Saving a SQL result that has multiple data being read from a Microsoft Access database - sql

Question

I'm trying to send a email with multiple data from an SQL statement but I can't get the result of the SQL statement to be saved in the variable.
str = "SELECT Test.*,TestTopicScore.[Easy Question Score],TestTopicScore.[Medium Question Score],TestTopicScore.[Hard Question Score] from Test INNER JOIN TestTopicScore on Test.TestID = TestTopicScore.TestID ORDER BY Test.Score DESC"
mycommand = New OleDbCommand(str, myconnection)
myReader = mycommand.ExecuteReader
myReader.Read()
emailcontents = myReader("emailcontents")
The connection with the access database is fine and the data is read but i just cant get it to save in a variable.
The error I get:
An unhandled exception of type 'System.IndexOutOfRangeException' occurred in System.Data.dll
Additional information: emailcontents

Answer 1

Let's look at your query first, I've formatted it a bit to make it easier to see what's going on:
SELECT Test.*
,TestTopicScore.[Easy Question Score]
,TestTopicScore.[Medium Question Score]
,TestTopicScore.[Hard Question Score]
FROM Test
INNER JOIN TestTopicScore
ON Test.TestID = TestTopicScore.TestID
ORDER BY Test.Score DESC
What that is doing is selecting several different fields, not one value. Your code emailcontents = myReader("emailcontents") attempts to read one field which is named "emailcontents". Unfortunately, there is no such named field.
It is worse than that: you don't even know how many fields Test.* is going to return.
So, start by enumerating every field which you want from Test.
Then, you appear to want just one string as the result, so you will need to concatenate the fields as strings instead of returning them separately.
In Access, the operator to join strings together is &, and it should convert numeric values into strings for you, thus:
SELECT Test.SomeField & Chr(13) & Chr(10)
& Test.SomeOtherField
& Test.AnotherField
& TestTopicScore.[Easy Question Score]
& TestTopicScore.[Medium Question Score]
& TestTopicScore.[Hard Question Score]
AS [emailcontents]
FROM Test
INNER JOIN TestTopicScore
ON Test.TestID = TestTopicScore.TestID
ORDER BY Test.Score DESC
Notice how I put & Chr(13) & Chr(10) between Test.SomeField and Test.SomeOtherField: that puts in a new line between the two. You might want to do it in between all the fields.
Also, I gave a name to the concatenated data with AS.
Now we're getting into really messy stuff by having to put the formatting of the output into the database. You don't want to do that. Let me emphasise this so it stands out: A better way is to read all the fields individually in your VB.NET code and format them into a string there.
ETA: Not only all that, but it looks like you might return more than one set of results (from seeing the ORDER BY), in which case you will have to read all the results in a loop.