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  • Write a SQL Query to replace values and include all the Dates.

    - by VJ
    Well I have this - Table DimDate- Date Table Employee- Id,Name,Points,Date Now the Employee table has points for everyday unless they did not come...so the Date does not have all the Dates entries... I mean for e.g in a week he did not come for 2 days the Employee table has only 5 rows...so I have this dimdate table which has all the dates till 2050 which I want to join with and add Zeros for the dates he does not have points. So I have written this query but does not work - Select E.EmployeeId,D.Date,isNull(E.Points,0) from DimDate D left join Employee E on D.Date between '01-01-2009'and '06-01-2009' where E.EmployeeId=1 The above query give multiple dates and I tried group by on Date but does not work.

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  • Given a linked list of numbers. Swap every 2 adjacent links.

    - by Learner
    Given a linked list of numbers. Swap every 2 adjacent links. For eg if a linked list given to you is- a-b-c-d-e-f O/p expected- b-a-d-c-f-e Every 2 alternate links have to be swapped. I have written a solution here. Can you suggest me some other solution. Can you comment on my solution and help me better write it? void SwapAdjacentNodes (Node head) { if (head == null) return; if (head.next == null) return; Node curr = head; Node next = curr.Next; Node temp = next.Next; while (true) { temp = next.Next; next.Next = curr; curr.Next = temp; if (curr.Next != null) curr = curr.Next; else break; if (curr.Next.Next!=null) next = curr.Next.Next; else break; } }

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  • How to guard against memory leaks?

    - by just_wes
    I was recently interviewing for a C++ position, and I was asked how I guard against creating memory leaks. I know I didn't give a satisfactory answer to that question, so I'm throwing it to you guys. What are the best ways to guard against memory leaks? Thanks!

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  • Can I delete a differential backup from SQL Server 2005?

    - by BlueMonkMN
    I often like to create backups when testing the software I work on, and will sometimes create a differential backup if I want to be able to get back to multiple previous states. However, sometimes I realize that I forgot one thing I wanted to include in a differential backup, or I no longer need a previous differential backup. Sometimes I simply want to create a new scenario from the original base image and start working with a new series of differential backups. So I'd like to be able to delete some older differential backups so I don't get confused about which ones I'm using. But I can't find any way to delete just the differential backups, selectively or all at once.

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  • SQL query select from table and group on other column...

    - by scaryjones
    I'm phrasing the question title poorly as I'm not sure what to call what I'm trying to do but it really should be simple. I've a link / join table with two ID columns. I want to run a check before saving new rows to the table. The user can save attributes through a webpage but I need to check that the same combination doesn't exist before saving it. With one record it's easy as obviously you just check if that attributeId is already in the table, if it is don't allow them to save it again. However, if the user chooses a combination of that attribute and another one then they should be allowed to save it. Here's an image of what I mean: So if a user now tried to save an attribute with ID of 1 it will stop them, but I need it to also stop them if they tried ID's of 1, 10 so long as both 1 and 10 had the same productAttributeId. I'm confusing this in my explanation but I'm hoping the image will clarify what I need to do. This should be simple so I presume I'm missing something.

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  • Sql Server 2000 Stored Procedure Prevents Parallelism or something?

    - by user187305
    I have a huge disgusting stored procedure that wasn't slow a couple months ago, but now is. I barely know what this thing does and I am in no way interested in rewriting it. I do know that if I take the body of the stored procedure and then declare/set the values of the parameters and run it in query analyzer that it runs more than 20x faster. From the internet, I've read that this is probably due to a bad cached query plan. So, I've tried running the sp with "WITH RECOMPILE" after the EXEC and I've also tried putting the "WITH RECOMPLE" inside the sp, but neither of those helped even a little bit. When I look at the execution plan of the sp vs the query, the biggest difference is that the sp has "Parallelism" operations all over the place and the query doesn't have any. Can this be the cause of the difference in speeds? Thank you, any ideas would be great... I'm stuck.

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  • Shuffle array variables in a pre-specified order, without using extra memory of "size of input array"

    - by Eternal Learner
    Input : A[4] = {0,4,-1,1000} - Actual Array P[4] = {1,0,3,2} - Order to be reshuffled Output: A[4] = {4,0,1000,-1} Condition : Don't use an additional array as memory. Can use an extra variable or two. Problem : I have the below program in C++, but this fails for certain inputs of array P. #include<iostream> using namespace std; void swap(int *a_r,int *r) { int temp = *r; *r = *a_r; *a_r = temp; } int main() { int A[4] = {0,4,-1,1000}; int P[4] = {3,0,1,2}; int value = A[0] , dest = P[0]; for(int i=0; i<4;i++) { swap(&A[dest],&value); dest = P[dest]; } for(int i=0;i<4;i++) cout<<A[i]<<" "; }

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  • Add to exisiting db values, rather than overwrite - PDO

    - by sam
    Im trying to add to existing decimal value in table, for which im using the sql below: UPDATE Funds SET Funds = Funds + :funds WHERE id = :id Im using a pdo class to handle my db calls, with the method below being used to update the db, but i couldnt figure out how to amend it to output the above query, any ideas ? public function add_to_values($table, $info, $where, $bind="") { $fields = $this->filter($table, $info); $fieldSize = sizeof($fields); $sql = "UPDATE " . $table . " SET "; for($f = 0; $f < $fieldSize; ++$f) { if($f > 0) $sql .= ", "; $sql .= $fields[$f] . " = :update_" . $fields[$f]; } $sql .= " WHERE " . $where . ";"; $bind = $this->cleanup($bind); foreach($fields as $field) $bind[":update_$field"] = $info[$field]; return $this->run($sql, $bind); }

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  • Why does this SQL work in VS but not in code?

    - by acidzombie24
    The line cmd.ExecuteNonQuery(); cmd.CommandText CREATE TRIGGER subscription_trig_0 ON subscription AFTER INSERT AS UPDATE user_data SET msg_count = msg_count + 1 FROM user_data JOIN INSERTED ON user_data.id = INSERTED.recipient; The exception: Incorrect syntax near the keyword 'TRIGGER'. Then using VS 2010, connected to the very same file (a mdf file) i run the query above and i get a success message.

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  • SQL Server: How to tell if a database is a system database?

    - by Vinko Vrsalovic
    I know that so far (until MSSQL 2005 at least), system databases are master, model, msdb and tempdb. Thing is, as far as I can tell, this is not guaranteed to be preserved in the future. And neither the sys.databases view nor the sys.sysdatabases view tell me if a database is considered as a system database. Is there someplace where this information (whether a database is considered a system database or not) can be obtained?

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  • [MS Access 2003 SQL] Switch is causing #error, why and how can I fix it...

    - by Chris
    I have 3 fields in my table: start, end (dates) and length (number, might be blank). My Aim is to calculate an end date using start and length where end doesn't exist... I have: SELECT Switch((g.length<>0) And IsDate(g.end),DateAdd("m",g.length,g.start)) AS field FROM table g If there is no start, end or length, Access displays blank - this is fine. If there is no end, but start and length are ok, the calculated date is shown - again fine. BUT If there is no end, or length, but a start exists, access displays #Error I don't understand why, and can't fix it, please help!

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  • I need help with a SQL query. Fetching an entry, it's most recent revision and it's fields.

    - by Tigger ate my dad
    Hi there, I'm building a CMS for my own needs, and finished planning my database layout. Basically I am abstracting all possible data-models into "sections" and all entries into one table. The final layout is as follows: Database diagram: I have yet to be allowed to post images, so here is a link to a diagram of my database. Entries (section_entries) are children of their section (sections). I save all edits to the entries in a new revision (section_entries_revisions), and also track revisions on the sections (section_revisions), in order to match the values of a revision, to the fields of the section that existed when the entry-revision was made. The section-revisions can have a number of fields (section_revision_fields) that define the attributes of entries in the section. There is a many-to-many relationship between the fields (section_revision_fields) and the entry-revisions (section_entry_revisions), that stores the values of the attributes defined by the section revision. Feel free to ask questions if the diagram is confusing. Now, this is the most complex SQL I've ever worked with, and the task of fetching my data is a little daunting. Basically what i want help with, is fetching an entry, when the only known variables are; section_id, section_entry_id. The query should fetch the most recent revision of that entry, and the section_revision model corresponding to section_revision_id in the section_entry_revisions table. It should also fetch the values of the fields in the section-revision. I was hoping for a query result, where there would be as many rows as fields in the section. Each row would contain the information of the entry and the section, and then information for one of the fields (e.g. each row corresponding to a field and it's value). I tried to explain the best I could. Again, feel free to ask questions if my description somehow lacking. I hope someone is up for the challenge. Best regards. :-)

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  • How to query by recent date and value in SQL?

    - by wsb3383
    I have a table with three columns: patient_id, obs_date, and weight_val. patient_id stores patient identification #, weight_val stores a weight value, and obs_date stores the date when the weight reading was taken. So, a patient can have many different weight readings at different dates. How do you write a query for: select all patients whose last weight reading is 120?

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  • Compare two integer arrays with same length

    - by meta
    [Description] Given two integer arrays with the same length. Design an algorithm which can judge whether they're the same, the definition of "same" is that, if these two arrays are in sorted order, the elements in corresponding position should be the same. [Example] <1 2 3 4> = <3 1 2 4> <1 2 3 4> != <3 4 1 1> [Limitation] The algorithm should require constant extra space, and O(n) running time.

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  • Why would SQL be very slow when doing updates?

    - by ooo
    Suddenly doing updates into a few tables have gotten 10 times slower than they used to be. What are some good recommendations to determine root cause and optimization? Could it be that indexing certain columns are causing updates to be slow? Any other recommendations? I guess more important than guesses would be help on the process of identifying the root cause or metrics around performance. Is there anything in Fluent NHibernate that you can use to help identify the root cause of performance issues?

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  • SQL -- How is DISTINCT so fast without an index?

    - by Jonathan
    Hi, I have a database with a table called 'links' with 600 million rows in it in SQLite. There are 2 columns in the database - a "src" column and a "dest" column. At present there are no indices. There are a fair number of common values between src and dest, but also a fair number of duplicated rows. The first thing I'm trying to do is remove all the duplicate rows, and then perform some additional processing on the results, however I've been encountering some weird issues. Firstly, SELECT * FROM links WHERE src=434923 AND dest=5010182. Now this returns one result fairly quickly and then takes quite a long time to run as I assume it's performing a tablescan on the rest of the 600m rows. However, if I do SELECT DISTINCT * FROM links, then it immediately starts returning rows really quickly. The question is: how is this possible?? Surely for each row, the row must be compared against all of the other rows in the table, but this would require a tablescan of the remaining rows in the table which SHOULD takes ages! Any ideas why SELECT DISTINCT is so much quicker than a standard SELECT?

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  • How can I sum a group of sums? SQL-Sever 2008

    - by billynomates
    I have a query with a sum in it like this: SELECT Table1.ID, SUM(Table2.[Number1] + Table2.[Number2]) AS SumColumn FROM Table1 INNER JOIN Table3 ON Table1.ID = Table3.ID INNER JOIN Table2 ON Table3.ID = Table2.ID WHERE (Table2.[Something] = 'Whatever') GROUP BY Table1.ID, Table2.[Number1] , Table2.[Number2] and it gives me a table like this: ID SumColumn 67 1 67 4 70 2 70 6 70 3 70 6 80 5 97 1 97 3 How can I make it give me a table like this, where the SumColumn is summed, grouped by the ID column? ID SumColumn 67 5 70 17 80 5 97 4 I cannot GROUP BY SumColumn because I get an error (Invalid column name 'SumColumn'.) COALESCE doesn't work either. Thanks in advance. EDIT: Just grouping by the ID gives me an error: [Number1, Number2 and the other column names that I'm selecting] is invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause.

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  • SQL grouping query question; evaluating a group of rows based on the value of one field.

    - by user324575
    I've got table vendorparts that lists all my parts and their vendor(s). Parts with multiple vendors have multiple records in this table. I'm trying to write a query that only returns the partid, and vendor of parts that do not have a default vendor assigned. Partid Vendor Defaultflag 1 A 1 2 B 0 2 C 0 3 D 0 3 E 0 3 F 1 4 G 0 I would like to return the following: Partid Vendor 2 A 2 B 4 G I'm obviously having issues with partid 3 and getting the query to see it as having a default vendor assigned.

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  • What constitutes explicit creation of entities in LINQ to SQL? What elegant "solutions" are there to

    - by Marcelo Zabani
    Hi SO, I've been having problems with the rather famous "Explicit construction of entity type '##' in query is not allowed." error. Now, for what I understand, this exists because if explicit construction of these objects were allowed, tracking changes to the database would be very complicated. So I ask: What constitutes the explicit creation of these objects? In other terms: Why can I do this: Product foo = new Product(); foo.productName = "Something"; But can't do this: var bar = (from item in myDataContext.Products select new Product { productName = item.productName }).ToList(); I think that when running the LINQ query, some kind of association is made between the objects selected and the table rows retrieved (and this is why newing a Product in the first snippet of code is no problem at all, because no associations were made). I, however, would like to understand this a little more in depth (and this is my first question to you, that is: what is the difference from one snippet of code to another). Now, I've heard of a few ways to attack this problem: 1) The creation of a class that inherits the linq class (or one that has the same properties) 2) Selecting anonymous objects And this leads me to my second question: If you chose one of the the two approaches above, which one did you choose and why? What other problems did your approach introduce? Are there any other approaches?

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  • Querying a smalldatetime's date and time seperately in SQL server?

    - by Kylee
    Imagine a table that has two fields, a smalltimedate and an int and about 1000 rows of data. What I'm attempting to do in query is to find the average of the INT field for rows between 3/3/2010 - 3/13/2010 and only if the entry is between 6:00am - 11:00pm. I tried between '2010-03-03 06:00 AND 2010-03-13 23:00' However that only restricts that very beginning and end times. I could do this with a loop but I'm going to need to have the same query run over much larger date ranges and this will quickly eat server resources. Is there a way to query date and time seperately?

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