如何在 PostgreSQL 中按名称删除约束？

You need to retrieve the table names by running the following query:

SELECT *
FROM information_schema.constraint_table_usage
WHERE table_name = 'your_table'

Alternatively you can use pg_constraint to retrieve this information

select n.nspname as schema_name,
t.relname as table_name,
c.conname as constraint_name
from pg_constraint c
join pg_class t on c.conrelid = t.oid
join pg_namespace n on t.relnamespace = n.oid
where t.relname = 'your_table_name';

Then you can run the required ALTER TABLE statement:

ALTER TABLE your_table DROP CONSTRAINT constraint_name;

Of course you can make the query return the complete alter statement:

SELECT 'ALTER TABLE '||table_name||' DROP CONSTRAINT '||constraint_name||';'
FROM information_schema.constraint_table_usage
WHERE table_name in ('your_table', 'other_table')

Don't forget to include the table_schema in the WHERE clause (and the ALTER statement) if there are multiple schemas with the same tables.

If your on 9.x of PG you could make use of the DO statement to run this. Just do what a_horse_with_no_name did, but apply it to a DO statement.

DO $$DECLARE r record;
BEGIN
FOR r IN SELECT table_name,constraint_name
FROM information_schema.constraint_table_usage
WHERE table_name IN ('your_table', 'other_table')
LOOP
EXECUTE 'ALTER TABLE ' || quote_ident(r.table_name)|| ' DROP CONSTRAINT '|| quote_ident(r.constraint_name) || ';';
END LOOP;
END$$;

Drop the right foreign key constraint

ALTER TABLE affiliations
DROP CONSTRAINT affiliations_organization_id_fkey;

NOTE:

affiliations -> Table Name


affiliations_organization_id_fkey ->Constraint name

List contraints:

SELECT con.*
FROM pg_catalog.pg_constraint con
INNER JOIN pg_catalog.pg_class     rel ON rel.oid = con.conrelid
INNER JOIN pg_catalog.pg_namespace nsp ON nsp.oid = connamespace
WHERE nsp.nspname = 'your_schema' AND
rel.relname = 'your_table';

Remove the contraint:

ALTER TABLE your_schema.your_table DROP CONSTRAINT the_constraint_name;