How do you solve There is no unique constraint matching given keys for referenced table?
- First find out the primary key constraints by typing this code \d table_name. you are shown like this at bottom “some_constraint” PRIMARY KEY, btree (column)
- Drop the constraint: ALTER TABLE table_name DROP CONSTRAINT some_constraint.
What is PRIMARY KEY constraint?
A primary key constraint depicts a key comprising one or more columns that will help uniquely identify every tuple/record in a table. Properties : No duplicate values are allowed, i.e. Column assigned as primary key should have UNIQUE values only. No new row can be inserted with the already existing primary key.
Is there a unique constraint matching given keys?
I tried to create tables using postgresql with these codes, but it’s keep saying that there is no unique constraint matching given keys for referenced table. This message comes up when I tried to create table teaches, section, and evaluation.
Is there a unique constraint for instructor name?
Replacing the single primary key on both fields with a primary key on the id, and a unique key on instructor name would allow you to make sure both fields are unique, while providing the constraint that the teaches table needs to link back to instructors.
Can a primary key be referenced by two columns?
If the primary key is definitely supposed to be two columns, that means it can only be referenced by a foreign key that has both columns: REFERENCES (col1, col2) Thanks for contributing an answer to Stack Overflow!
When to use a foreign key of reference?
A foreign key of REFERENCES (col1) requires that the table have on it a constraint that is one of: If the primary key is definitely supposed to be two columns, that means it can only be referenced by a foreign key that has both columns: REFERENCES (col1, col2)