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--Be aware: this function won't copy attributes of initial foreign key. | |
--It only takes foreign table name / column name, drops current key and replaces with new one. | |
CREATE OR REPLACE FUNCTION | |
replace_foreign_key(f_table VARCHAR, f_column VARCHAR, new_options VARCHAR) | |
RETURNS VARCHAR | |
AS $$ | |
DECLARE constraint_name varchar; | |
DECLARE reftable varchar; | |
DECLARE refcolumn varchar; | |
BEGIN | |
SELECT tc.constraint_name, ccu.table_name AS foreign_table_name, ccu.column_name AS foreign_column_name | |
FROM | |
information_schema.table_constraints AS tc | |
JOIN information_schema.key_column_usage AS kcu | |
ON tc.constraint_name = kcu.constraint_name | |
JOIN information_schema.constraint_column_usage AS ccu | |
ON ccu.constraint_name = tc.constraint_name | |
WHERE constraint_type = 'FOREIGN KEY' | |
AND tc.table_name= f_table AND kcu.column_name= f_column | |
INTO constraint_name, reftable, refcolumn; | |
EXECUTE 'alter table ' || f_table || ' drop constraint ' || constraint_name || | |
', ADD CONSTRAINT ' || constraint_name || ' FOREIGN KEY (' || f_column || ') ' || | |
' REFERENCES ' || reftable || '(' || refcolumn || ') ' || new_options || ';'; | |
RETURN 'Constraint replaced: ' || constraint_name || ' (' || f_table || '.' || f_column || | |
' -> ' || reftable || '.' || refcolumn || '); New options: ' || new_options; | |
END; | |
$$ LANGUAGE plpgsql; | |
--https://stackoverflow.com/a/32920837 | |
--credits to Dan Key |
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