Search Results

Search found 32641 results on 1306 pages for 'sql constraint and keys'.

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

Page 477/1306 | < Previous Page | 473 474 475 476 477 478 479 480 481 482 483 484  | Next Page >

  • FieldError when annotating over foreign keys

    - by X_9
    I have a models file that looks similar to the following: class WithDate(models.Model): adddedDate = models.DateTimeField(auto_now_add=True) modifiedDate = models.DateTimeField(auto_now=True) class Meta: abstract = True class Match(WithDate): ... class Notify(WithDate): matchId = models.ForeignKey(Match) headline = models.CharField(null=True, blank=True, max_length=10) For each Match I'm trying to get a count of notify records that have a headline. So my call looks like matchObjs = Match.objects.annotate(notifies_made=Count('notify__headline__isnull')) This keeps throwing a FieldError. I've simplified the query down to matchObjs = Match.objects.annotate(notifies_made=Count('notify')) And I still get the same FieldError... I've seen this work in other cases (other documentation, other SO questions like this one) but I can't figure out why I'm getting an error. The specific error that is returned is as follows: Cannot resolve keyword 'notify' into field. Choices are: (all fields from Match model) Does anyone have a clue as to why I can't get this annotation to work across tables? I'm baffled after looking at the other SO question and various Django docs where I've seen this done. Edit: I am using Django 1.1.1

    Read the article

  • Is there a way to give a subquery an alias in Oracle 10g SQL?

    - by Matt Pascoe
    Is there a way to give a subquery in Oracle 11g an alias like: select * from (select client_ref_id, request from some_table where message_type = 1) abc, (select client_ref_id, response from some_table where message_type = 2) defg where abc.client_ref_id = def.client_ref_id; Otherwise is there a way to join the two subqueries based on the client_ref_id. I realize there is a self join, but on the database I am running on a self join can take up to 5 min to complete (there is some extra logic in the actual query I am running but I have determined the self join is what is causing the issue). The individual subqueries only take a few seconds to complete by them selves. The self join query looks something like: select st.request, st1.request from some_table st, some_table st1 where st.client_ref_id = st1.client_ref_id;

    Read the article

  • LINQ Joins - Performance

    - by Meiscooldude
    I am curious on how exactly LINQ (not LINQ to SQL) is performing is joins behind the scenes in relation to how Sql Server performs joins. Sql Server before executing a query, generates an Execution Plan. The Execution Plan is basically an Expression Tree on what it believes is the best way to execute the query. Each node provides information on whether to do a Sort, Scan, Select, Join, ect. On a 'Join' node in our execution plan, we can see three possible algorithms; Hash Join, Merge Join, and Nested Loops Join. Sql Server will choose which algorithm to for each Join operation based on expected number of rows in Inner and Outer tables, what type of join we are doing (some algorithms don't support all types of joins), whether we need data ordered, and probably many other factors. Join Algorithms: Nested Loop Join: Best for small inputs, can be optimized with ordered inner table. Merge Join: Best for medium to large inputs sorted inputs, or an output that needs to be ordered. Hash Join: Best for medium to large inputs, can be parallelized to scale linearly. LINQ Query: DataTable firstTable, secondTable; ... var rows = from firstRow in firstTable.AsEnumerable () join secondRow in secondTable.AsEnumerable () on firstRow.Field<object> (randomObject.Property) equals secondRow.Field<object> (randomObject.Property) select new {firstRow, secondRow}; SQL Query: SELECT * FROM firstTable fT INNER JOIN secondTable sT ON fT.Property = sT.Property Sql Server might use a Nested Loop Join if it knows there are a small number of rows from each table, a merge join if it knows one of the tables has an index, and Hash join if it knows there are a lot of rows on either table and neither has an index. Does Linq choose its algorithm for joins? or does it always use one?

    Read the article

  • T-SQL: How to use GROUP BY and getting the value which excesses 60%?

    - by Torben H.
    Hello, sorry for the bad title, I don't know how to describe my problem. I have the following table: | ItemID | Date | ------------------------- | 1 | 01.01.10 | | 1 | 03.01.10 | | 1 | 05.01.10 | | 1 | 06.01.10 | | 1 | 10.01.10 | | 2 | 05.01.10 | | 2 | 10.01.10 | | 2 | 20.01.10 | Now I want to GROUP BY ItemID and for the date I want to get the value, which excesses 60%. What I mean is, that for item 1 I've five rows, so each have a percentage of 20% and for item 2 I've three row, so each have a percentage of 33,33%. So for item 1 I need the 3rd and for item 2 the 2nd value, so that the result looks like that. | ItemID | Date | ------------------------- | 1 | 06.01.10 | | 2 | 10.01.10 | Is there a easy way so get this data? Maybe using OVER? Thank you Torben

    Read the article

  • How do I translate a List<string> into a SqlParameter for a Sql In statement?

    - by KallDrexx
    I seem to be confused on how to perform an In statement with a SqlParameter. So far I have the following code: cmd.CommandText = "Select dscr from system_settings where setting in @settings"; cmd.Connection = conn; cmd.Parameters.Add(new SqlParameter("@settings", settingList)); reader = cmd.ExecuteReader(); settingsList is a List<string>. When cmd.ExecuteReader() is called, I get an ArgumentException due to not being able to map a List<string> to "a known provider type". How do I (safely) perform an In query with SqlCommands?

    Read the article

  • In SQL / MySQL, what is the difference between "On" and "Where" in a join statement?

    - by Jian Lin
    The following statements give the same result (one is using "on", and the other using "where"): mysql> select * from gifts INNER JOIN sentGifts on gifts.giftID = sentGifts.giftID; mysql> select * from gifts INNER JOIN sentGifts where gifts.giftID = sentGifts.giftID; I can only see in a case of a Left Outer Join finding the "unmatched" cases: (to find out the gifts that were never sent by anybody) mysql> select name from gifts LEFT OUTER JOIN sentgifts on gifts.giftID = sentgifts.giftID where sentgifts.giftID IS NULL; In this case, it is first using "on", and then "where". Does the "on" first do the matching, and then "where" does the "secondary" filtering? Or is there a more general rule of using "on" versus "where"? Thanks.

    Read the article

  • How does DATEDIFF calculate week differences in SQL Server 2005?

    - by eksortso
    I would like to calculate the difference in weeks between two dates, where two dates are considered part of the same week if their preceding Sunday is the same. Ideally, I'd like to do this using DATEDIFF, instead of learning an elaborate idiom to calculate the value. But I can't tell how it works when weeks are involved. The following query returns 1 and 2. This might make sense if your calendar week begins with a Sunday, i.e. if you run SET DATEFIRST 7 beforehand or if @@DATEFIRST is 7 by default. SET DATEFIRST 7; -- SET DATEFIRST 1; DECLARE @d1 DATETIME, @d2a DATETIME, @d2b DATETIME ; SELECT @d1 = '2010-04-05', -- Monday @d2a = '2010-04-16', -- Following Friday @d2b = '2010-04-18' -- the Sunday following ; SELECT DATEDIFF(week, @d1, @d2a) AS weekdiff_a -- returns 1 ,DATEDIFF(week, @d1, @d2b) AS weekdiff_b -- returns 2 ; So I expected different results if SET DATEFIRST 1 is executed instead of SET DATEFIRST 7. But the return values are the same, regardless! What is going on here? What should I do to get the correct week differences?

    Read the article

  • Is there a way to give a subquery an alias in Oracle 11g SQL?

    - by Matt Pascoe
    Is there a way to give a subquery in Oracle 11g an alias like: select * from (select client_ref_id, request from some_table where message_type = 1) abc, (select client_ref_id, response from some_table where message_type = 2) defg where abc.client_ref_id = def.client_ref_id; Otherwise is there a way to join the two subqueries based on the client_ref_id. I realize there is a self join, but on the database I am running on a self join can take up to 5 min to complete (there is some extra logic in the actual query I am running but I have determined the self join is what is causing the issue). The individual subqueries only take a few seconds to complete by them selves. The self join query looks something like: select st.request, st1.request from some_table st, some_table st1 where st.client_ref_id = st1.client_ref_id;

    Read the article

  • SQL - How to display the students with the same age?

    - by Cristian
    the code I wrote only tells me how many students have the same age. I want their names too... SELECT YEAR(CURRENT DATE-DATEOFBIRTH) AS AGE, COUNT(*) AS HOWMANY FROM STUDENTS GROUP BY YEAR(CURRENT DATE-DATEOFBIRTH); this returns something like this: AGE HOWMANY --- ------- 21 3 30 5 Thank you. TABLE STUDENTS COLUMNS: StudentID (primary key), Name(varchar), Firstname(varchar), Dateofbirth(varchar) I was thinking of maybe using the code above and somewhere add the function concat that will put the stundents' names on the same row as in

    Read the article

  • Multiple SQL Standard Instances on 4 Processor/32-core Server

    - by Theowood
    We have a large 4 processor/32-core server with 192GB of memory available in the data center and over twenty small SQL Standard databases to consolidate. They are a mix of SQL 2012 and 2008 R2 for 3rd-party apps. Is there any issue with simply installing two instances of SQL Standard on the server - one for 2012 and one for 2008 R2 ? Each instance will use up to 64GB out of the 192GB and 16 cores. If we did this with Enterprise, the licensing would be a fortune and the Enterprise features are not needed.

    Read the article

  • How do I write a Oracle SQl query for this tricky question...

    - by atrueguy
    Here is the table data with the column name as Ships. +--------------+ Ships | +--------------+ Duke of north | ---------------+ Prince of Wales| ---------------+ Baltic | ---------------+ In the Outcomes table, transform names of the ships containing more than one space, as follows: Replace all characters between the first and the last spaces (excluding these spaces) by symbols of an asterisk (*). The number of asterisks must be equal to number

    Read the article

  • How to change a primary key in SQL to auto_increment?

    - by Jian Lin
    I have a table in MySQL that has a primary key: mysql> desc gifts; +---------------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +---------------+-------------+------+-----+---------+-------+ | giftID | int(11) | NO | PRI | NULL | | | name | varchar(80) | YES | | NULL | | | filename | varchar(80) | YES | | NULL | | | effectiveTime | datetime | YES | | NULL | | +---------------+-------------+------+-----+---------+-------+ but I wanted to make it auto_increment. The following statement failed. How can it be modified so that it can work? thanks mysql> alter table gifts modify giftID int primary key auto_increment; ERROR 1068 (42000): Multiple primary key defined

    Read the article

  • How to correctly do SQL UPDATE with weighted subselect?

    - by luminarious
    I am probably trying to accomplish too much in a single query, but have I an sqlite database with badly formatted recipes. This returns a sorted list of recipes with relevance added: SELECT *, sum(relevance) FROM ( SELECT *,1 AS relevance FROM recipes WHERE ingredients LIKE '%milk%' UNION ALL SELECT *,1 AS relevance FROM recipes WHERE ingredients LIKE '%flour%' UNION ALL SELECT *,1 AS relevance FROM recipes WHERE ingredients LIKE '%sugar%' ) results GROUP BY recipeID ORDER BY sum(relevance) DESC; But I'm now stuck with a special case where I need to write the relevance value to a field on the same row as the recipe. I figured something along these lines: UPDATE recipes SET relevance=(SELECT sum(relevance) ...) But I have not been able to get this working yet. I will keep trying, but meanwhile please let me know how you would approach this?

    Read the article

  • How do I trace SQL Server Failure Audit events?

    - by Tim Perry
    I recently took over management of a Windows 2003 server. The application log is being filled up with messages like these: Event Type: Failure Audit Event Source: MSSQLSERVER Event Category: (4) Event ID: 18456 Date: 3/5/2010 Time: 4:00:30 PM User: N/A Computer: FAIROAKS1 Description: Login failed for user 'administrator'. [CLIENT: <local machine>] Data: 0000: 18 48 00 00 0e 00 00 00 .H...... 0008: 0a 00 00 00 46 00 41 00 ....F.A. 0010: 49 00 52 00 4f 00 41 00 I.R.O.A. 0018: 4b 00 53 00 31 00 00 00 K.S.1... 0020: 07 00 00 00 6d 00 61 00 ....m.a. 0028: 73 00 74 00 65 00 72 00 s.t.e.r. 0030: 00 00 .. For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp. I'd like to figure out what program is causing these. Is there a way to trace and find out which process is causing these errors?

    Read the article

  • Can I make an identity field span multiple tables in SQL Server?

    - by johnnycakes
    Can I have an "identity" (unique, non-repeating) column span multiple tables? For example, let's say I have two tables: Books and Authors. Authors AuthorID AuthorName Books BookID BookTitle The BookID column and the AuthorID column are identity columns. I want the identity part to span both columns. So, if there is an AuthorID with a value of 123, then there cannot be a BookID with a value of 123. And vice versa. I hope that makes sense. Is this possible? Thanks. Why do I want to do this? I am writing an APS.NET MVC app. I am creating a comment section. Authors can have comments. Books can have comments. I want to be able to pass an entity ID (a book ID or an author ID) to an action and have the action pull up all the corresponding comments. The action won't care if it's a book or an author or whatever. Sound reasonable?

    Read the article

  • Read and write .NET Objects in SQL Database without serialization.

    - by Mohit
    Hello, I have a small query. I need to create a Caching Service of my own that will write and read .NET Objects to and from the Database. Now, I have achieved that with the help of Binary Serialization. But the Problem is I need to deliberately marked my objects as [Serializable], which makes me think that what if someone will try to add an object which is not marked as [Serializable]. Thus, I need to find a way to read and write Objects to Database without Serialization. I have one thought too.. As we all know Session can store any object in it. Now, we can make sessions to be stored in the DB, outproc. What mechanism it uses to store these objects without serializing or deserializing. Any help will be highly appreciated. Thanks. M.B

    Read the article

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

< Previous Page | 473 474 475 476 477 478 479 480 481 482 483 484  | Next Page >