How to get date name in MS-Access

I have 3 record:
day_birth of type Number (1-31);
month_birth of type Short Text ("January");
year_birth of type Number.

How to get in calculated field, full birthday day name from this day?

I tried this one expression:

WeekdayName(Weekday(DateSerial(2003;1;1);2))

But it doesn't work. I get #Type! in my record field.

Well, you can use this:

? format(dateserial(2003,1,1),"ddd")
Wed

or even this:

? format(dateserial(2003,1,1),"dddd")
Wednesday

However, you suggest/state/hint/imply/note that your input month is a LONG TEXT month of January. (short would be Jan).

So, we need to take into account that fact.

(but, why oh why oh why oh why oh why was the DOB not just stored as a simple single datetime column? With such a column, then you are 100% free to break it apart into 3 columns for reporting etc., but always have one simple date column

However, you have what you have, probably not your fault.

So, then:

Dim strTestMonth        As String
Dim intTestYear         As Integer
Dim intTestDay          As Integer

strTestMonth = "January"
intTestYear = 2003
intTestDay = 1

Dim strTestDate         As String
Dim strDateFormat       As String

strDateFormat = "mmmm/dd/yyyy"

strTestDate = strTestMonth & "/" & intTestDay & "/" & intTestYear

Dim dtDate              As Date

dtDate = Format(strTestDate, strDateFormat)


' get day of week as number
Debug.Print Weekday(dtDate)

' get day of week as text


Debug.Print "Short day of week = " & Format(dtDate, "ddd")

Debug.Print "Long day of week " & Format(dtDate, "dddd")

Output:

 4 
 Short day of week = Wed
 Long day of week Wednesday

So, approach:

Convert the string into a internal date, and once done, then you are free to spit out the date in any format you want, including use of weekday function, or even format which can return a short day format (wed), or a longer date format (Wednesday).

It not clear if you need this "display" of the week day on the form, or in a report or whatever. So as always the VERY important issue becomes the when/where/how/what point in time you need this expression.

So, you could for example place this function in a standard code module: (not forms code module)

Public Function GetDayOfWeek(strMonth As String, _
                            intDay As Integer, _
                            intYear As Integer) As String

    Dim strDateFormat   As String
    Dim dtDate          As Date
        
    strDateFormat = "mmmm/dd/yyyy"
    
    dtDate = Format(strMonth & "/" & intDay & "/" & intYear, strDateFormat)
    
    GetDayOfWeek = Format(dtDate, "dddd")
    

End Function

So, now when ever and "where" ever you need to display the weekday as "text", then you can do this for even a control on that form:

  =(GetDayOfWeek([MonthField],[dayField], [YearField]))

So, place the above code in a standard code module (not forms code module), and then in code, or even as a expression on a control in a form, you can pass the 3 values, and it will return/display the day of week in long text format.

Use DateValue and a simple query:

Select 
    *, 
    DateValue(Str([year_birth]) & " " & [month_birth] & Str([day_birth])) As BirthDate,
    WeekdayName(Weekday(DateValue(Str([year_birth]) & " " & [month_birth] & Str([day_birth])), 2), 2) As BirthWeekday
From 
    YourTable