VBA&SQL - delete date range from database - sql

Question

I am trying to create an option on my Access database that deletes all records between 2 dates.
I code I have below does not seem to work consistently. For example, if my database has dates 01/01/18 to 01/30/18, and the range I specify is exactly 01/01/18 to 01/30/18, then it works and deletes all data.
But if I specify any other date range (like 01/01 - 01/15), it will fail and no records will be deleted.
The [Trade Date] is in short text format instead of date, but all the entries are in MM/DD/YY. Would prefer to keep it this way unless that is the issue and no other alternatives.
Please let me know what I am doing wrong or could do better. Thank you in advance.
Dim trFrmDat As String
Dim trToDat As String
Dim dbsDelete As DAO.Database
Dim qdfToDelete As DAO.QueryDef
Dim countString As String
Dim count As Long
Set dbsDelete = CurrentDb
trFrmDat = InputBox("Trade Date To Be Deleted From [MM/DD/YY]:")
trToDat = InputBox("Trade Date To Be Deleted To [MM/DD/YY]:")
If Len(trFrmDat) <> 8 Or Len(trToDat) <> 8 Then
MsgBox ("The correct date or answer has not been entered. Process Aborted.")
Exit Sub
Else
countString = "SELECT COUNT(PK_ID) FROM AR_Consolidated WHERE [Trade Date] BETWEEN " & trFrmDat & " AND " & trToDat & ""
count = dbsDelete.OpenRecordset(countString).Fields(0).Value
Set qdfToDelete = dbsDelete.CreateQueryDef("", "DELETE FROM AR_Consolidated WHERE [Trade Date] BETWEEN " & trFrmDat & " AND " & trToDat & "")
qdfToDelete.Execute dbFailOnError
MsgBox ("" & count & " records have been deleted from AR_Consolidated")
End If
EDIT:
I ended up using one of the suggestions below, but still had formatting issues with the date, so I conceded I cannot keep the actual field as short text. I just injected an alter line and everything works perfectly.
DoCmd.RunSQL "ALTER TABLE AR_Consolidated ALTER COLUMN [Trade Date] Datetime"

Answer 1

In order to represent a date value in Jet SQL, you need to surround it with #, such that your SQL ends up something like this:
DELETE FROM AR_Consolidated WHERE [Trade Date] BETWEEN #01/01/18# AND #01/30/18#
Note that in general, combining strings with user inputs to make SQL statements is a bad idea. Aside from issues similar to yours -- properly representing date or other literals in SQL statements -- you are also liable to SQL injection, where a malicious user inserts additional SQL statements or clauses that cause your code to fail or do something unwanted. For example, the user could pass in as the second parameter the following string:
01/01/18 OR 1 = 1
and the resulting SQL statement:
DELETE FROM AR_Consolidated WHERE [Trade Date] BETWEEN 01/01/18 AND 01/01/18 OR 1 = 1
would delete all the records in AR_Consolidated.
The correct way to avoid both classes of issues is to use parameterized queries.
Dim sql As String
sql = _
"PARAMETERS FromDate DATETIME, TillDate DATETIME; " & _
"DELETE FROM AR_Consolidated " & _
"WHERE [Trade Date] BETWEEN FromDate AND TillDate"
Dim qdfToDelete As DAO.QueryDef
Set qdfToDelete = dbsToDelete.CreateQueryDef("", sql)
qdfToDelete.Parameters("FromDate") = trFromDate
qdfToDelete.Parameters("TillDate") = trToDate
'You may have to convert the string values to dates first
qdfToDelete.Execute dbFailOnError
For a comprehensive description of how to avoid SQL injection when programming against Jet / ACE, see the Microsoft Access and COM / Automation pages on bobby-tables.com.

Answer 2

I would take a different approach and use parameters instead of string concatenation.
The query's SQL would be something like this:
PARAMETERS [prmDateFrom] DateTime, [prmDateTo] DateTime;
DELETE *
FROM AR_Consolidated
WHERE [Trade Date] Between [prmDateFrom] And [prmDateTo];
Then to call my query in VBA:
Sub Something()
Dim trFrmDat As String
Dim trToDat As String
trFrmDat = InputBox("Trade Date To Be Deleted From [MM/DD/YY]:")
trToDat = InputBox("Trade Date To Be Deleted To [MM/DD/YY]:")
If Len(trFrmDat) <> 8 Or Len(trToDat) <> 8 Then
MsgBox ("The correct date or answer has not been entered. Process Aborted.")
Exit Sub
End If
Dim qdf As DAO.QueryDef
Dim count As Long
Set qdf = CurrentDb().QueryDefs("QueryName")
With qdf
.Parameters("[prmDateFrom]").Value = CDate(trFrmDat)
.Parameters("[prmDateTo]").Value = CDate(trToDat)
.Execute dbFailOnError
count = .RecordsAffected
End With
MsgBox " " & count & " records have been deleted from AR_Consolidated"
End Sub
However, you need to enhance your input validation as a normal string with 8 characters which cannot be converted to a date would cause a runtime error.

Answer 3

You can validate the input and then format the values:
trFrmDat = InputBox("Trade Date To Be Deleted From [MM/DD/YY]:")
trToDat = InputBox("Trade Date To Be Deleted To [MM/DD/YY]:")
If IsDate(trFrmDat) And IsDate(trToDat) Then
trFrmDat = Format(CDate(trFrmDat), "yyyy\/mm\/dd")
trToDat = Format(CDate(trToDat), "yyyy\/mm\/dd")
countString = "SELECT COUNT(PK_ID) FROM AR_Consolidated WHERE [Trade Date] BETWEEN #" & trFrmDat & "# AND #" & trToDat & "#"
End If
and similar for the delete SQL.