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  • Should I use formal methods on my software project?

    - by Michael
    Our client wants us to build a web-based, rich internet application for gathering software requirements. Basically it's a web-based case tool that follows a specific process for getting requirements from stakeholders. I'm the project manager and we're still in the early phases of the project. I've been thinking about using formal methods to help clarify the requirements for the tool for both my client and the developers. By formal methods I mean some form of modeling, possibly something mathematically-based. Some of the things I've read about and are considering include Z (http://en.wikipedia.org/wiki/Z_notation), state machines, UML 2.0 (possibly with extensions such as OCL), Petri nets, and some coding-level stuff like contracts and pre and post conditions. Is there anything else I should consider? The developers are experienced but depending on the formalism used they may have to learn some math. I'm trying to determine whether it's worth while for me to use formal methods on this project and if so, to what extent. I know "it depends" so the most helpful answers for me is a yes/no and supporting arguments. Would you use formal methods if you were on this project?

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  • How To Deal With Terrible Design Decisions

    - by splatto
    I'm a consultant at one company. There is another consultant who is a year older than me and has been here 3 months longer than I have, and a full time developer. The full-time developer is great. My concern is that I see the consultant making absolutely terrible design decisions. For example, M:M relationships are being stored in the database as a comma-delimited string rather than using a conjunction table to hold the relationships. For example, consider two tables, Car and Property: Car records: Camry Volvo Mercedes Property records: Spare Tire Satellite Radio Ipod Support Standard Rather than making a table CarProperties to represent this, he has made a "Property" attribute on the Car table whose data looks like "1,3,7,13,19,25," I hate how this decision and others are affecting the quality of my code. We have butted heads over this design three times in the past two months since I've been here. He asked me why my suggestion was better, and I responded that our database would be eliminating redundant data by converting to a higher normal form. I explained that this design flaw in particular is discussed and discouraged in entry level college programs, and he responded with a shot at me saying that these comma-separated-value database properties are taught when you do your masters (which neither of us have). Needless to say, he became very upset and demanded I apologize for criticizing his work, which I did in the interest of not wanting to be the consultant to create office drama. Our project manager is focused on delivering a product ASAP and is a very strong personality - Suggesting to him at this point that we spend some time to do this right will set him off. There is a strong likelihood that both of our contracts will be extended to work on a second project coming up. How will I be able to exert dominant influence over the design of the system and the data model to ensure that such terrible mistakes are not repeated in the next project? A glimpse at the dynamics: I can be a strong personality if I don't measure myself. The other consultant is not a strong personality, is a poor communicator, is quite stubborn and thinks he is better than everyone else. The project manager is an extremely strong personality who is focused on releasing tomorrow's product yesterday. The full-time developer is very laid back and easy going, a very effective communicator, but is someone who will accept bad design if it means not rocking the boat. Code reviews or anything else that takes "time" will be out of the question - there is no way our PM will be sold on such a thing by anybody.

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  • Make MySQL database replication always use the most free node?

    - by Chad Johnson
    We started using Multi-Master Replication Manager for MySQL, and I am wondering whether it is possible to to treat this setup like multi-symmetric processing: a process pops off the process queue, and the node (in this case a server) that is most free is selected for the job. It seems that what happens is, the service switches to a slave ONLY when it mysqld crashes or goes away. Is there a way to make database replication for MySQL act in more of a distributed manner? Maybe there is other software besides MMM that can do this? Is there a way to switch the reader role to another server whene mysqld slows down (rather than just when it fails)?

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  • database design help for game / user levels / progress

    - by sprugman
    Sorry this got long and all prose-y. I'm creating my first truly gamified web app and could use some help thinking about how to structure the data. The Set-up Users need to accomplish tasks in each of several categories before they can move up a level. I've got my Users, Tasks, and Categories tables, and a UserTasks table which joins the three. ("User 3 has added Task 42 in Category 8. Now they've completed it.") That's all fine and working wonderfully. The Challenge I'm not sure of the best way to track the progress in the individual categories toward each level. The "business" rules are: You have to achieve a certain number of points in each category to move up. If you get the number of points needed in Cat 8, but still have other work to do to complete the level, any new Cat 8 points count toward your overall score, but don't "roll over" into the next level. The number of Categories is small (five currently) and unlikely to change often, but by no means absolutely fixed. The number of points needed to level-up will vary per level, probably by a formula, or perhaps a lookup table. So the challenge is to track each user's progress toward the next level in each category. I've thought of a few potential approaches: Possible Solutions Add a column to the users table for each category and reset them all to zero each time a user levels-up. Have a separate UserProgress table with a row for each category for each user and the number of points they have. (Basically a Many-to-Many version of #1.) Add a userLevel column to the UserTasks table and use that to derive their progress with some kind of SUM statement. Their current level will be a simple int in the User table. Pros & Cons (1) seems like by far the most straightforward, but it's also the least flexible. Perhaps I could use a naming convention based on the category ids to help overcome some of that. (With code like "select cats; for each cat, get the value from Users.progress_{cat.id}.") It's also the one where I lose the most data -- I won't know which points counted toward leveling up. I don't have a need in mind for that, so maybe I don't care about that. (2) seems complicated: every time I add or subtract a user or a category, I have to maintain the other table. I foresee synchronization challenges. (3) Is somewhere in between -- cleaner than #2, but less intuitive than #1. In order to find out where a user is, I'd have mildly complex SQL like: SELECT categoryId, SUM(points) from UserTasks WHERE userId={user.id} & countsTowardLevel={user.level} groupBy categoryId Hmm... that doesn't seem so bad. I think I'm talking myself into #3 here, but would love any input, advice or other ideas. P.S. Sorry for the cross-post. I wrote this up on SO and then remembered that there was a game dev-focused one. Curious to see if I get different answers one place than the other....

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  • PostgreSQL data diff

    - by skanatek
    Note: this question is not about syncing database schema/structure Problem In my web application I have a PostgreSQL database server (PGS) and a (separate machine) business logic server (BLS) which regularly (every minute or two) queries 'SELECT ALL' against PGS. The problem is that the 'SELECT ALL' query can easily return 50-200 MB each time. It is obvious that it would be not so good architecture-wise to transfer so much data so frequently over the web. Possible solution What I would like to do is to run some diff tool on PGS and compare the new query with the previous query (all this should be done on PGS). Once the comparison is done I would like to get a dump from PGS and transfer it to BLS. I expect that a diff-based dump would be much, much smaller than the whole 'SELECT ALL' query. Question Is there any data diff tool for PostgreSQL that can do diffs that compare PostgreSQL data between 2 tables or 2 dumps? Note: I would prefer some open-source software tool.

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  • Drupal on IIS - Cannot connect to the database

    - by Patrick
    hi, I've hard time to make Drupal work on IIS Microsoft server. I've succesfully run Joomla on the same server so I'm pretty sure the following information are correct: host: localhost user: user pass: pass databaseName = servername_databasename I've set the following line in settings.php file: $db_url = 'mysql://user:password@localhost/servername_databasename'; but what I get is this: If you are the maintainer of this site, please check your database settings in the settings.php file and ensure that your hosting provider's database server is running. For more help, see the handbook, or contact your hosting provider. I don't get any other error message such as: database doesn't exist, user/pass wrong.. just this. The database is running, I can access with phpmyadmin. I've tried both "mysql" and "mysqli". The host is a private server (IIS Microsoft), the database is Mysql The database and website files upload have also been succesfull.. so I dunno what to do to fix this issue. thanks

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  • Does semi-normalization exist as a concept? Is it "normalized"?

    - by Gracchus
    If you don't mind, a tldr on my experience: My experience tldr I have an application that's heavily dependent upon uncertainty, a bane to database design. I tried to normalize it as best as I could according to the capabilities of my database of choice, but a "simple" query took 50ms to read. Nosql appeals to me, but I can't trust myself with it, and besides, normalization has cut down my debugging time immensely over and over. Instead of 100% normalization, I made semi-redundant 1:1 tables with very wide primary keys and equivalent foreign keys. Read times dropped to a few ms, and write times barely degraded. The semi-normalized point Given this reality, that anyone who's tried to rely upon views of fully normalized data is aware of, is this concept codified? Is it as simple as having wide unique and foreign keys, or are there any hidden secrets to this technique? Or is uncertainty merely a special case that has extremely limited application and can be left on the ash heap?

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  • Extracting the Layout of all the Data Forms from the Relational Database

    - by RahulS
    Today I came across a question from one of our clients that: "what members are used on each data form WITHOUT having to go through the report generated out of our Planning app". We worked with client on this and reached to a simple query. All the form related information is stored in the following tables: HSP_FORM HSP_FORMOBJ_DEF HSP_FORMOBJ_DEF_MBR HSP_FORM_ATTRIBUTES HSP_FORM_CALCS HSP_FORM_DV_CONDITION HSP_FORM_DV_PM_RULE HSP_FORM_DV_RULE HSP_FORM_DV_USER_IN_PM_RULE HSP_FORM_LAYOUT HSP_FORM_MENUS HSP_FORM_VARIABLES If we want to retrieve just the members included, we can concentrate on: HSP_OBJECT to get the Object_ID for form, Object_Type is 7 for forms. (Ex: Select * from HSP_OBJECT where OBJECT_TYPE = 7) HSP_FORMOBJ_DEF Find the OBJDEF_ID for a particular form HSP_FORMOBJ_DEF_MBR Use the above OBJDEF_ID to find the members: Here the Mbr_ID is the Id of the member and Query_Type is the Function like Idesc, Level0 etc and Sequce is you sequence, And the final table we can use is HSP_FORM_LAYOUT: Layout_Type: 0->Pov 1-> Page, 2->Row, 3->Col, DIM_ID is the dimension ID and Ordinal is position. Here is the Query: SELECT HSP_OBJECT.OBJECT_NAME AS 'Form',  HSP_OBJECT_2.OBJECT_NAME AS 'Dimension',  HSP_OBJECT_1.OBJECT_NAME AS 'Member',  HSP_FORMOBJ_DEF_MBR.QUERY_TYPE FROM  <DatabaseName>.dbo.HSP_FORM_LAYOUT HSP_FORM_LAYOUT,  <DatabaseName>.dbo.HSP_FORMOBJ_DEF HSP_FORMOBJ_DEF,  <DatabaseName>.dbo.HSP_FORMOBJ_DEF_MBR HSP_FORMOBJ_DEF_MBR,  <DatabaseName>.dbo.HSP_MEMBER HSP_MEMBER,  <DatabaseName>.dbo.HSP_OBJECT HSP_OBJECT,  <DatabaseName>.dbo.HSP_OBJECT HSP_OBJECT_1,  <DatabaseName>.dbo.HSP_OBJECT HSP_OBJECT_2 WHERE  HSP_OBJECT.OBJECT_ID = HSP_FORMOBJ_DEF.FORM_ID AND  HSP_FORMOBJ_DEF_MBR.OBJDEF_ID = HSP_FORMOBJ_DEF.OBJDEF_ID AND  HSP_MEMBER.MEMBER_ID = HSP_FORMOBJ_DEF_MBR.MBR_ID AND  HSP_OBJECT_1.OBJECT_ID = HSP_MEMBER.MEMBER_ID AND  HSP_OBJECT_2.OBJECT_ID = HSP_MEMBER.DIM_ID AND  HSP_FORM_LAYOUT.DIM_ID = HSP_MEMBER.DIM_ID AND  HSP_FORM_LAYOUT.FORM_ID = HSP_FORMOBJ_DEF.FORM_ID AND  ((HSP_OBJECT.OBJECT_TYPE=7)) ORDER BY HSP_OBJECT.OBJECT_NAME  Concentrate on Test1 data form and Actual Layout of it as follows: Corresponding Query_type for few of the functions: 9  for Idesc, 3  for Ancestors, -9 for ILvl0Des, 8  for Desc, 4  for IAncestors Its just a basic idea you can do lot on the basis of this. Cheers..!!! Rahul S. http://www.facebook.com/pages/HyperionPlanning/117320818374228

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  • How to insert/update multiple record into SQLite database in a single query.

    - by TuanCM
    Hi Guy. Is it possible to insert/update multiple record in SQLite database using EGODatabase wrapper. If I'm correct I think we can do it with FMDatabase by wrapping it between [db beginTransaction] and [db commit]. I wonder if we can do the same thing by using EGODatabase. Following is the code sample from FMDatabase project: [db beginTransaction]; i = 0; while (i++ < 20) { [db executeUpdate:@"insert into test (a, b, c, d, e) values (?, ?, ?, ?, ?)" , @"hi again'", // look! I put in a ', and I'm not escaping it! [NSString stringWithFormat:@"number %d", i], [NSNumber numberWithInt:i], [NSDate date], [NSNumber numberWithFloat:2.2f]]; } [db commit];

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  • How many address fields would you use for a UK database?

    - by Draemon
    Address records are probably used in most database, but I've seen a number of slightly different sets of fields used to store them. The number of fields seems to vary from 3-7, and sometimes all fields are simple labelled address1..addressN, other times given specific meaning (town, city, etc). This is UK specific, though I'm open to comments about the rest of the world too. Here you need the first line of the address (actually just the number) and the post code to identify the address - everything else is mostly an added bonus. I'm currently favouring: Address 1 Address 2 Address 3 Town County Post Code We could add Country if we ever needed it (unlikely). What do you think? Is this too little, too much?

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  • Synchronise Database between servers via php [closed]

    - by Emmanuel
    Hi Guys, I'm needing to synchronise two mysql databases between different servers on a regular basis, by a client-initiated interface. I've been doing it by remote MYSQL connection, and adding the IP of the servers to the whitelist for MYSQL remote connections. Problem is however, that the client has a dynamic IP, so as soon as it changes they can no longer sync. So I'm trying to find an alternative way of synchronising the two databases via some sort of secure php script.

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  • In native C++, how does one use a SqlCe .sdf database?

    - by Omer Sabic
    Is there a simple way, without .NET? I've found some libraries but none for SqlCe 3.5. There is http://sqlcehelper.codeplex.com/ but it's far from done, since a major feature like using a password is not yet implemented. I've looked at the source and it uses OLEdb to handle the database. The offical Microsoft Northwind example (that is shipped with SQL Compact 3.1, but not with 3.5) also doesn't work, I've tried setting it up with no success. Actually I don't have a sample working code. Was anyone able to set it up paired with a passworded .sdf? What are the alternatives? Thanks.

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  • uploading image & getting back from database

    - by Anup Prakash
    Putting a set of code which is pushing image to database and fetching back from database: <!-- <?php error_reporting(0); // Connect to database $errmsg = ""; if (! @mysql_connect("localhost","root","")) { $errmsg = "Cannot connect to database"; } @mysql_select_db("test"); $q = <<<CREATE create table image ( pid int primary key not null auto_increment, title text, imgdata longblob, friend text) CREATE; @mysql_query($q); // Insert any new image into database if (isset($_POST['submit'])) { move_uploaded_file($_FILES['imagefile']['tmp_name'],"latest.img"); $instr = fopen("latest.img","rb"); $image = addslashes(fread($instr,filesize("latest.img"))); if (strlen($instr) < 149000) { $image_query="insert into image (title, imgdata,friend) values (\"". $_REQUEST['title']. "\", \"". $image. "\",'".$_REQUEST['friend']."')"; mysql_query ($image_query) or die("query error"); } else { $errmsg = "Too large!"; } $resultbytes=''; // Find out about latest image $query = "select * from image where pid=1"; $result = @mysql_query("$query"); $resultrow = @mysql_fetch_assoc($result); $gotten = @mysql_query("select * from image order by pid desc limit 1"); if ($row = @mysql_fetch_assoc($gotten)) { $title = htmlspecialchars($row[title]); $bytes = $row[imgdata]; $resultbytes = $row[imgdata]; $friend=$row[friend]; } else { $errmsg = "There is no image in the database yet"; $title = "no database image available"; // Put up a picture of our training centre $instr = fopen("../wellimg/ctco.jpg","rb"); $bytes = fread($instr,filesize("../wellimg/ctco.jpg")); } if ($resultbytes!='') { echo $resultbytes; } } ?> <html> <head> <title>Upload an image to a database</title> </head> <body bgcolor="#FFFF66"> <form enctype="multipart/form-data" name="file_upload" method="post"> <center> <div id="image" align="center"> <h2>Heres the latest picture</h2> <font color=red><?php echo $errmsg; ?></font> <b><?php echo $title ?></center> </div> <hr> <h2>Please upload a new picture and title</h2> <table align="center"> <tr> <td>Select image to upload: </td> <td><input type="file" name="imagefile"></td> </tr> <tr> <td>Enter the title for picture: </td> <td><input type="text" name="title"></td> </tr> <tr> <td>Enter your friend's name:</td> <td><input type="text" name="friend"></td> </tr> <tr> <td><input type="submit" name="submit" value="submit"></td> <td></td> </tr> </table> </form> </body> </html> --> Above set of code has one problem. The problem is whenever i pressing the "submit" button. It is just displaying the image on a page. But it is leaving all the html codes. even any new line message after the // Printing image on browser echo $resultbytes; //************************// So, for this i put this set of code in html tag: This is other sample code: <!-- <?php error_reporting(0); // Connect to database $errmsg = ""; if (! @mysql_connect("localhost","root","")) { $errmsg = "Cannot connect to database"; } @mysql_select_db("test"); $q = <<<CREATE create table image ( pid int primary key not null auto_increment, title text, imgdata longblob, friend text) CREATE; @mysql_query($q); // Insert any new image into database if (isset($_POST['submit'])) { move_uploaded_file($_FILES['imagefile']['tmp_name'],"latest.img"); $instr = fopen("latest.img","rb"); $image = addslashes(fread($instr,filesize("latest.img"))); if (strlen($instr) < 149000) { $image_query="insert into image (title, imgdata,friend) values (\"". $_REQUEST['title']. "\", \"". $image. "\",'".$_REQUEST['friend']."')"; mysql_query ($image_query) or die("query error"); } else { $errmsg = "Too large!"; } $resultbytes=''; // Find out about latest image $query = "select * from image where pid=1"; $result = @mysql_query("$query"); $resultrow = @mysql_fetch_assoc($result); $gotten = @mysql_query("select * from image order by pid desc limit 1"); if ($row = @mysql_fetch_assoc($gotten)) { $title = htmlspecialchars($row[title]); $bytes = $row[imgdata]; $resultbytes = $row[imgdata]; $friend=$row[friend]; } else { $errmsg = "There is no image in the database yet"; $title = "no database image available"; // Put up a picture of our training centre $instr = fopen("../wellimg/ctco.jpg","rb"); $bytes = fread($instr,filesize("../wellimg/ctco.jpg")); } } ?> <html> <head> <title>Upload an image to a database</title> </head> <body bgcolor="#FFFF66"> <form enctype="multipart/form-data" name="file_upload" method="post"> <center> <div id="image" align="center"> <h2>Heres the latest picture</h2> <?php if ($resultbytes!='') { // Printing image on browser echo $resultbytes; } ?> <font color=red><?php echo $errmsg; ?></font> <b><?php echo $title ?></center> </div> <hr> <h2>Please upload a new picture and title</h2> <table align="center"> <tr> <td>Select image to upload: </td> <td><input type="file" name="imagefile"></td> </tr> <tr> <td>Enter the title for picture: </td> <td><input type="text" name="title"></td> </tr> <tr> <td>Enter your friend's name:</td> <td><input type="text" name="friend"></td> </tr> <tr> <td><input type="submit" name="submit" value="submit"></td> <td></td> </tr> </table> </form> </body> </html> --> ** But in this It is showing the image in format of special charaters and digits. 1) So, Please help me to print the image with some HTML code. So that i can print it in my form to display the image. 2) Is there any way to convert the database image into real image, so that i can store it into my hard-disk and call it from tag? Please help me.

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  • Do you use Styrofoam balls to model your systems?

    - by Nick D
    [Objective-C] Do you still use Styrofoam balls to model your systems, where each ball represents a class? Tom Love: We do, actually. We've also done a 3D animation version of it, which we found to be nowhere near as useful as the Styrofoam balls. There's something about a physical, conspicuous structure hanging from the ceiling right in the middle of a development project that's regularly updated to provide not only the structure of the system that you're building, but also the current status of each one of the classes. We've done it on 19 projects the last time I've counted. One of them was 1,856 classes, which is big - actually, probably bigger than it should be. It was a big commercial project, so it needed to be somewhat big. Masterminds of Programming It is the first time I've read or heard about using styrofoam balls to model classes. Is that a commonly used technique? And, how does that sort of modeling help us to design better the system? If you have any photos to share which can show us how the classes are represented it'd be great!

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  • SIMD Extensions for the Database Storage Engine

    - by jchang
    For the last 15 years, Intel and AMD have been progressively adding special purpose extensions to their processor architectures. The extensions mostly pertain to vector operations with Single Instruction, Multiple Data (SIMD) concept. The reasoning was that achieving significant performance improvement over each successive generation for the general purpose elements had become extraordinarily difficult. On the other hand, SIMD performance could be significantly improved with special purpose registers...(read more)

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  • SSMS Built in Reports for Server and Database Monitoring

    - by GrumpyOldDBA
    This is a long post which I hope will format correctly – I’ve placed a pdf version for download here  http://www.grumpyolddba.co.uk/sql2008/ssmsreports_grumpyolddba.pdf I sometimes discover that the built in reports for SQL Server within SSMS are an unknown, sometimes this is because not all the right components were installed during the server build, other times is because generally there’s never been great reporting for the DBA from the SQL Team so no-one expects to find anything useful for...(read more)

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  • SQL Server 2005: When copy table structure to other database "CONSTRAINT" keywords lost

    - by StreamT
    Snippet of original table: CREATE TABLE [dbo].[Batch]( [CustomerDepositMade] [money] NOT NULL CONSTRAINT [DF_Batch_CustomerDepositMade] DEFAULT (0) Snippet of copied table: CREATE TABLE [dbo].[Batch]( [CustomerDepositMade] [money] NOT NULL, Code for copy database: Server server = new Server(SourceSQLServer); Database database = server.Databases[SourceDatabase]; Transfer transfer = new Transfer(database); transfer.CopyAllObjects = true; transfer.CopySchema = true; transfer.CopyData = false; transfer.DropDestinationObjectsFirst = true; transfer.DestinationServer = DestinationSQLServer; transfer.CreateTargetDatabase = true; Database ddatabase = new Database(server, DestinationDatabase); ddatabase.Create(); transfer.DestinationDatabase = DestinationDatabase; transfer.Options.IncludeIfNotExists = true; transfer.TransferData();

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  • How to merge data from two separate access 2007 databases

    - by DiegoMaK
    Hi, I have two identical databases with same structure, database a in computer a and database b in computer b. The data of database a*(a.accdb)* and database b*(b.accdb)* are different. then in database a i have for example ID:1, 2, 3 and in database B i Have ID:4,5,6 Then i need merge these databases data in only one database(a or b, doesn't matter) so the final database looks like. ID:1,2,3,4,5,6 I search an easy way to do this. because i have many tables. and do this by union query is so tedious. I search for example for a backup option for only data without scheme as in postgreSQl or many others RDBMS, but i don't see this options in access 2007. pd:only just table could be have duplicate values(I guess that pk doesn't allow copy a duplicate value and all others values will be copied well). if i wrong please correct me. thanks for your help.

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