Check if a specific record exists

This is an example of what I use to check if a user's email and employee number have already been used and presents a pop up alerting them.
dim rsEmail,rsEmployee,rsSchoolCode

set dal_table=dal.Table("dbo.AD_Security")

set rsEmail = dal_table.Query("Email='" & values("Email") & "'","")

set rsEmployee = dal_table.Query("Employee_Number='" & values("Employee_Number") & "'","")
if not rsEmail.eof then

Flush_output

Response.Write "<script>alert('Yikes! - The email address already exists. Please check your spelling/entry.')</script>"

elseif not rsEmployee.eof then

Flush_output

Response.Write "<script>alert('Yikes! - The Employee ID Number already exists. Please check your entry.')</script>"

elseif values("YourLocationFieldName")="" then

Flush_output

Response.Write "<script>alert('Yikes! - YourLocationFieldName does not have a valid entry.')</script>"

beforeadd = false

else

BeforeAdd = true
end if

Thanks for fast response,
I didn't explain this too well on the previous post,

I need to check all three fields together, i.e. it's O.K. to have duplicate name's and DOB's (even combined)but not when the location field is NULL
Basically, I have a view that displays locations that have not been assigned yet (i.e. location=NULL) it's on this view that I need to prevent duplication

(this is where the data is being inputted)
If a record that had the same "name" and "DOB" but did not have a location= NULL value that would not need to be checked.

It's a combination of all three together...

if joe bloggs, 12/08/1967, location=null (check this)

if joe bloggs, 12/08/1967, location=London (don't check this)
I hope this makes sense.

Would this work for you. Basically in the Before Record Added section in the events, if the location field is not blank, go ahead and add the record. If it is blank, check the fields and alert the user.
dim rsEmail,rsEmployee,rsSchoolCode

set dal_table=dal.Table("dbo.AD_Security")

set rsEmail = dal_table.Query("Email='" & values("Email") & "'","")

set rsEmployee = dal_table.Query("Employee_Number='" & values("Employee_Number") & "'","")
if values("YourLocationFieldName") <> "" then

BeforeAdd = true

else

if not rsEmail.eof then

Flush_output

Response.Write "<script>alert('Yikes! - The email address already exists. Please check your spelling/entry.')</script>"

elseif not rsEmployee.eof then

Flush_output

Response.Write "<script>alert('Yikes! - The Employee ID Number already exists. Please check your entry.')</script>"
beforeadd = false

else

BeforeAdd = true

end if

end if

Thanks Greg,

Nearly there, i have changed it a bit so the name and dob can be checked together.
dim rsname,rsdob,rsSchoolCode

set dal_table=dal.Table("dbo.client_table")
set rsname = dal_table.Query("name='" & values("name") & "' and dob='" & values("dob") & "'","")
if values("location") <> "" then

BeforeAdd = true

else

if not rsname.eof then

Flush_output

Response.Write "<script>alert('Yikes! - This record address already exists. Please check your spelling/entry.')</script>"
beforeadd = false

else

BeforeAdd = true

end if

end if
The validation for name and dob works fine
it's just the location does not,
I just replaced "YourLocationFieldName" with the field name "location" from my table "client_table"

if values("location") <> "" then (this checks for duplicates even if the location value is not NULL)
I changed if values("location") <> "NULL" then (this let's duplicates be added regardless of location field.)
Thanks...

Maybe it is something like this then:
dim rsname,rsdob,rsSchoolCode

set dal_table=dal.Table("dbo.client_table")
set rsname = dal_table.Query("name='" & values("name") & "' and dob='" & values("dob") & "'","")
if not rsname.eof and values("location") = "" then

Flush_output

Response.Write "<script>alert('Yikes! - This record address already exists. Please check your spelling/entry.')</script>"
beforeadd = false

else

BeforeAdd = true

end if

Hi Greg,
My new record has "location" defaulted to NULL, so I changed below because of that
if not rsname.eof and values("location") = "" then to if not rsname.eof and values("location") = "NULL" then
but it still does not catch the location = null
Thanks,

Mark.
dim rsname,rsdob,rsSchoolCode

set dal_table=dal.Table("dbo.client_table")
set rsname = dal_table.Query("name='" & values("name") & "' and dob='" & values("dob") & "'","")
if not rsname.eof and values("location") = "" then

Flush_output

Response.Write "<script>alert('Yikes! - This record address already exists. Please check your spelling/entry.')</script>"
beforeadd = false

else

BeforeAdd = true

end if

I made a test table and put the same information in and it worked. It worked with the double quotes symbolizing the field being empty. I also put in the Add page (in the visual editor) a default value of (the actual word) "NULL" and the action caught it.
As a recap/scenario, I have one existing record:
greg 11/01/1900 new york
If I enter:
greg 11/01/1900 NULL
(the NULL is the default value that is displayed on the page) this will produce the error
If I enter:
emily 06/01/1900 NULL
this will not produce the error because there is not an emily with that birthdate in the system and the record will be added
If I enter:
greg 11/01/1900 los angeles
***this will work
I made sure to capitalize the word NULL in both the default value on the visual editor add page and in the before record added event:
dim rsname,rsdob,rsSchoolCode

set dal_table=dal.Table("Client_Table")
set rsname = dal_table.Query("name='" & values("name") & "' and dob='" & values("dob") & "'","")
if not rsname.eof and values("location") = "NULL" then

Flush_output

Response.Write "<script>alert('Yikes! - This record address already exists. Please check your spelling/entry.')</script>"
beforeadd = false

else

BeforeAdd = true

end if

Hi Greg, Thanks a million for all your help on this, I realisied the error I made here, I was trying to validate against a field in the table that was not on the add page hence the DAL could not find the field to validate it.
Thanks once again..

Mark.