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  • Find all those columns which have only null values, in a MySQL table

    - by Robin v. G.
    The situation is as follows: I have a substantial number of tables, with each a substantial number of columns. I need to deal with this old and to-be-deprecated database for a new system, and I'm looking for a way to eliminate all columns that have - apparently - never been in use. I wanna do this by filtering out all columns that have a value on any given row, leaving me with a set of columns where the value is NULL in all rows. Of course I could manually sort every column descending, but that'd take too long as I'm dealing with loads of tables and columns. I estimate it to be 400 tables with up to 50 (!) columns per table. Is there any way I can get this information from the information_schema? EDIT: Here's an example: column_a column_b column_c column_d NULL NULL NULL 1 NULL 1 NULL 1 NULL 1 NULL NULL NULL NULL NULL NULL The output should be 'column_a' and 'column_c', for being the only columns without any filled in values.

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  • Relating text fields to check boxes in Java

    - by Finzz
    This program requires the user to login and request a database to access. The program then gets a connection object, searches through the database storing the column names into a vector for later use. The problem comes with implementing text fields to allow the user to search for specific values within the database. I can get the check boxes and text fields to appear using a gridlayout and add them to a panel. How do I relate the text fields to their appropriate check box? I've tried adding them to a vector, but then they can't also be added to the panel as well. I've searched for a way to name the text fields as the loop cycles through the column names, but it seems impossible to do without having them declared ahead of time. This can't be done either, as it's impossible to determine the attributes that the user will request. I just need to be able to know the names of the text fields so I can test to see if the user entered information and perform the necessary logic. Let me know if you have to see the rest of the code to give an answer, but hopefully you get the general idea of what I'm trying to accomplish. Picture of UI: try { ResultSet r2 = con.getMetaData().getColumns("", "", rb.getText(), ""); colNames1 = new Vector<String>(); columns1 = new Vector<JCheckBox>(); while (r2.next()) { colNames1.add(r2.getString(4)); JCheckBox cb = new JCheckBox(r2.getString(4)); JTextField tf = new JTextField(10); columns1.add(cb); p3.add(cb); p3.add(tf); } }

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  • connecting to mysql from excel: ODBC driver does not support the requested properties.

    - by every_answer_gets_a_point
    i am trying to add data to mysql from excel. i am getting the above error on this line: rs.Open strSQL, oConn, adOpenDynamic, adLockOptimistic here is my code: Dim oConn As ADODB.Connection Private Sub ConnectDB() Set oConn = New ADODB.Connection oConn.Open "DRIVER={MySQL ODBC 5.1 Driver};" & _ "SERVER=localhost;" & _ "DATABASE=employees;" & _ "USER=root;" & _ "PASSWORD=some_pass;" & _ "Option=3" End Sub Function esc(txt As String) esc = Trim(Replace(txt, "'", "\'")) End Function Private Sub InsertData() Dim rs As ADODB.Recordset Set rs = New ADODB.Recordset ConnectDB With wsBooks For rowCursor = 2 To 11 strSQL = "INSERT INTO tutorial (author, title, price) " & _ "VALUES ('" & esc(.Cells(rowCursor, 1)) & "', " & _ "'" & esc(.Cells(rowCursor, 2)) & "', " & _ esc(.Cells(rowCursor, 3)) & ")" rs.Open strSQL, oConn, adOpenDynamic, adLockOptimistic Next End With End Sub whats wrong with rs.Open strSQL, oConn, adOpenDynamic, adLockOptimistic ? why am i getting the odbc error?

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  • Caching stored procedure results in Linq'u

    - by itdebeloper
    In our web application we have a lots of stored procedures look like this one: getSomeData(/* 7 diffrent params */) This stored procedure don't make any updates. We are using Linq'u. I know that the date are changing no often than once per day so the results for the same sets of parameters values will be the same. Does Linqu have cache simple solution? I know how to 'manually' write cache mechanism in .net, but I supposed that in Linqu this problem was solved. I'm a lazy guy :) so I'm looking for something realy simple like: Linqu_global_store_procedure_configuration.CacheDuration="600" Linqu_global_store_procedure_configuration.CacheVaryByParam="*" I'm using .net 3.5 but its not any problem to move for 4.0.

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  • postgres subquery w/ derived column

    - by Wells
    The following query won't work, but it should be clear what I'm trying to do: split the value of 't' on space and use the last element in that array in the subquery (as it will match tl). Any ideas how to do this? Thanks! SELECT t, y, "type", regexp_split_to_array(t, ' ') as t_array, sum(dr), ( select uz from f.tfa where tl = t_array[-1] ) as uz, sc FROM padres.yd_fld WHERE y = 2010 AND pos <> 0 GROUP BY t, y, "type", sc;

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  • SQL time issue - need it 6 hours forward!

    - by Luke
    My server is currently based on us eastern time, and as I am in the UK, i need to move this forward 6 hours. When using now() in mysql, i am getting the wrong time, is there anything i can add to now() to bring it forward 6 hours? Thanks

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  • Collection was modified; enumeration operation may not execute

    - by Rita
    I have the below code. I am trying to remove the record and it is throwing Exception when it is removing the Record. "Collection was modified; enumeration operation may not execute." Any ideas on how to get rid of the message. Appreciate your time. //validClaimControlNo has valid ClaimControl Numbers. List<string> validClaimControlNo = new List<string>(); int count = 0; foreach (List<Field> f in records) { foreach (Field fe in f) { if (i == 0) if (!(validClaimControlNo.Contains(fe.Value))) { //if this claim is not in the Valid list, Remove that Record records.RemoveAt(count); } i++; } i = 0; count++; }

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  • Multiple user database design

    - by dieguitoweb
    I have to develop a basic social network for an academic purpose; but I need some tips for the users management.. The users are subdivided into 3 groups with different privilege: admins,analysts and standards users. For every user should be stored into the database the following information: name,lastname,e-mail,age,password. I'm not quite sure how I should design the database between theese two solutions: 1)one table called 'users' with the 'role' attribute that explain what a user can do and what can't do, and the permissions are managed via php 2)every application user is a database user created with the query 'CREATE ROLE' (It's a postgres database) and he has permissions on some tables granted with the 'GRANT' statement You should take into account that the project is for a database exam.. thanks

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  • best database design for city zip & state tables

    - by ryan a
    My application will need to reference addresses. Street info will be stored with my main objects but the rest needs to be stored seperately to reduce redundancy. How should I store/retrieve ZIPs, cities and states? Here are some of my ideas. single table solution (cant do relationships) [locations] locationID locationParent (FK for locationID - 0 for state entries) locationName (city, state) locationZIP two tables (with relationships, FK constraints, ref integrity) [state] stateID stateName [city] cityID stateID (FK for state.stateID) cityName zipCode three tables [state] stateID stateName [city] cityID stateID (FK for state.stateID) cityName [zip] zipID cityID (FK for city.cityID) zipName Then I read into ZIP codes amd how they are assigned. They aren't specifically related to cities. Some cities have more than one ZIP (ok will still work) but some ZIPs are in more than one city (oh snap) and some other ZIPs (very few) are in more than one state! Also some ZIPs are not even in the same state as the address they belong to at all. Seems ZIPs are made for carrier route identification and some remote places are best served by post offices in neighboring cities or states. Does anybody know of a good (not perfect) solution that takes this into consideration to minimize discrepencies as the database grows?

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  • Storing Result set into an array

    - by OVERTONE
    i know this should be simpel and im probably staring straight at the problem but once again im stuck and need the help of the code gurus. im trying too take one row from a column in jdbc, and put them in an array. i do this as follows: public void fillContactList() { createConnection(); try { Statement stmt = conn.createStatement(); ResultSet namesList = stmt.executeQuery("SELECT name FROM Users"); try { while (namesList.next()) { contactListNames[1] = namesList.getString(1); System.out.println("" + contactListNames[1]); } } catch(SQLException q) { } conn.commit(); stmt.close(); conn.close(); } catch(SQLException e) { } creatConnection is an already defined method that does what it obviously does. i creat my result set while theres another one, i store the string of that column into an array. then print it out for good measure. too make sure its there. the problem is that its storing the entire column into contactListNames[1] i wanted to make it store column1 row 1 into [1] then column 1 row 2 into [2] i know i could do this with a loop. but i dont know too take only one row at a time from a single column. any ideas? p.s ive read the api, i jsut cant see anything that fits.

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  • How can I improve the below query?

    - by Newbie
    I have the following input. INPUT: TableA ID Sentences --- ---------- 1 I am a student 2 Have a nice time guys! What I need to do is to extract the words from the sentence(s) and insert each individual word in another table OUTPUT: SentenceID WordOccurance Word ---------- ------------ ----- 1 1 I 1 2 am 1 3 a 1 4 student 2 1 Have 2 2 a 2 3 nice 2 4 time 2 5 guys! I was able to get the answer by using the below query ;With numCTE As ( Select rn = 1 Union all Select rn+1 from numCTE where rn<1000) select SentenceID=id, WordOccurance=row_number()over(partition by TableA.ID order by rn), Word = substring(' '+sentences+' ', rn+1, charindex(' ',' '+sentences+' ', rn+1)-rn-1) from TableA join numCTE on rn <= len(' '+sentences+' ') where substring(' '+sentences+' ', rn,1) = ' ' order by id, rn How can I improve this query of mine.? Basically I am looking for a better solution than the one presented Thanks

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  • How do I use on delete cascade in mysql?

    - by Marius
    I have a database of components. Each component is of a specific type. That means there is a many-to-one relationship between a component and a type. When I delete a type, I would like to delete all the components which has a foreign key of that type. But if I'm not mistaken, cascade delete will delete the type when the component is deleted. Is there any way to do what I described?

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  • Oracle select query

    - by Jasim
    I have a table like this C1 C2 C3 Code 1 2 3 33 1 2 3 34 2 4 1 14 1 2 3 14 i want to select only those record whose code is appearing only in single row. ie, in this case rows with code 33 and 34.. as they appear only once in this table. How can i write a query for that

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  • Rails 3 fields_for agressive loading?

    - by Seth
    Hi all, I'm trying to optimize (limit) queries in a view. I am using the fields_for function. I need to reference various properties of the object, such as username for display purposes. However, this is a rel table, so I need to join with my users table. The result is N sub-queries, 1 for each field in fields_for. It's difficult to explain, but I think you'll understand what I'm asking if I paste my code: <%= form_for @election do |f| %> <%= f.fields_for :voters do |voter| %> <%= voter.hidden_field :id %> <%= voter.object.user.preferred_name %> <% end %> <% end %> I have like 10,000 users, and many times each election will include all 10,000 users. That's 10,000 subqueries every time this view is loaded. I want fields_for to JOIN on users. Is this possible? I'd like to do something like: ... <%= f.fields_for :voters, :joins => :users do |voter| %> ... <% end %> ... But that, of course, doesn't work :(

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  • Best way to update/insert into a table based on a remote table.

    - by martilyo
    I have two very large enterprise tables in an Oracle 10g database. One table keeps the historical information of the other table. The problem is, I'm getting to the point where the records are just too many that my insert update is taking too long and my session is getting killed by the governor. Here's a pseudocode of my update process: sqlsel := 'SELECT col1, col2, col3, sysdate FROM table2@remote_location dpi WHERE (col1, col2, col3) IN ( SELECT col1, col2, col3 FROM table2@remote_location MINUS SELECT DISTINCT col1, col2, col3 FROM table1 mpc WHERE facility = '''||load_facility||''' )'; EXECUTE IMMEDIATE sqlsel BULK COLLECT INTO table1; I've tried the MERGE statement: MERGE INTO table1 t1 USING ( SELECT col1, col2, col3 FROM table2@remote_location ) t2 ON ( t1.col1 = t2.col1 AND t1.col2 = t2.col2 AND t1.col3 = t2.col3 ) WHEN NOT MATCHED THEN INSERT (t1.col1, t1.col2, t1.col3, t1.update_dttm ) VALUES (t2.col1, t2.col2, t2.col3, sysdate ) But there seems to be a confirmed bug on versions prior to Oracle 10.2.0.4 on the merge statement when doing a merge using a remote database. The chance of getting an enterprise upgrade is slim so is there a way to further optimize my first query or write it in another way to have it run best performance wise? Thanks.

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  • Suggestion on Database structure for relational data

    - by miccet
    Hi there. I've been wrestling with this problem for quite a while now and the automatic mails with 'Slow Query' warnings are still popping in. Basically, I have Blogs with a corresponding table as well as a table that keeps track of how many times each Blog has been viewed. This last table has a huge amount of records since this page is relatively high traffic and it logs every hit as an individual row. I have tried with indexes on the fields that are included in the WHERE clause, but it doesn't seem to help. I have also tried to clean the table each week by removing old ( 1.weeks) records. SO, I'm asking you guys, how would you solve this? The query that I know is causing the slowness is generated by Rails and looks like this: SELECT count(*) AS count_all FROM blog_views WHERE (created_at >= '2010-01-01 00:00:01' AND blog_id = 1); The tables have the following structures: CREATE TABLE IF NOT EXISTS 'blogs' ( 'id' int(11) NOT NULL auto_increment, 'name' varchar(255) default NULL, 'perma_name' varchar(255) default NULL, 'author_id' int(11) default NULL, 'created_at' datetime default NULL, 'updated_at' datetime default NULL, 'blog_picture_id' int(11) default NULL, 'blog_picture2_id' int(11) default NULL, 'page_id' int(11) default NULL, 'blog_picture3_id' int(11) default NULL, 'active' tinyint(1) default '1', PRIMARY KEY ('id'), KEY 'index_blogs_on_author_id' ('author_id') ) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=1 ; And CREATE TABLE IF NOT EXISTS 'blog_views' ( 'id' int(11) NOT NULL auto_increment, 'blog_id' int(11) default NULL, 'ip' varchar(255) default NULL, 'created_at' datetime default NULL, 'updated_at' datetime default NULL, PRIMARY KEY ('id'), KEY 'index_blog_views_on_blog_id' ('blog_id'), KEY 'created_at' ('created_at') ) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=1 ;

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  • Showing multiple models in a single ListView

    - by Veer
    I've three models (Contacts, Notes, Reminders). I want to search all these and produce the filtered result in a single listview and depending upon the selection I've to display the corresponding view(UserControl) to its right. I want the right way of implementing the design or atleast alternatives to this method that I've tried. Now I've tried it using a IntegratedViewModel having all the properties from all the three models. public class IntegratedViewModel { ContactModel _contactModel; NoteModel _noteModel; public IntegratedViewModel(ContactModel contactModel) { _contactModel = contactModel; } // similarly for other models also public string DisplayTitle // For displaying in ListView { get; //same as set set { If(_contactModel != null) return _contactModel.Name; If(_noteModel != null) return _noteModel.Title; } } // All other properties from the three models includin the Name/Title properties for displaying them in the corresponding views(UserControl) } Now I set the itemsSource as the List<IntegratedViewModel>. I've to now bind the visibility of the views to some properties in the MainViewModel. I tried setting bool properties like IsContactViewSelected, IsNoteViewSelected using the setter of SelectedEntity property which is bound to the ListView's SelectedItem. public SelectedEntity { //get set { oldvalue = _selectedEntity; _selectedEntity = value; // now i find the Type of model selected using oldvalue.ModelType // where ModelType is a property in the IntegratedViewModel // according to the type, i set one of the above bool properties to false // and do the same for _selectedEntity but set the property to true // so that the view corresponding to the selectedEntityType is visible // and others are collapsed } } Here is the problem: For eg: let us say, I selected an item of type ContactModel, the old selection being NoteModel. I set the property IsNoteModelSelected to false according to the oldvalue, it sets the property and then Raises the propertychanged event and does not go and check the remaining if condition where i check for _selectedEntity which is used to set the IsContactModelSelected to true.

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