Run-time error '94' Invalid use of Null

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Need advice on the structure of students table..interest on enrolled column(datatype) for sql server 2005. I also need advice on the use of the datatype for which my function is declared. My enrolled column currently has bit datatype. Am getting the error above what could be the problem.

VB

Public Function GetEnrolled() As Boolean
If Rs.State = adStateOpen Then Rs.Close
sql = " SELECT Students.Enrolled From Students WHERE Students.sID='" & vOldIDNumber & "' and students.yrlevel='" & voidYearlevel & "' and students.scourse='" & voidCourse & "' and semester='" & voidSem & "'"
   Rs.Open sql, RSconn
   If Not Rs.EOF Then
   GetEnrolled = Rs(0).Value
   End If
End Function

Posted 24-Apr-13 5:35am

Aleu Philip

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CHill60 24-Apr-13 12:00pm

What is actually in Rs(0) ... I think it might be Null which can't be mapped to a boolean ... I usually use a char(1) not null column for bools (defaulting to N) but you can get around the problem here without changing the database by wrapping the assignment to GetEnrolled in an if-statement

Aleu Philip 24-Apr-13 12:08pm

R(0) is actually null going to try your suggestion

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Maciej Los · Answer 1 · 2013-04-24T10:27:00

Steps to do:
1) create and open connection
2) create and open Recordset object
3) while recordset not EOF, read values

VB

Dim oConn As ADODB.Connection
Dim sConn As String 
Dim oRst As ADODB.Recordset
Dim sSQL As String

sConn = "Your connection"

Set oConn = New ADODB.Connection
oConn.Open sConn

Set oRst = New ADODB.Recordset
sSQL = "your query"
rstEmployees.Open sSQL, oConn, adOpenStatic, adLockOptimistic, adCmdTable

Do While Not oRst.EOF
    MsgBox oRst.Fields(0).Value
    .MoveNext
Loop

See more:
Open Method (ADO recordset)[^]
Open and Close Methods Example (VB)[^]
MoveFirst, MoveLast, MoveNext, and MovePrevious Methods Example (VB)[^]

agent_suwastica · Answer 2 · 2013-05-09T21:28:00

Solution 2

Use this

GetEnrolled = IIf(IsNull(Rs(0).Value), "", Rs(0).Value)

Posted 9-May-13 21:28pm

agent_suwastica