#3780
#3780 Referencing column 'userid' and referenced column 'userid' in foreign key constraint
The error message "#3780 Referencing column 'userid' and referenced column 'userid' in foreign key constraint" typically occurs in database management systems like MySQL or MariaDB when trying to create a foreign key constraint that references a column in another table with the same name.
This error can be resolved by specifying a different name for either the referencing column or the referenced column. Here's how you can fix it:
Option 1 - Rename Referencing Column:
If the referencing column and the referenced column have the same name (e.g., 'userid'), you can rename the referencing column to avoid the conflict. For example:
sql
ALTER TABLE your_table
CHANGE COLUMN userid user_id INT(11),
ADD CONSTRAINT fk_userid
FOREIGN KEY (user_id)
REFERENCES other_table(userid);
In this example, we changed the name of the referencing column from 'userid' to 'user_id' and added the foreign key constraint.
Option 2 - Rename Referenced Column:
Alternatively, if the referenced column and the referencing column have the same name, you can rename the referenced column in the other table. For example:
sql
ALTER TABLE other_table
CHANGE COLUMN userid user_id INT(11);
Make sure to update any references to this column in other parts of your database schema and application code.
Option 3 - Use Different Column Names:
If renaming either the referencing column or the referenced column is not feasible, you can use different column names for the foreign key constraint. For example:
sql
ALTER TABLE your_table
ADD COLUMN user_ref_id INT(11),
ADD CONSTRAINT fk_user_ref_id
FOREIGN KEY (user_ref_id)
REFERENCES other_table(userid);
In this case, we added a new column 'user_ref_id' to 'your_table' and created the foreign key constraint using this new column.
Remember to adjust the SQL statements based on your specific table and column names. Also, ensure that the data types and lengths of the columns match in both the referencing and referenced tables to avoid any additional errors.
