.NET (Core and Framework)

hendrikbez13-Apr-09 22:26

13-Apr-09 22:26

even if I use this

MyOledbCommand.CommandText = "UPDATE Tblokkies SET leidraad = @string1, A1 = @string2, A2 = @string3, A3 = @string4,A4 = @string5, A5 = @string6, A6 = @string7, A7 = @string8, A8 = @string9, A9 = @string10, A10 = @string11, A11 = @string12, A12 = @string13"

I can not get it to save to the database

Eddy Vluggen13-Apr-09 23:11

13-Apr-09 23:11

I think that the WHERE part would be moved to the end of the statement, and you might want to check the parameters;

"UPDATE Tblokkies 
   SET A1  = @string2, 
       A2  = @string3, 
       A3  = @string4, 
       A4  = @string5, 
       A5  = @string6, 
       A6  = @string7, 
       A7  = @string8, 
       A8  = @string9, 
       A9  = @string10, 
       A10 = @string11, 
       A11 = @string12, 
       A12 = @string13 
 WHERE leidraad = @string1"

Enjoy

I are troll Smile | :)

hendrikbez13-Apr-09 23:59

13-Apr-09 23:59

Thanks, now I am getting a answer back, that it did not save it to database,
before, I did not get anyting back

Edit

Ps sometimes it says that is have saved the info, but there it did not sdaved it in the data base

Eddy Vluggen14-Apr-09 1:13

14-Apr-09 1:13

hendrikbez wrote:
Ps sometimes it says that is have saved the info, but there it did not sdaved it in the data base

That might happen when there are no records matching the parameter @string1; in that case it will return with succes, since it updated all records matching the criteria (iow, no records at all).

Try the query outside of your code, and verify whether it works as intended Smile | :)

I are troll Smile | :)

hendrikbez14-Apr-09 1:33

14-Apr-09 1:33

My string1 and string2 will always have info in, I only want to add string3 today, and later string4 and so on, so when I click on my listbox it chooses the info and put it in my textboxers, then I add a new word to string3, then it must update, but it don't

Eddy Vluggen14-Apr-09 6:16

14-Apr-09 6:16

It will only update the row in the table that has "@string1". That means that the row has to exist before you can update it. Can you put a breakpoint there and verify that "string1" is filled with the correct key?

In other words, I'm interested in the values that you're writing to the database.

I are troll Smile | :)

hendrikbez14-Apr-09 23:24

14-Apr-09 23:24

With my Breakpoint.

1. Click on button "Edit info"
2. Say I must choose a leidraad to edit
3. Choose number 4 from listbox

On this code

Private Sub ListBox1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ListBox1.SelectedIndexChanged

        Dim SqlStr As String

        SqlStr = "Select * from tblokkies where leidraad = """ & ListBox1.Items(ListBox1.SelectedIndex) & """"

        FillTextBox(SqlStr)
    End Sub

On F8

SqlStr = "Select * from tblokkies where leidraad = """ & ListBox1.Items(ListBox1.SelectedIndex) & """"
SqlStr ========"Sqltr "Select *from tblokkies where leidraad = "'n uitroep""
ListBox1.SelectedIndex)=========="Listbox1.Seletectedindex 3

FillTextBox(SqlStr) ========"Filltextbox Nothing

It then fills my textboxes with this info

4. info in this from row in my table ====Luidraad ='n uitroep" A1=gits, A2=aag,A3=SA (My textboxes luidraad,A1,A2,A3,)
Want to put info now in A4=test" (textbox A4)
4. Click on Save button.

On this code after F8

Private Sub btnAdd_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnAdd.Click

      If SaveOrEdit = "Save" Then

          Dim add As DialogResult

          add = Cls_MessageBbox.Show("Is jy Seker jy will Leidraad" & vbCrLf & vbCrLf & TxtLuidraad.Text & vbCrLf & vbCrLf & "Byvoeg", "Byvoeg.", MessageBoxButtons.YesNo, MessageBoxIcon.Question)

          If add = Windows.Forms.DialogResult.Yes Then
              AddNew()
          Else
              ListBox1.Text = "Geen leidraad is Bygevoeg nie"

          End If

      ElseIf SaveOrEdit = "Edit" Then

          Edit()
      Else

          StatusLabel.Text = " Geen Leidraad is bygevoeg"

      End If

  End Sub

If SaveOrEdit = "Save" Then =====Saveoredit ""
Then jumbs to
ElseIf SaveOrEdit = "Edit" Then =======Saveordeit ""
StatusLabel.Text = " Geen Leidraad is bygevoeg"=========Statuslabel.text "Leidradd :'n Uiroep: geselkteer"
After F8
StatusLabel.Text = " Geen Leidraad is bygevoeg"=========Statuslabel.text "Geen Leidraad is bygevoeg"

This is where it stops.

Eddy Vluggen15-Apr-09 0:11

Connecting C++.NET with WebService..

15-Apr-09 0:11

I understood that the btnAdd_Click handler is the save-button. Somehow it does trigger this for the first three textboxes (as you said they were saved correctly), but number four is out.

The variable SaveOrEdit hasn't got the value "Edit", which would trigger the Edit() function. The question remains why it works for the first three textboxes differently then for the fourth.

It 'feels' like there's something wrong with the program-flow, but I can't point where the pain precisely is Sigh | :sigh:

I are troll Smile | :)

shaina223112-Apr-09 21:13

shaina2231

12-Apr-09 21:13

How its possible to Connect the Vc+.NET application with webservice.
i want to Post the Values of Some fields on Submit button clicking To WebService( designed in c#.NET)
What type of project should i take either MFC or else plz guide

Database connection

EmZan11-Apr-09 2:21

11-Apr-09 2:21

i'm wondoring which is better !!

1.openning the connection to the database and leaving it opened untill the application is closed.

2.closing that connection and openning it again when i a need to connect
,which means i will open and close the connection many times while the application is running !!

thanks in advance

0x3c011-Apr-09 2:41

0x3c0

11-Apr-09 2:41

Just a technical point: assuming that the connection is by the same program to the same file, the connection doesn't get closed and opened lots of times. Most database drivers use connection pooling, which caches the database connection. This increases the speed considerably

Personally, I would go with the second option. I don't write database programs often, but with the advent of connection pooling, the speed reduction is virtually eliminated. On the other hand, a program may terminate abnormally; an example of this would be the 'End Process' button in Task Manager. If that happens, I don't know if the connection would get terminated

This choice is just my opinion really. It may not be right, but it goes with my general method of retrieving data: get in, read it as quickly and efficiently as possible, get out, deal with the extracted data

EmZan11-Apr-09 3:01

11-Apr-09 3:01

thanks for ur reply ,

but i didn't get the meaning of connection pooling !
and what is the advantage?

i thought about it ,
i think if the program depends on a database which is on pc other than the application pc , it may be better if i use option 2 because of network traffic and security issues

beside if the database is on the application pc itself i would use option 1
that is my opinion and am not sure if it is better

0x3c011-Apr-09 3:17

0x3c0

11-Apr-09 3:17

Connection pooling basically caches the connection. It removes most of the overhead from creating a connection. Most of the database drivers use it. The main advantage of this is speed; there's no need to create a connection and read the data when the database driver's got some of the data already cached

EmZan11-Apr-09 6:15

11-Apr-09 6:15

oh yee i got it

it remembers me deferred execution Linq in .net3.5
deferred execution doesn't have connection pooling Smile | :)

thanks a lot

Colin Angus Mackay11-Apr-09 6:25

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11-Apr-09 6:25

Member 4697348 wrote:
it [connection pooling] remembers me deferred execution Linq in .net3.5

What has deferred execution got to do with connection pooling?

EmZan12-Apr-09 20:58

12-Apr-09 20:58

deferred execution doesn't keep data retrieved from database at RAM
so at every time you need somthing u will get the database data not the memory data

that is good when ur database is being updated a lot
which is an advantage of linq

Colin Angus Mackay12-Apr-09 22:57

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12-Apr-09 22:57

That was not my question. My question was "What has deferred execution got to do with connection pooling?"

While deferred execution has the effect you describe for LINQ to SQL, deferred execution is not about keeping whether the data is in RAM or not.

Deferred execution is about running the LINQ query at the point you want the data from it, not at the point you define the query. If you run your LINQ query on objects that exist only in RAM then it will filter based on the most recent state of the objects rather than the state they were in when you defined the query.

EmZan12-Apr-09 23:16

12-Apr-09 23:16

yes ,
but that is for link to objects

but in link to sql the linq queries deals directly with database
with no lookong for data at RAm at first.

am i right??

Colin Angus Mackay12-Apr-09 23:20

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12-Apr-09 23:20

EmZan wrote:
but that is for link to objects

It is for all types of LINQ. I used LINQ to Objects as an example of how it works when all the data is in RAM. The principle is the same regardless of where the data is. That was my point. I was expanding your definition as it was too narrow and dealt only with LINQ to SQL when your previous post simply mentions LINQ (without detailing what it was LINQing to).

You have still avoided my question on connection pooling. What does deferred execution in LINQ have to do with connection pooling?

EmZan12-Apr-09 23:36

12-Apr-09 23:36

as i understand from the obove discussion

connection pooling :
to keep track of last queried data cashed so that i will no use the database engine to execute a prev. executed query.
and that is done using the DataAdapter Object(which fills the DataSet Object)
and that what i got from ur prev reply

btw DataAdapter is automatically closes the connection after execution(reading or writing)

Deffered Execution :
as linq queries the data and stores it using a varible , then ther is no need for DataAdapter(the pooling hand).
and i'm sure that that variable will be removed after reaing the data ,and the connection is closed.
so there is no relation between conn-pooling and deff. exec. as i understand

Colin Angus Mackay12-Apr-09 23:52

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12-Apr-09 23:52

EmZan wrote:
connection pooling :
to keep track of last queried data cashed so that i will no use the database engine to execute a prev. executed query.

Nope. It keeps track of the previously query CONNECTION only so it doesn't have to reestablish a connection to the database. This makes it faster to establish a new connection. Any queries are done against the database, even if it is the same query as the previous time.

EmZan wrote:
and that is done using the DataAdapter Object(which fills the DataSet Object)
and that what i got from ur prev reply

I've never mentioned the DataAdapter. It is an evil thing.

EmZan wrote:
DataAdapter is automatically closes the connection after execution(reading or writing)

Well, it says it closes the connection, but just like everything else it simply returns it too the pool.

Connection Pooling happens on the SqlConnection object which everything that connects to a database must use. LINQ or not.

EmZan13-Apr-09 0:05

13-Apr-09 0:05

thanks for clarification ,it's realy a good info

but i have many questions plz

1.why did u call the data adapter an evil Confused | :confused:

i'm always using it in my application(actually my 4 applications)i'm a junior btw

2.u said that any query is done against the database!
what i know is that dataAdapters keeps queried data and i use it many times without going to the database again and again for the same query

and if it's wrong , i'd say that i read before at a limq tutorial that reading the most recent data is an advantage
that it means that there is a technology that reads old data many times without going to the database , as i mentioned Sigh | :sigh:

Colin Angus Mackay13-Apr-09 0:14

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13-Apr-09 0:14

EmZan wrote:
1.why did u call the data adapter an evil
i'm always using it in my application(actually my 4 applications)i'm a junior btw

Data Adapters are used to copy data into a DataSet or DataTable. These are large clunky constructs that almost always are under-utilised. So they end up taking more memory than they actually need for the job you use them for. The prefered solution is to take the data and put it in a domain model without the use of DataAdapters. LINQ to SQL goes some way to help achieve that easily. Previously you needed to use a DataReader (which a Data Adapters uses internally anyway) to get the data out and into your model.

EmZan wrote:
2.u said that any query is done against the database!
what i know is that dataAdapters keeps queried data and i use it many times without going to the database again and again for the same query

The Data Adapter dumps a disconnected copy of the data into a DataSet or DataTable. You are querying against that disconnected data. You never go back to the DataAdapter, you go back to the DataSet or DataTable. A DataAdapter's roll is to suck the data out of the database and make a copy of it. If it was a proper caching mechanism it would be relatively seamless. In otherwords you wouldn't know if it were cached or not.

EmZan13-Apr-09 2:11