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20 lip 2009 · You can do this via the information_schema tables. For example: SELECT tc.table_schema, tc.constraint_name, tc.table_name, kcu.column_name, ccu.table_schema AS foreign_table_schema, ccu.table_name AS foreign_table_name, ccu.column_name AS foreign_column_name FROM information_schema.table_constraints AS tc JOIN information_schema.key_column ...
In PostgreSQL, a foreign key is a column or a group of columns in a table that uniquely identifies a row in another table. A foreign key establishes a link between the data in two tables by referencing the primary key or a unique constraint of the referenced table.
19 sie 2024 · Learn how to find the foreign keys in a table in MySQL, PostgreSQL, and SQL Server.
The FOREIGN KEY constraint is used to prevent actions that would destroy links between tables. A FOREIGN KEY is a field (or collection of fields) in one table, that refers to the PRIMARY KEY in another table.
9 paź 2024 · In PostgreSQL, we can define a foreign key when creating a table or after a table has been created. Foreign keys reference the primary key of another table and they ensure that the data in the child table matches one of the values in the parent table. Syntax for Foreign Key: CREATE TABLE child_table (column1 datatype, column2 datatype,...
20 sty 2010 · I tried to create a foreign key on one of my tables, referencing a column of a table in a different schema. Something like that: ALTER TABLE my_schema.my_table ADD ( CONSTRAINT my_fk FOREIGN KEY (my_id) REFERENCES other_schema.other_table(other_id) )
The FOREIGN KEY constraint is a key used to link two tables together. A FOREIGN KEY is a field (or collection of fields) in one table that refers to the PRIMARY KEY in another table. The following SQL creates a FOREIGN KEY on the "PersonID" column when the "Orders" table is created:
