Database not saving record

M

mleffler

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I'm using Margaret's Db code and have setup two databases. It is very handy for what I am doing. One for readings and one for settings.
It seems the settings one does not store the record correctly.

Sub Set_SettingsDb
db.Pointer = -1
db.FileName = "settings.dat"
db.Field(0,0) = "servername" :db.Field(0,1)=50
db.Field(1,0) = "serverport" :db.Field(1,1)=10
db.Field(2,0) = "username" :db.Field(2,1)=50
db.Field(3,0) = "password" :db.Field(3,1)=20
db.Field(4,0) = "toaddress" :db.Field(4,1)=50
db.Field(5,0) = "subject" :db.Field(5,1)=50
db.Field(6,0) = "body" :db.Field(6,1)=100
db.Field(7,0) = "" :db.Field(7,1)=0
End Sub
Sub Set_ReadingsDb
db.Pointer = -1
db.FileName = "readings.dat"
db.Field(0,0) = "serialnumber" :db.Field(0,1)=20
db.Field(1,0) = "reading1" :db.Field(1,1)=10
db.Field(2,0) = "reading2" :db.Field(2,1)=10
db.Field(3,0) = "reading3" :db.Field(3,1)=10
db.Field(4,0) = "reading4" :db.Field(4,1)=10
db.Field(5,0) = "dateread" :db.Field(5,1)=30
db.Field(6,0) = "datapacket":db.Field(6,1)=30
db.Field(7,0) = "" :db.Field(7,1)=0
End Sub

I setup the two Subs above to switch between them and they seem to work Ok. The problem seems to be when I leave the program and then go back in. The Settings are first read into the program, but they dont exist when I go back in.

Am I doing something wrong or should I store the database someplace other than dir.Internal?

I have tried this on the emulator and a tablet, they both do the same thing.
I did notice that when I run this in the debugger the Settings database when first opened always has 0 records no matter how many times I start a new debug session. I assume this is normal for the debugger.

Any ideas on what could be going on would be helpful.
 
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M

mleffler

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Longtime User
More information on database issue.

Sub ExitSettingsButton_Click
Dim ServerString As String
Dim PortString As String
Dim UserNameString As String
Dim PasswordString As String
Dim ToAddressString As String
Dim SubjectString As String
Dim EmailBodyString As String

Set_SettingsDb
ReadingsFlag = 0

'Save Settings to database record.
ServerString = ServerText.Text
PortString = PortText.Text
UserNameString = UserNameText.Text
PasswordString = PasswordText.Text
ToAddressString = ToAddressText.Text
SubjectString = SubjectText.Text
EmailBodyString = EmailBody.Text
db.Field(0,0) = ServerString
db.Field(1,0) = PortString
db.Field(2,0) = UserNameString
db.Field(3,0) = PasswordString
db.Field(4,0) = ToAddressString
db.Field(5,0) = SubjectString
db.Field(6,0) = EmailBodyString

If db.RecordCount = 0 Then
db.AddRecord()
Else
db.UpdateRecord()
End If

What I want to happen is that if the record exists it should update the record otherwise it will create a new record.
What I am seeing is the at the start of this right after the Set_SettingsDb the db.RecordCount is 0. At the end of this sub the db.RecordCount = 6 or 7 or some other number. It should be one since I am only adding one record.

The text is just whatever the user enters in text fields on a screen.

I have used the db library before without any issues so I dont know what is going on. This is however the first time I used it with more than one database in a program.

Thanks for any help you can provide.
F.Y.I. I am using version 1.6 of the code.
 
Upvote 0

margret

Well-Known Member
Licensed User
Longtime User
Hello,

I see your problem. The pointer from the start will equal -1. This is it's value before the database is created. The pointer only gets updated once records have been saved. So the code that you had will never add a new record. Try this code and it should work:

B4X: 
If db.RecordCount < 1 Then
      db.AddRecord()
Else
      db.UpdateRecord()
End If
 
Upvote 0
M

mleffler

Member
Licensed User
Longtime User
Found the solution

I finally figured out what is going on.

It seems that if I change the database structure. For example if you go from 7 fields to 5 fields the structure wont change in any already used database.

For example I set up "readings.dat" with 7 fields then run a debug session. Next I remove 2 fields and run another session. The database will still be 7 fields in size and of course will not work. It seems to persist even if I go out of Basic4Android then back in.

However if I rename the database file to "readings2.dat" the database will have 5 fields and work correctly. It seems that any existing database once used can not be restructured. Or I haven't figured out how anyway.

I did not see a function like that anyway.

Renaming the "settings.dat" to "settings2.dat" seems to have fixed the problem I was having.
 
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