The ALTER TABLE statement conflicted with the FOREIGN KEY constraint

Question

It occurred because you tried to create a foreign key from tblDomare.PersNR to tblBana.BanNR but/and the values in tblDomare.PersNR didn't match with any of the values in tblBana.BanNR. You cannot create a relation which violates referential integrity.

This query was very useful for me. It shows all values that don't have any matches

select FK_column from FK_table
WHERE FK_column NOT IN
(SELECT PK_column from PK_table)

Try this solution:

There is a data item in your table whose associated value doesn't exist in the table you want to use it as a primary key table. Make your table empty or add the associated value to the second table.

It is possible to create the foreign key using ALTER TABLE tablename WITH NOCHECK ..., which will allow data that violates the foreign key.

"ALTER TABLE tablename WITH NOCHECK ..." option to add the FK -- This solution worked for me.

I guess, a column value in a foreign key table should match with the column value of the primary key table. If we are trying to create a foreign key constraint between two tables where the value inside one column(going to be the foreign key) is different from the column value of the primary key table then it will throw the message.

So it is always recommended to insert only those values in the Foreign key column which are present in the Primary key table column.

For ex. If the Primary table column has values 1, 2, 3 and in Foreign key column the values inserted are different, then the query would not be executed as it expects the values to be between 1 & 3.