ALTER TABLE {{.SchemaName}}.{{.TableName}}
  DROP CONSTRAINT IF EXISTS {{.ConstraintName}};

ALTER TABLE {{.SchemaName}}.{{.TableName}}
  ADD CONSTRAINT {{.ConstraintName}}
  FOREIGN KEY ({{.SourceColumns}})
  REFERENCES {{.TargetSchema}}.{{.TargetTable}} ({{.TargetColumns}})
  ON DELETE {{.OnDelete}}
  ON UPDATE {{.OnUpdate}}
  DEFERRABLE;