I am having a look at IB Objects via the demo download, mostly for interest sake. I am hoping someone can explain why the following behaviour occurs. Apologies in advance if this is a stupid question.

I am using a DSQL component to run a singleton query which will return the key of a row if a given field matches my input parameter. All the prerequisites like connecting to the database have been performed.

The sql for the DSQL component looks like this:-

SELECT OBJID FROM TABLE_ACCOUNTS WHERE ACCOUNT_NAME = :NEWNAME

OBJID is the primary key value.

I prepare the query.

Then I set the parameter to a value to search for using:-

ParamByName('NEWNAME').AsString := AccName where AccName is a simple string containing the searched for account name.

I then execute the DSQL by calling the Execute method.

If there is a matching row then I get property RowsSelected = 1

If there is no matching row an exception occurs:-

'Attempt to fetch past the last record in a record stream'

This exception occurs during the Execute as far as I can tell. My next statement which looks at the value of RowsSelected is never executed.

What I expected to happen was that the value of the RowsSelected property would be = 0 rather than an exception.

Is this expected behaviour or have I missed something ? If expected behaviour then can I expect an exception to occur if I run SQL in other components that generate no selected rows ?

Mark Lawes

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