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  • Are database triggers evil?

    - by WW
    Are database triggers a bad idea? In my experience they are evil, because they can result in surprising side effects, and are difficult to debug (especially when one trigger fires another). Often developers do not even think of looking if there is a trigger. On the other hand, it seems like if you have logic that must occur evertime a new FOO is created in the database then the most foolproof place to put it is an insert trigger on the FOO table. The only time we're using triggers is for really simple things like setting the ModifiedDate.

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  • Sqlserver 2005 Replication issue

    - by Francesco
    Hi, I have a peer to peer Merge Replication from two Sqlserver 2005. The first Sqlserver is both the publisher and distribuitor. All works fine but if the VPN goes down for a couple of hours the replication goes down too and I need to manually restart the sqlserver agent. In the Sqlserver Agent properties I have set the two option about the agent failover but nothing. How I can set an automatic restart of sqlserver agent when the VPN goes down? Thanks

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  • How to designing a generic databse whos layout may change over time?

    - by mawg
    Here's a tricky one - how do I programatically create and interrogate a database who's contents I can't really foresee? I am implementing a generic input form system. The user can create PHP forms with a WYSIWYG layout and use them for any purpose he wishes. He can also query the input. So, we have three stages: a form is designed and generated. This is a one-off procedure, although the form can be edited later. This designs the database. someone or several people make use of the form - say for daily sales reports, stock keeping, payroll, etc. Their input to the forms is written to the database. others, maybe management, can query the database and generate reports. Since these forms are generic, I can't predict the database structure - other than to say that it will reflect HTML form fields and consist of a the data input from collection of edit boxes, memos, radio buttons and the like. Questions and remarks: A) how can I best structure the database, in terms of tables and columns? What about primary keys? My first thought was to use the control name to identify each column, then I realized that the user can edit the form and rename, so that maybe "name" becomes "employee" or "wages" becomes ":salary". I am leaning towards a unique number for each. B) how best to key the rows? I was thinking of a timestamp to allow me to query and a column for the row Id from A) C) I have to handle column rename/insert/delete. Foe deletion, I am unsure whether to delete the data from the database. Even if the user is not inputting it from the form any more he may wish to query what was previously entered. Or there may be some legal requirements to retain the data. Any gotchas in column rename/insert/delete? D) For the querying, I can have my PHP interrogate the database to get column names and generate a form with a list where each entry has a database column name, a checkbox to say if it should be used in the query and, based on column type, some selection criteria. That ought to be enough to build searches like "position = 'senior salesman' and salary 50k". E) I probably have to generate some fancy charts - graphs, histograms, pie charts, etc for query results of numerical data over time. I need to find some good FOSS PHP for this. F) What else have I forgotten? This all seems very tricky to me, but I am database n00b - maybe it is simple to you gurus?

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  • How to differentiate between two similar fields in Linq Join tables

    - by Azhar
    How to differentiate between two select new fields e.g. Description c.Description and lt.Description DataTable lDt = new DataTable(); try { lDt.Columns.Add(new DataColumn("AreaTypeID", typeof(Int32))); lDt.Columns.Add(new DataColumn("CategoryRef", typeof(Int32))); lDt.Columns.Add(new DataColumn("Description", typeof(String))); lDt.Columns.Add(new DataColumn("CatDescription", typeof(String))); EzEagleDBDataContext lDc = new EzEagleDBDataContext(); var lAreaType = (from lt in lDc.tbl_AreaTypes join c in lDc.tbl_AreaCategories on lt.CategoryRef equals c.CategoryID where lt.AreaTypeID== pTypeId select new { lt.AreaTypeID, lt.Description, lt.CategoryRef, c.Description }).ToArray(); for (int j = 0; j< lAreaType.Count; j++) { DataRow dr = lDt.NewRow(); dr["AreaTypeID"] = lAreaType[j].LandmarkTypeID; dr["CategoryRef"] = lAreaType[j].CategoryRef; dr["Description"] = lAreaType[j].Description; dr["CatDescription"] = lAreaType[j].; lDt.Rows.Add(dr); } } catch (Exception ex) { }

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  • Union on two tables with a where clause in the one

    - by Lostdrifter
    Currently I have 2 tables, both of the tables have the same structure and are going to be used in a web application. the two tables are production and temp. The temp table contains one additional column called [signed up]. Currently I generate a single list using two columns that are found in each table (recno and name). Using these two fields I'm able to support my web application search function. Now what I need to do is support limiting the amount of items that can be used in the search on the second table. the reason for this is become once a person is "signed up" a similar record is created in the production table and will have its own recno. doing: Select recno, name from production UNION ALL Select recno, name from temp ...will show me everyone. I have tried: Select recno, name from production UNION ALL Select recno, name from temp WHERE signup <> 'Y' But this returns nothing? Can anyone help?

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  • Using outer query result in a subquery in postgresql

    - by brad
    I have two tables points and contacts and I'm trying to get the average points.score per contact grouped on a monthly basis. Note that points and contacts aren't related, I just want the sum of points created in a month divided by the number of contacts that existed in that month. So, I need to sum points grouped by the created_at month, and I need to take the count of contacts FOR THAT MONTH ONLY. It's that last part that's tricking me up. I'm not sure how I can use a column from an outer query in the subquery. I tried something like this: SELECT SUM(score) AS points_sum, EXTRACT(month FROM created_at) AS month, date_trunc('MONTH', created_at) + INTERVAL '1 month' AS next_month, (SELECT COUNT(id) FROM contacts WHERE contacts.created_at <= next_month) as contact_count FROM points GROUP BY month, next_month ORDER BY month So, I'm extracting the actual month that my points are being summed, and at the same time, getting the beginning of the next_month so that I can say "Get me the count of contacts where their created at is < next_month" But it complains that column next_month doesn't exist This is understandable as the subquery knows nothing about the outer query. Qualifying with points.next_month doesn't work either. So can someone point me in the right direction of how to achieve this? Tables: Points score | created_at 10 | "2011-11-15 21:44:00.363423" 11 | "2011-10-15 21:44:00.69667" 12 | "2011-09-15 21:44:00.773289" 13 | "2011-08-15 21:44:00.848838" 14 | "2011-07-15 21:44:00.924152" Contacts id | created_at 6 | "2011-07-15 21:43:17.534777" 5 | "2011-08-15 21:43:17.520828" 4 | "2011-09-15 21:43:17.506452" 3 | "2011-10-15 21:43:17.491848" 1 | "2011-11-15 21:42:54.759225" sum, month and next_month (without the subselect) sum | month | next_month 14 | 7 | "2011-08-01 00:00:00" 13 | 8 | "2011-09-01 00:00:00" 12 | 9 | "2011-10-01 00:00:00" 11 | 10 | "2011-11-01 00:00:00" 10 | 11 | "2011-12-01 00:00:00"

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  • Check if access table exists

    - by HasanGursoy
    I want to log web site visits' IP, datetime, client and refferer data to access database but I'm planning to log every days log data in separate tables in example logs for 06.06.2010 will be logged in 2010_06_06 named table. When date is changed I'll create a table named 2010_06_07. But the problem is if this table is already created. Any suggestions how to check if table exists in Access?

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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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  • Any way to speed up this hierarchical query?

    - by RenderIn
    I've got a serious performance problem with a hierarchical query that I can't seem to fix. I am modeling several organization charts in my database, each representing a virtual organization within our company. For example, we have several temporary committees that are created from time to time and there may be a Committee Organizer role at the top of this virtual hierarchy, with several people assigned to the Committee Member role beneath the organizer. Some of our virtual organizations have many levels and several branches at each level. I have a single table in which I represent all the role assignments. i.e. a ROLE_ID column and a PARENT_ROLE_ID column which is a foreign key to the ROLE_ID column. For each assignment we also store as a column the location in the company where this person has the assignment. For example, the Committee Organizer would have a company-level/ CEO assignment, while the committee members would have department-level assignments such as ACCOUNTING, MARKETING, etc. So to model the organizer/member relationship for two individuals we would have: ROLE_ID = 4 PARENT_ROLE_ID = NULL EMPLOYEE_NUMBER = 213423 COMPANY_LOCATION = CEO ROLE_ID = 5 PARENT_ROLE_ID = 4 EMPLOYEE_NUMBER = 838221 COMPANY_LOCATION = ACCOUNTING Here's where things get tricky. I have an application that every person in the organization can log in to. When they log in they should be able to view all the virtual organizations in our company. e.g. the committee members should be able to see the committee organizer and vice-versa. However, only the committee organizer should be able to edit the committee members. The difficulty is in determining whether an individual (who can have multiple role assignments) has edit access for each other assignment. While this seems simple in the example, consider a virtual organization in which we have President at the top, 5 departments directly beneath him, 2 subdepartments below each department. We only want people in the Accounting department to be able to edit individuals in the subdepartments belonging to the Accounting department. They should not have edit access to anybody in the Marketing department or its subdepartments. To determine edit access when a user views a virtual organization in our company I run a query that executes two inline views: A) Hierarchically query for all assignments in this virtual organization and using SYS_CONNECT_BY_PATH to store the entire path to each user/role/company_location and B) Hierarchically retrieve all the assignments the individual logged in has and using the SYS_CONNECT_BY_PATH to store the entire path to each of these assignments. The result of the query is all the records from A) plus a boolean determined by joining with B) which flags whether the logged in user has edit access for each record. Indexes don't seem to be helping... it simply appears that there is too much processing going on to separate all the records and then determine edit access. One issue is that I can't store the SYS_CONNECT_BY_PATH and index it... determining whether an individual record has edit access consists of comparing if: test_record_sys_path LIKE individual_record_sys_path || '%' Is a materialized view the answer?

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  • Creating a Rails query from a hash of user input

    - by Jamie
    I'm attempting to create a fairly complex search engine for a project using a variable number of search criteria. The user input is sorted into an array of hashes. The hashes contain the following information: { :column => "", :value => "", :operator => "", # Such as: =, !=, <, >, etc. :and_or => "", # Two possible values: "and" and "or" } How can I loop through this array and use the information in these hashes to make an ActiveRecord WHERE query?

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  • Tables with no Primary Key

    - by Matt Hamilton
    I have several tables whose only unique data is a uniqueidentifier (a Guid) column. Because guids are non-sequential (and they're client-side generated so I can't use newsequentialid()), I have made a non-primary, non-clustered index on this ID field rather than giving the tables a clustered primary key. I'm wondering what the performance implications are for this approach. I've seen some people suggest that tables should have an auto-incrementing ("identity") int as a clustered primary key even if it doesn't have any meaning, as it means that the database engine itself can use that value to quickly look up a row instead of having to use a bookmark. My database is merge-replicated across a bunch of servers, so I've shied away from identity int columns as they're a bit hairy to get right in replication. What are your thoughts? Should tables have primary keys? Or is it ok to not have any clustered indexes if there are no sensible columns to index that way?

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  • Split function in where clause

    - by abhishek-khandelwal
    hello friends I am using following query in linq In product table following type of data are stored abc-def bcd=fgh abc-xyz var query=from prod in db.Product join cat in db.category on prod.categoryId=cat.categoryID where prod.productName.split('-')[0]=="abc" but in that query it product annoumous problem Please give some suggestion to split in where caluse

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  • How to sort a gridview once a radio button is selected

    - by metashockwave
    I'm trying to sort records in the gridview right after a radio button is selected. My approach is with the dataview, but because the dataset variable doesn't survive a round trip to the server, I don't know how to make this happen. please help! Public Sub GetCustomers() db.RunProcedure("usp_customers_get_all") db.doSort(radList.SelectedValue) gvCustomers.DataSource = db.MyView End Sub Protected Sub radList_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles radList.SelectedIndexChanged If radList.SelectedValue = 0 Then db.doSort(0) gvCustomers.DataSource = db.MyView End If If radList.SelectedValue = 1 Then db.doSort(1) gvCustomers.DataSource = db.MyView End If End Sub Public Sub doSort(ByVal strIn As Integer) If strIn = 0 Then MyView.Sort = "lastname, firstname" Else MyView.Sort = "username" End If End Sub Public Sub RunProcedure(ByVal strName As String) Dim objConnection As New SqlConnection(mstrConnection) Dim mdbDataAdapter As New SqlDataAdapter(strName, objConnection) Try mdbDataAdapter.SelectCommand.CommandType = CommandType.StoredProcedure Me.mDataset.Clear() mdbDataAdapter.Fill(mDataset, "tblCustomers") MyView.Table = mDataset.Tables("tblCustomers") Catch ex As Exception Throw New Exception("stored procedure is " & strName.ToString & " error is " & ex.Message) End Try End Sub

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  • What are the types and inner workings of a query optimizer?

    - by Frank Developer
    As I understand it, most query optimizers are cost-based. Some can be influenced by hints like FIRST_ROWS(). Others are tailored for OLAP. Is it possible to know more detailed logic about how Informix IDS and SE's optimizers decide what's the best route for processing a query, other than SET EXPLAIN? Is there any documentation which illustrates the ranking of SELECT statements? I would imagine that "SELECT col FROM table WHERE ROWID = n" ranks 1st. What are the rest of them?.. If I'm not mistaking, Informix's ROWID is a SERIAL(INT) which allows for a max. of 2GB nrows, or maybe it uses INT9 for TB's nrows?.. However, I think Oracle uses HEX values for ROWID. Too bad ROWID can't be oftenly used, since a rows ROWID can change. So maybe ROWID is used by the optimizer as a counter? Perhaps, it could be used for implementing the query progress idea I mentioned in my "Begin viewing query results before query completes" question? For some reason, I feel it wouldn't be that difficult to report a query's progress while being processed, perhaps at the expense of some slight overhead, but it would be nice to know ahead of time: A "Google-like" estimate of how many rows meet a query's criteria, display it's progress every 100, 200, 500 or 1,000 rows, give users the ability to cancel it at anytime and start displaying the qualifying rows as they are being put into the current list, while it continues searching?.. This is just one example, perhaps we could think other neat/useful features, the ingridients are more or less there. Perhaps we could fine-tune each query with more granularity than currently available? OLTP queries tend to be mostly static and pre-defined. The "what-if's" are more OLAP, so let's try to add more control and intelligence to it? So, therefore, being able to more precisely control, not "hint-influence" a query is what's needed and therefore it would be necessary to know how the optimizers logic is programmed. We can then have Dynamic SELECT and other statements for specific situations! Maybe even tell IDS to read blocks of indexes nodes at-a-time instead of one-by-one, etc. etc.

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  • select rows with column that is not null?

    - by fayer
    by default i have one column in mysql table to be NULL. i want to select some rows but only if the field value in that column is not NULL. what is the correct way of typing it? $query = "SELECT * FROM names WHERE id = '$id' AND name != NULL"; is this correct?

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  • DELETE from two tables with one OUTPUT clause?

    - by lance
    This deletes the document from the Document table and outputs information about the deleted document into the FinishedDocument table. DELETE FROM Document OUTPUT Deleted.DocumentId , Deleted.DocumentDescription INTO FinishedDocument WHERE DocumentId = @DocumentId I need to delete the document not just from the Document table, but also from the DocumentBackup table. Meanwhile, I need to maintain insertion into FinishedDocument. Is all of this possible with only one statement? If not, is a second DELETE (against DocumentBackup), with all of it wrapped in a transaction, the way to go?

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  • Concatenating rows from different tables into one field

    - by Markus
    Hi! In a project using a MSSQL 2005 Database we are required to log all data manipulating actions in a logging table. One field in that table is supposed to contain the row before it was changed. We have a lot of tables so I was trying to write a stored procedure that would gather up all the fields in one row of a table that was given to it, concatenate them somehow and then write a new log entry with that information. I already tried using FOR XML PATH and it worked, but the client doesn't like the XML notation, they want a csv field. Here's what I had with FOR XML PATH: DECLARE @foo varchar(max); SET @foo = (SELECT * FROM table WHERE id = 5775 FOR XML PATH('')); The values for "table", "id" and the actual id (here: 5775) would later be passed in via the call to the stored procedure. Is there any way to do this without getting XML notation and without knowing in advance which fields are going to be returned by the SELECT statement?

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  • Chain LINQ IQueryable, and end with Stored Procedure

    - by Alex
    I'm chaining search criteria in my application through IQueryable extension methods, e.g.: public static IQueryable<Fish> AtAge (this IQueryable<Fish> fish, Int32 age) { return fish.Where(f => f.Age == age); } However, I also have a full text search stored procedure: CREATE PROCEDURE [dbo].[Fishes_FullTextSearch] @searchtext nvarchar(4000), @limitcount int AS SELECT Fishes.* FROM Fishes INNER JOIN CONTAINSTABLE(Fishes, *, @searchtext, @limitcount) AS KEY_TBL ON Fishes.Id = KEY_TBL.[KEY] ORDER BY KEY_TBL.[Rank] The stored procedure obviously doesn't return IQueryable, however, is it possible to somehow limit the result set for the stored procedure using IQueryable's? I'm envisioning something like .AtAge(5).AboveWeight(100).Fishes_FulltextSearch("abc"). In this case, the fulltext search should execute on a smaller subset of my Fishes table (narrowed by Age and Weight). Is something like this possible? Sample code?

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  • Re-indexing table; update with from

    - by David Thorisson
    The query says it all, I can't find out the right syntax without without using a for..next UPDATE Webtree SET Webtree.Sorting=w2.Sorting FROM ( SELECT BranchID, CASE WHEN @Index>=ROW_NUMBER() OVER(ORDER BY Sorting ASC) THEN ROW_NUMBER() OVER(ORDER BY Sorting ASC) ELSE ROW_NUMBER() OVER(ORDER BY Sorting ASC)+1 END AS Sorting FROM Webtree w2 WHERE w2.ParentID=@ParentID ) WHERE Webtree.BranchID=w2.BranchID

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