query in Vba using cdate function with variable - sql

Question

Using the following query in microsoft access sql view works nice and easy with a hard coded date
SELECT Salary.First, Salary.Last,FROM Salary, allowances
WHERE Salary.PayThroughDate = CDate("2014-05-06") AND Salary.SSN = allowances.SSN
but embedding this query in Vba using a variable instead of a hard coded date is another business. It is just not working:
Dim ddate As Variant
Dim getDay As Integer
Dim getMonth As Integer
Dim getYear As Integer
getDay = Day(Me.DTPicker2.Value)
getMonth = Month(Me.DTPicker2.Value)
getYear = Year(Me.DTPicker2.Value)
ddate = getDay & "/" & getMonth & "/" & getYear
ddate = Format(ddate, "dd/mm/yyyy")
query1 = "SELECT Salary.First, Salary.Last FROM Salary, allowances WHERE Salary.PayThroughDate = " & CDate(ddate) & " AND Salary.SSN =
allowances.SSN
Any ideas in this Vba Sql mix? Am I missing single or double quotes?

Answer 1

When you send the SQL directly to JET and not running it from the normal user-interface of MS Access, you will need to make the date-format in the American format. I have had this problem a lot long time ago, but solved it by using this function to format my date in to text, the way that JET expects it to be:
Function SQLDate(varDate As Date) As String
'---------------------------------------------------------------------------------------
'Purpose Formats a date in the american way so that it can be used in
' SQL (by the JET-engine)
'Accepts varDate - the date that should be converted to text
'Returns The date converted to text, in american format with both the day and
' the month using 2 characters. (01 is january)
'---------------------------------------------------------------------------------------
'Changelog
'HANY 20100407: Stopped using the FORMAT-function for the date-value, as I found some
' cases where the format did not return the date as specified.
'---------------------------------------------------------------------------------------
'SQLDate = "#" & Format$(varDate, "mm\/dd\/yyyy") & "#"
SQLDate = "#" & Format(Month(varDate), "00") & "/" & Format(Day(varDate), "00") & "/" & Format(Year(varDate), "0000") & "#"
End Function
In your example above, you now add the date like this & SQLDate(CDate(ddate)) & instead of & CDate(ddate) &

Answer 2

The equivilant query is:
query1 = "SELECT Salary.First, Salary.Last
FROM Salary, allowances
WHERE (Salary.PayThroughDate =Cdate(" & ddate & ") )
AND (Salary.SSN = allowances.SSN)"
The problem you had is that when you constructed the sql string, the cdate value was converted into a string value first. It was just the same as
WHERE (Salary.PayThroughDate =" & format(ddate,"general date") & ")
If you do the cdate conversion later it works. Another almost equivilant query is
...
WHERE Salary.PayThroughDate =#" & ddate & "#
...
Both Cdate and the # tags take a string date, and convert to a date type (using slightly different rules). Since a date type is actually stored as the integer part of a double, you can also do:
WHERE Salary.PayThroughDate =cdbl(#" & ddate & "#)
or
WHERE Salary.PayThroughDate =clng(#" & ddate & "#)
or
WHERE Salary.PayThroughDate =" & clng(cdate(ddate) & "
--the number will be converted into a string to be part of the sql string, but numbers work correctly in SQL: they don't need to have # tags or conversion functions to make them work.
but you started out with a date value:
v =Me.DTPicker2.Value
so you can convert that directly to a number without converting it to a string first:
d = clng(Me.DTPicker2.Value)
...
WHERE (Salary.PayThroughDate = " & d & ")
which is the fastest and least error prone of handling dates in Access/VBA, but comes undone when you start working with SQL server, which stores dates differently.
Also, I see that you correctly used ISO date format when constructing your test example, but switched to American date format when constructing a string from the date value. That was a mistake. To avoid errors and 'evil date guessing' in SQL, you should stick to the ISO format:
v =Me.DTPicker2.Value
sdate = format(v,"yyyy-mm-dd")