Android Question ExecQuerySingleResult generates Invalid double: "null"

[Gary Milne]

I'm running a query against SQL to see if a record exists (so it can be updated). The query is quite simple and looks like "SELECT MAX (ShotNumber) FROM SESSION WHERE SessionNumber = 3 AND RallyNumber = 25"

When it does not exist (which is quite common) then I get a java.lang.NumberFormatException: Invalid double: "null"

Other B4A SQL routines will usually say something like "this is a sql exception not an error", but this error does not, so it concerns me.

I have it in a Try Catch loop but if there is a better way I'd like to know what it is.

Thanks for any responses.

 

[DonManfred]

without seeing a code it is hard to help.
i would suggest that you first try to check the amount of resulting rows (Recordcount >0) . And only if >0 then you assign the 0th element. To double-check you can check if cursor(0) <> null

 

[Erel]

Your code should be:

Dim res As String = SQL1.ExecQuerySingleResult(...)
If res <> Null Then
 Dim value As Int = res
 ...
End If

 

[mc73]

An alternative to Erel's code, in the particular query, could be

SELECT ifnull(MAX (ShotNumber),0) FROM SESSION WHERE SessionNumber = 3 AND RallyNumber = 25

. This will return 0, if the field's value is null.

 

[Gary Milne]

Thanks for those responses. I'm using an Int to capture the response but it makes sense that the response would be a string which can be converted to a different type. I'll try that tomorrow.

Many thanks everyone who took the time.

 

[Gary Milne]

Thanks all, that did the trick.