way of changing a hand representation such as AKs (an Ace and a King of the same suit) to a unique index in this array.

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• jQuery Toggle with multiple unique DIVs?

  - by tony noriega

  I am using jQuery toggle with a link and a div. I will eventually have approx. 50 divs i want to toggle, and instead of creating a new function for each one, is there a way i can create a class and have it read unique ID's for each div? (if that makes sense) For instance, i will have A1, A2, A3, B1, B2, B3..e.tc.. $(document).ready(function() { $('#slickbox').hide(); $('a#slick-toggleA1').click(function() { $('#A1').toggle(300); return false; }); });

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• How do I create a check constraint?

  - by Zack Peterson

  Please imagine this small database... Diagram Tables Volunteer Event Shift EventVolunteer ========= ===== ===== ============== Id Id Id EventId Name Name EventId VolunteerId Email Location VolunteerId Phone Day Description Comment Description Start End Associations Volunteers may sign up for multiple events. Events may be staffed by multiple volunteers. An event may have multiple shifts. A shift belongs to only a single event. A shift may be staffed by only a single volunteer. A volunteer may staff multiple shifts. Check Constraints Can I create a check constraint to enforce that no shift is staffed by a volunteer that's not signed up for that shift's event? Can I create a check constraint to enforce that two overlapping shifts are never staffed by the same volunteer?

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• Algorithm to generate a list of unique combinations based on a list of numbers

  - by ross

  I would like to efficiently generate a unique list of combinations of numbers based on a starting list of numbers. example start list = [1,2,3,4,5] but the algorithm should work for [1,2,3...n] result = [1],[2],[3],[4],[5] [1,2],[1,3],[1,4],[1,5] [1,2,3],[1,2,4],[1,2,5] [1,3,4],[1,3,5],[1,4,5] [2,3],[2,4],[2,5] [2,3,4],[2,3,5] [3,4],[3,5] [3,4,5] [4,5] Note. I don't want duplicate combinations, although I could live with them, eg in the above example I don't really need the combination [1,3,2] because it already present as [1,2,3]

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• Unique identifiers for users

  - by Christopher McCann

  If I have a table of a hundred users normally I would just set up an auto-increment userID column as the primary key. But if suddenly we have a million users or 5 million users then that becomes really difficult because I would want to start becoming more distributed in which case an auto-increment primary key would be useless as each node would be creating the same primary keys. Is the solution to this to use natural primary keys? I am having a real hard time thinking of a natural primary key for this bunch of users. The problem is they are all young people so they do not have national insurance numbers or any other unique identifier I can think of. I could create a multi-column primary key but there is still a chance, however miniscule of duplicates occurring. Does anyone know of a solution? Thanks

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• Generating unique N-valued key

  - by Bar

  Hi, StackOverflow! I want to generate unique random, N-valued key. This key can contain numbers and latin characters, i.e. A-Za-z0-9. The only solution I am thinking about is something like this (pseudocode): key = ""; smb = "ABC…abc…0123456789"; // allowed symbols for (i = 0; i < N; i++) { key += smb[rnd(0, smb.length() - 1)]; // select symbol at random position } Is there any better solution? What can you suggest? TIA, Michael.

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• How to assign default values and define unique keys in Entity Framework 4 Designer

  - by csharpnoob

  Hello, I've had a look at the Entity Framework 4. While generating code for the SQL Server 2008 I came to the point where I want to define some default values for some fields. how to define in the designer for a Created DateTime Field the DateTime.Now default value? - Error 54: Default value (DateTime.Now) is not valid for DateTime. The value must be in the form 'yyyy-MM-dd HH:mm:ss.fffZ' how to make for code generation a string Field unique. Like E-Mail or Username can exists only once in the table. I've search alot in the internet and also checked my books Pro Entity Framework 4.0 and Programming Entity Framework. But none of them seems to come up with the default value issue, or using sql commands as default values for database generation. Another thing is, how to prevent on database generation always from droping tables? Instead i want to append non existing fields and keep the data. Thanks for any suggestions.

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• MySQL ignores the NOT NULL constraint

  - by Marga Keuvelaar

  I have created a table with NOT NULL constraints on some columns in MySQL. Then in PHP I wrote a script to insert data, with an insert query. When I omit one of the NOT NULL columns in this insert statement I would expect an error message from MySQL, and I would expect my script to fail. Instead, MySQL inserts empty strings in the NOT NULL fields. In other omitted fields the data is NULL, which is fine. Could someone tell me what I did wrong here? I'm using this table: CREATE TABLE IF NOT EXISTS tblCustomers ( cust_id int(11) NOT NULL AUTO_INCREMENT, custname varchar(50) NOT NULL, company varchar(50), phone varchar(50), email varchar(50) NOT NULL, country varchar(50) NOT NULL, ... date_added timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP, PRIMARY KEY (cust_id) ) ; And this insert statement: $sql = "INSERT INTO tblCustomers (custname,company) VALUES ('".$customerName."','".$_POST["CustomerCompany"]."')"; $res = mysqli_query($mysqli, $sql);

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• Template metaprogram converting type to unique number

  - by daramarak

  I just started playing with metaprogramming and I am working on different tasks just to explore the domain. One of these was to generate a unique integer and map it to type, like below: int myInt = TypeInt<AClass>::value; I want to know if this is at all possible, and in that case how. Because although I have learned much about exploring this subject I still have failed to come up with an answer. (P.S. A yes/no answer is much more gratifying than a c++ solution that doesn't use metaprogramming, as this is the domain that I am exploring)

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• spl_object_hash for PHP < 5.2 (unique ID for object instances)

  - by Rowan

  I'm trying to get unique IDs for object instances in PHP 5+. The function, spl_object_hash() is available from PHP 5.2 but I'm wondering if there's a workaround for older versions. There are a couple of functions in the comments on php.net but they're not working for me. The first (simplified): function spl_object_hash($object){ if (is_object($object)){ return md5((string)$object); } return null; } does not work with native objects (such as DOMDocument), and the second: function spl_object_hash($object){ if (is_object($object)){ ob_start(); var_dump($object); $dump = ob_get_contents(); ob_end_clean(); if (preg_match('/^object\(([a-z0-9_]+)\)\#(\d)+/i', $dump, $match)) { return md5($match[1] . $match[2]); } } return null; } looks like it could be a major performance buster! Does anybody have anything up their sleeve?

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• How to display unique success messages on jquery form validation

  - by mastah

  Hi guys, hope you can help me on this one, I'm currently using this: jQuery plugin:validation (Homepage) I've been reading related questions here, but this one is the closest get. http://stackoverflow.com/questions/1863448/jquery-validation-on-success from the plugin's documentation http://docs.jquery.com/Plugins/Validation/validate#toption success String, Callback If specified, the error label is displayed to show a valid element. If a String is given, its added as a class to the label. If a Function is given, its called with the label (as a jQuery object) as its only argument. That can be used to add a text like "ok!". Currently I'm only object given to me is the label, and I can only add text to it. Now what I want is to have unique success message. For example: username field will have a success message: 'username okay!' email = 'email seems right' something along those lines, instead of displaying just one generic success message on all the fields. Thanks in advanced :)

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