UPDATE failed due to key violation VBA SQL Access - sql

Question

I need help with this
I have an MS Access db form which will enable users edit details about a project and the new values entered will be saved to the db table when the save button is clicked I am using the sql UPDATE syntax to do this and my code is similar to below
Private Sub Save_Click()
ltemp = " UPDATE Table1 "
ltemp = ltemp & " SET ClientName = 'ANN' "
ltemp = ltemp & " WHERE ProjectID = 2333 "
CurrentDb.Execute (ltemp)
End Sub
with this code, nothing happened. The code would execute with no errors but the value on the table wouldnt change.
I tried the code
DoCmd.RunSQL " UPDATE Table1 SET ClientName = 'ANN' WHERE ProjectID = 2333"
with this i got a long error message which indicated that the records couldnt be updated due to key violation. The problem is that the field 'ClientName' is not the primary key, although it is linked (in a relationship) to the primary key of another table.
both codes work to update other fields except this one which is in a relationship with the primary key of another table.

Answer 1

Obviously there is no record in your 'client' table with the 'ANN' id, so it cannot be set as a valid value for the corresponding\foreign key field in your updated table.
currentDb.execute instruction will not return any error message (not like the 'DoCommand' one) because it's not supposed to, as long as the syntax is correct (see below). You could try to use the currentDb.RecordsAffected to check if any record was changed by your instruction. Check parameters available for the execute method for further details.
Access Help:
"In a Microsoft Jet workspace, if you provide a syntactically correct SQL statement and have the appropriate permissions, the Execute method won't fail — even if not a single row can be modified or deleted. Therefore, always use the dbFailOnError option when using the Execute method to run an update or delete query. This option generates a run-time error and rolls back all successful changes if any of the records affected are locked and can't be updated or deleted."

Answer 2

You are attempting to violate the referential integrity set up on your database.
As you've noted, there is another table, which will look something like this:
CREATE TABLE Client
(
ClientName VARCHAR(100),
... other client fields here
);
And there is a FOREIGN KEY setup between columns Table1.ClientName and Client.ClientName.
To avoid this, either:
INSERT a client with the name ANN into the other table
DROP the foreign key constraint on Table1.ClientName if you intend to violate the constraint (but note that joins may fail when the client is missing)
Change the design and start using surrogate keys, such as ClientID and referencing the Surrogate key in your other tables (instead of 'natural' keys like Client Name). This way, clients can get married, change their names etc and your database won't break :)