| Groups | Blog | Home |
dotnet general : ADO.net: 3 Data Set Questions (Issues)
[quoted text, click to view] "Mr. B" <User@NoWhere.com> wrote in message news:ruird0l5usc5b1pdqb99fns1c5r8g6f4o5@4ax.com... > I'm updating my current VB.et application. I currently reads about 6 tables > from an MS Data base. I've created a new MDB file which combines the 6 tables > into 1 table. I'm doing this because I know I'll speed up my application > loading time by more than 10 seconds (out of about 20). > > I've run across three situations in which I'm stuck at: > > Issue One: > > If my largest Column has (say) 200 lines, other columns will have less data > lines. So say Column 1 has 50 lines of data, column 2 has 200 lines and > column 3 has 150 lines. Then column 1 and 3 will have lines containing > nothing (ie null or blank lines). > > How to I test for a 'null' in a FOR statement? This is so that I can tell > when I've hit the end of my data for that column? > > > Issue Two: > > For the above, How can I get rid of any blank lines when I bind the Datasource > to a ComboBox pull down? Column 3 will have 50 lines of blank. So if I sort > a ComboBox, the first 50 lines are blank! :( > > > Issue Three: > > I've several ComboBox pulldowns which are bind to the same data set. But if I > change one, then the all change! How can I control them independantly? > > For example, if I have 6 ComboBoxes. They are all bound to the same Data > Source, but each one is bound to a different Member of that Data Source. > > So say I want to have 1 and 2 related (one changes, so does the other)... then > 3 and 4 paired together similar as 1 and 2, and 5 and 6 completely independant > from all the others? > > Mucho Appreciated! > > Bruce
I'm updating my current VB.et application. I currently reads about 6 tables
from an MS Data base. I've created a new MDB file which combines the 6 tables into 1 table. I'm doing this because I know I'll speed up my application loading time by more than 10 seconds (out of about 20). I've run across three situations in which I'm stuck at: Issue One: If my largest Column has (say) 200 lines, other columns will have less data lines. So say Column 1 has 50 lines of data, column 2 has 200 lines and column 3 has 150 lines. Then column 1 and 3 will have lines containing nothing (ie null or blank lines). How to I test for a 'null' in a FOR statement? This is so that I can tell when I've hit the end of my data for that column? Issue Two: For the above, How can I get rid of any blank lines when I bind the Datasource to a ComboBox pull down? Column 3 will have 50 lines of blank. So if I sort a ComboBox, the first 50 lines are blank! :( Issue Three: I've several ComboBox pulldowns which are bind to the same data set. But if I change one, then the all change! How can I control them independantly? For example, if I have 6 ComboBoxes. They are all bound to the same Data Source, but each one is bound to a different Member of that Data Source. So say I want to have 1 and 2 related (one changes, so does the other)... then 3 and 4 paired together similar as 1 and 2, and 5 and 6 completely independant from all the others? Mucho Appreciated!
If you are binding to a datasource that has the blanks within, the easiest
way is to prevent the blanks from populating when you initially pull the data. A lot of different ways of writing your query to do that, but basically do not return the null cells. If you are using a stored procedure, one way is to write subqueries for each field to filter out the nulls/empty cells. [quoted text, click to view] "Mr. B" <User@NoWhere.com> wrote in message news:16vrd0ddliruqv2envnr4kmv9dqthp2pk8@4ax.com... > With Deft Fingers, "Earl" <brikshoe@newsgroups.nospam> wrote: > > > IsDbNull and use a DataView for each combo > > Well... that solved all but Issue Two: > > > Issue Two: > > > > For the above, How can I get rid of any blank lines when I bind the > >Datasource to a ComboBox pull down? Column 3 will have 50 lines of blank. So if I > >sort a ComboBox, the first 50 lines are blank! :( >
[quoted text, click to view]
With Deft Fingers, "Earl" <brikshoe@newsgroups.nospam> wrote: > IsDbNull and use a DataView for each combo Excellent... I got the DataView working fine! Just have to work more on the IsDbNull part. But thanks for pointing me in the right direction! Regards,
[quoted text, click to view]
With Deft Fingers, "Earl" <brikshoe@newsgroups.nospam> wrote: > IsDbNull and use a DataView for each combo Well... that solved all but Issue Two: [quoted text, click to view] > Issue Two:
> > For the above, How can I get rid of any blank lines when I bind the >Datasource to a ComboBox pull down? Column 3 will have 50 lines of blank. So if I >sort a ComboBox, the first 50 lines are blank! :(
The datasource contains the "blanks" (empty string). The easiest way to deal
with that is to prevent it at the time you read in the data from the database. Alternatively, you have to filter that out of your dataview. Take a look at this post: http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&threadm=udVnkBvTEHA.504%40TK2MSFTNGP11.phx.gbl&rnum=2&prev=/groups%3Fhl%3Den%26lr%3D%26ie%3DUTF-8%26scoring%3Dd%26q%3Ddataview%252Bfilter%252Bempty%26meta%3Dgroup%253Dmicrosoft.public.dotnet.framework.adonet [quoted text, click to view] "Mr. B" <User@NoWhere.com> wrote in message news:kvfsd0lainkaeilrm5ku5krjs1vg566r3b@4ax.com... > With Deft Fingers, "Earl" <brikshoe@newsgroups.nospam> wrote: > > >If you are binding to a datasource that has the blanks within, the easiest > >way is to prevent the blanks from populating when you initially pull the > >data. A lot of different ways of writing your query to do that, but > >basically do not return the null cells. If you are using a stored procedure, > >one way is to write subqueries for each field to filter out the nulls/empty > >cells. > > hmm... not 100% I'm sure what you mean... but I'll try playing with Filters > and see where I go/get. I don't recall seeing anything on this in my books... > but I'll look. > > Thanks (again)! > > Bruce
[quoted text, click to view]
With Deft Fingers, "Earl" <brikshoe@newsgroups.nospam> wrote: >If you are binding to a datasource that has the blanks within, the easiest >way is to prevent the blanks from populating when you initially pull the >data. A lot of different ways of writing your query to do that, but >basically do not return the null cells. If you are using a stored procedure, >one way is to write subqueries for each field to filter out the nulls/empty >cells. hmm... not 100% I'm sure what you mean... but I'll try playing with Filters and see where I go/get. I don't recall seeing anything on this in my books... but I'll look. Thanks (again)!
[quoted text, click to view]
With Deft Fingers, "Earl" <brikshoe@newsgroups.nospam> wrote: >The datasource contains the "blanks" (empty string). The easiest way to deal >with that is to prevent it at the time you read in the data from the >database. Alternatively, you have to filter that out of your dataview. Take >a look at this post: > >http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&threadm=udVnkBvTEHA.504%40TK2MSFTNGP11.phx.gbl&rnum=2&prev=/groups%3Fhl%3Den%26lr%3D%26ie%3DUTF-8%26scoring%3Dd%26q%3Ddataview%252Bfilter%252Bempty%26meta%3Dgroup%253Dmicrosoft.public.dotnet.framework.adonet Easier said than done (: I looked at your example from above... but I dont' see how I can apply it :( I've spent the last many hours searching the web on filtering... but they all give great fitering information... except how to get Rid of Null values :( One that looked promising was: If you want to filter rows with null values, you must first convert the null values to something such as a string: dv.RowFilter = "Isnull(Col1,'Null') = 'Null'" But that too didn't do too much... oh well.. might as well fall back and throw the info into a Listbox, delete the blanks and then fire the info to my Comboboxes... A crappy way to do it, but at least I know how to do that. This just seems way over my head (which is hurting now) (: Thanks anyways...
[quoted text, click to view]
With Deft Fingers, "Earl" <brikshoe@newsgroups.nospam> wrote: >The datasource contains the "blanks" (empty string). The easiest way to deal >with that is to prevent it at the time you read in the data from the >database. Alternatively, you have to filter that out of your dataview. Take >a look at this post: Well... I think I got it... I found this posting: http://www.akadia.com/services/dotnet_filter_sort.html It said: To return only those columns with null values, use the following expression: "Isnull(Col1,'Null Column') = 'Null Column'" .... So I just turned the Equal sign to Inequal (<>)... and it looks like it solved my problem! All the references to NULL's are no longer there in my pulldows! Just the hard data!!! My full code for one combo (cmbUserID) is as follows (where 'Employee' is the column in the Table TSUpdate): Dim usr1 As DataView = New DataView(DsTSUpdate.Tables("TSUpdate")) usr1.RowFilter = "Isnull(Employee,'Null Column') <> 'Null Column'" cmbUserID.DataSource = usr1 cmbUserID.DisplayMember = "Employee" Regards,
Don't see what you're looking for? Try a search.
|
June 2003
July 2003
August 2003
September 2003
October 2003
November 2003
December 2003
January 2004
February 2004
March 2004
April 2004
May 2004
June 2004
July 2004
August 2004
September 2004
October 2004
November 2004
December 2004
January 2005
February 2005
March 2005
April 2005
May 2005
June 2005
July 2005
August 2005
September 2005
October 2005
November 2005
December 2005
January 2006
February 2006
March 2006
April 2006
May 2006
June 2006
July 2006
August 2006
September 2006
October 2006
November 2006
December 2006
January 2007
February 2007
March 2007
April 2007
May 2007
June 2007
July 2007
August 2007
September 2007
October 2007
November 2007
December 2007
January 2008
February 2008
March 2008
April 2008
| home · blog · groups | Questions? Comments? Contact the dn |