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  • MySQL - are FK's useful / viable in a web app?

    - by yoda
    Hi all, I've encountered this discussion related to FK's and web applications. Basically some people say that FK's in web applications doesn't represent a real improvement and can even make the application slower in some cases. What do you guys think, what's your experience? -- A quote from Heikki Tuuri, creator of InnoDB engine, founder and CEO of Innobase: InnoDB checks foreign keys as soon as a row is updated, no batching is performed or checks delayed till transaction commit Foreign keys are often serious performance overhead, but help maintain data consistency Foreign Keys increase amount of row level locking done and can make it spread to a lot of tables besides the ones directly updated

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  • How do you compare dates in a LINQ query?

    - by Gina
    I am tring to compare a date from a asp calendar control to a date in the table.... here's what i have... it doesn't like the == ? var query = from details in db.TD_TravelCalendar_Details where details.StartDate == calStartDate.SelectedDate && details.EndDate == calEndDate.SelectedDate select details;

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  • What's the best way to migrate a Django DB from SQLite to MySQL?

    - by Inshim
    I need to migrate my db from sqlite to mysql, and the various tools/scripts out there are too many for me to easily spot the safest and most elegant solution. This seemed to me nice http://djangosnippets.org/snippets/14/ but appears to be 3 years since getting an update which is worrying.. Can you recommend a solution that is known to be reliable with Django 1.1.1 ?

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  • How to check value of stored procedure output parameter

    - by Anna T
    I have a stored procedure that: A. inserts some rows into a "table variable" based on some joins B. selects all values from column x from that table into a string with comma separated values C. selects all from the "table variable" If I execute the procedure like this: EXEC CatalogGetFilmDetails2 2,111111; a table is returned as instructed per step C above. How can I execute it so that also the output parameter value is displayed? (see point B above). I need to check if it's calculated properly. And since the second parameter is of output type, meaning it's calculated inside the procedure, why is it mandatory to specify a value for it when executing the procedure? I normally use a random value for it, it anyway doesn't matter/impact the result. On the other hand if I try to execute it without the output parameter, it returns an error) Thank you very much! This is how the procedure starts: CREATE PROCEDURE CatalogGetFilmDetails2 (@FilmID int, @CommaSepString VARCHAR(50) OUTPUT) AS And this is how @CommaSepString is calculated: SELECT @CommaSepString = STUFF((SELECT ', ' + Categ FROM @Filme1 FOR XML PATH('')), 1,1,'')

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  • How do these user/userParam references relate to the Customer and Account lookups?

    - by marmalade
    In the following code example how do the user/userParam references relate to the Customer and Account lookups and what is the relationship between Customer and Account? // PersistenceManager pm = ...; Transaction tx = pm.currentTransaction(); User user = userService.currentUser(); List<Account> accounts = new ArrayList<Account>(); try { tx.begin(); Query query = pm.newQuery("select from Customer " + "where user == userParam " + "parameters User userParam"); List<Customer> customers = (List<Customer>) query.execute(user); query = pm.newQuery("select from Account " + "where parent-pk == keyParam " + "parameters Key keyParam"); for (Customer customer : customers) { accounts.addAll((List<Account>) query.execute(customer.key)); } } finally { if (tx.isActive()) { tx.rollback(); } }

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  • Entity Framework Duplicate type name within an assembly (6.1.0)

    - by CodeMilian
    I am not sure what is going on but I keep getting the following exception when doing a query. "Duplicate type name within an assembly." I have not been able to find a solution on the web. I had resolved the issue by removing entity framework from all the projects in the solutions and re-installing using nugget. Then all of the sudden the exception is back. I have verified my table schema over and over and find nothing wrong with. This is the query causing the exception. var BaseQuery = from Users in db.Users join UserInstalls in db.UserTenantInstalls on Users.ID equals UserInstalls.UserID join Installs in db.TenantInstalls on UserInstalls.TenantInstallID equals Installs.ID where Users.Username == Username && Users.Password == Password && Installs.Name == Install select Users; var Query = BaseQuery.Include("UserTenantInstalls.TenantInstall"); return Query.FirstOrDefault(); As I mentioned previously the same query was working before. The data has not changed and the code has not changed.

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  • How to achieve high availability?

    - by tanyehzheng
    My boss wants to have a system that takes into concern of continent wide catastrophic event. He wants to have two servers in US and two servers in Asia (1 login server and 1 worker server in each continent). In the event that earthquake breaks the connection between the two continents, both should work alone. When the connection is revived, they should sync each other back to normal. External cloud system not allowed as he has no confidence. The system should take into account of scalability which means addition of new servers should be easy to configure. The servers should be load balanced. The connection between the servers should be very secure(encrypted and send through SSL although SSL takes care of encryption). The system should let one and only one user log in with one account. (beware of latency between continent and two users sharing account may reach both login server at the same time) Please help. I'm already at the end of my wit. Thank you in advance.

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  • Date format error in vb.net ?

    - by ahmed
    I get this error when I run the application Incorrect syntax near 12, on debugging I found that this error is caused due to the # along with the date. Dim backdate as datetime backdate = DateTime.Now.AddDays(-1) on binding the data to the grid to filter the backdate records this error is caused Incorrect syntax near 12. myqry = " select SRNO,SUBJECT,ID where datesend =" backdate Now i am trying to extract only the date or shall I divide the date into day , month and year with DATEPART and take into a variable or convert the date or what should i do , Please help ???

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  • Unit testing a SQL code generator

    - by Tom H.
    The team I'm on is currently writing code in TSQL to generate TSQL code that will be saved as scripts and later run. We're having a little difficulty in separating our unit tests between testing the code generator parts and testing the actual code that they generate. I've read through another similar question, but I was hoping to get some specific examples of what kind of unit test cases we might have. As an example, let's say that I have a bit of code that simply generates a DROP statement for a view, given the view schema and name. Do I just test that the generated code matches some expected outcome using string comparisons and then in a later integration or system test make sure that the drop actually drops the view if it exists, does nothing if the view doesn't exist, or raises an error if the view is one that we are marking as not allowing a drop? Thanks for any advice!

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  • MYSQL join - reference external field from nested select?

    - by PHP thinker
    Is it allowed to reference external field from nested select? E.g. SELECT FROM ext1 LEFT JOIN (SELECT * FROM int2 WHERE int2.id = ext1.some_id ) as x ON 1=1 in this case, this is referencing ext1.some_id in nested select. I am getting errors in this case that field ext1.some_id is unknow. Is it possible? Is there some other way?

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  • counting rows that date hasn't yet passed

    - by AdRock
    I am trying to count the number of rows whose date has not yet passed so i can get only the current records I get an error sayng MySQL error #111 Invalid use of group function SELECT COUNT(festivalid) FROM festivals WHERE min(datefrom) > now()

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  • Why does this query only select a single row?

    - by Joe
    SELECT * FROM tbl_houses WHERE (SELECT HousesList FROM tbl_lists WHERE tbl_lists.ID = '123') LIKE CONCAT('% ', tbl_houses.ID, '#') It only selects the row from tbl_houses of the last occuring tbl_houses.ID inside tbl_lists.HousesList I need it to select all the rows where any ID from tbl_houses exists within tbl_lists.HousesList

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  • Access DoCmd.OpenForm Not Working

    - by user961743
    Looking for a second set of eyes to figure out my problem with an Access form filter. I created a search form, when filled in, appends search criteria to a string variable (strQuery) that is put in place to the [WhereCondition] for opening a form. However, when the script is ran, nothing comes up except for a filtered form with no records. Here is the line that opens the form: DoCmd.OpenForm "ADD_NEW_NCMR", , , strQuery Before the line is ran, strQuery equals: 1=1 AND [NCMR].[NCMR_NUM] = '12-129' The form name, and table.column combination are all correct. In fact, using the DCount function returns the result of 1, which is correct for this query, and returns the correct number for other queries as well. This makes me think that there is nothing wrong with the where condition. DCount("[NCMR_NUM]", "NCMR", strQuery)

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  • PDO update query with conditional?

    - by dmontain
    I have a PDO mysql that updates 3 fields. $update = $mypdo->prepare("UPDATE tablename SET field1=:field1, field2=:field2, field3=:field3 WHERE key=:key"); But I want field3 to be updated only when $update3 = true; (meaning that the update of field3 is controlled by a conditional statement) Is this possible to accomplish with a single query? I could do it with 2 queries where I update field1 and field2 then check the boolean and update field3 if needed in a separate query. //run this query to update only fields 1 and 2 $update_part1 = $mypdo->prepare("UPDATE tablename SET field1=:field1, field2=:field2 WHERE key=:key"); //if field3 should be update, run a separate query to update it separately if ($update3){ $update_part2 = $mypdo->prepare("UPDATE tablename SET field3=:field3 WHERE key=:key"); } But hopefully there is a way to accomplish this in 1 query?

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  • is it possible to lock oracle 10g database table with ADO.NET?

    - by matti
    I have a table that contains a maximum value that needs to be get and set by multiple programs. How can I lock the table for a while when old value is got and new is updated in C#? In other words: string sql = "lock table MaxValueTable in exclusive mode"; using (DbCommand cmd = cnctn.CreateCommand()) { cmd.CommandText = sql; // execute command somehow!! } maxValue = GetMaxValue(); SetMaxValue(maxValue + X); sql = "lock table MaxValueTable in share mode"; using (DbCommand cmd = cnctn.CreateCommand()) { cmd.CommandText = sql; // execute command somehow!! }

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  • How do you determine an acceptable response time for DB requests?

    - by qiq
    According to this discussion of Google App Engine on Hacker News, A DB (read) request takes over 100ms on the datastore. That's insane and unusable for about 90% of applications. How do you determine what is an acceptable response time for a DB read request? I have been using App Engine without noticing any issues with DB responsiveness. But, on the other hand, I'm not sure I would even know what to look for in that regard :)

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  • Extending LINQ classes to my own partial classes in different namespaces?

    - by sah302
    I have a .dbml file which of course contains the auto-generated classes based on my tables. I would however, like to extend them to my own classes. Typically I design such that each of my tables get their own namespace in their own folder containing all of their associated dao and service classes. So if I am dealing with a page that only has to do with 'customers' for instance, I can only include the customerNS. But when using LINQ I seem to be unable to do this. I have tried removing a default namespace from the project, I have tried putting the .dbml file into it's own folder with a custom namespace and then adding a 'using' statement, but no nothing works. I also saw the Entity Namespace, Context Namespace, and Custom Tool Namespace properties associated with the .dbml file and tried setting all these to names x and trying 'using x' in my other class to allow me to extend partial classes, but it just doesn't work. Is this possible or do I have to keep all extended partial classes in the same namespace as the .dbml file?

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  • Acceessing some aggregate functions in a linq datasource in a GridView

    - by Stephen Pellicer
    I am working on a traditional WebForms project. In the project I am trying out some Linq datasources with plans to eventually migrate to an MVC architecture. I am still very new to Linq. I have a GridView using a Linq datasource. The entities I am showing has a to many relationship and I would like to get the maximum value of a column in the many side of the relationship. I can show properties of the base entity in the gridview: <asp:TemplateField HeaderText="Number" SortExpression="tJobBase.tJob.JobNumber"> <ItemTemplate> <asp:Label ID="Label1" runat="server" Text='<%# Bind("tJobBase.tJob.JobNumber") %>'> </asp:Label> </ItemTemplate> </asp:TemplateField> I can also show the count of the many related property: <asp:TemplateField HeaderText="Number" SortExpression="tJobBase.tJob.tHourlies.Count"> <ItemTemplate> <asp:Label ID="Label1" runat="server" Text='<%# Bind("tJobBase.tJob.tHourlies.Count") %>'> </asp:Label> </ItemTemplate> </asp:TemplateField> Is there a way to get the max value of a column called WeekEnding in the tHourlies collection to show in the GridView?

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  • SYSDATE - 1 error on pl/sql function

    - by ayo
    Hi curtisk/all, I have an issue: when i issue this function below ti gives me the following error: select 'EXECUTE DBMS_LOGMNR.ADD_LOGFILE(LOGFILENAME =>'''||name||'''||,OPTIONS=>DBMS_LOGMNR.NEW);' from v\$archived_log where name is not null; select 'EXECUTE DBMS_LOGMNR.ADD_LOGFILE(LOGFILENAME =>'''||name||'''||,OPTIONS=>DBMS_LOGMNR.ADDFILE);' from v\$archived_log where name is not null; EXECUTE DBMS_LOGMNR.START_LOGMNR( STARTTIME => SYSDATE - 1, ENDTIME => SYSDATE, OPTIONS => DBMS_LOGMNR.DICT_FROM_ONLINE_CATALOG + DBMS_LOGMNR.CONTINUOUS_MINE + DBMS_LOGMNR.COMMITTED_DATA_ONLY + DBMS_LOGMNR.PRINT_PRETTY_SQL); Error: * ERROR at line 1: ORA-01291: missing logfile ORA-06512: at "SYS.DBMS_LOGMNR", line 58 ORA-06512: at line 1 But i have added all the archived logs for several days before and my sysdate is at today. Kindly help out on this issue. thanks. Reagrds Ayo

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  • TSQL: grouping customer orders by week

    - by fishhead
    I have a table with a collection of orders. The fields are: customerName (text) DateOfOrder (datetime). I would like to show totals of orders per week per customer. I would like to have it arranged for the Friday of each week so that it looks like this: all dates follow mm/dd/yyyy "bobs pizza", 3/5/2010, 10 "the phone co",3/5/2010,5 "bobs pizza", 3/12/2010, 3 "the phone co",3/12/2010,11 Could somebody please show me how to do this? Thanks

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