mysql - SQL foreign key restraint referencing information_schema -

is possible "constrain" columns in 1 table "reference" columns views in information_schema in way (it needn't proper foreign key constraint, hence scare quotes)?-- need minimally-intrusive way of adding arbitrary metadata existing column data (e.g. add "comments" e.g. value shop.cheeses.name shop.cheeses.id =n), , thought of defining table such:

create table shop.metadata (     `table_schema` varchar(64) not null,     `table_name` varchar(64) not null,     `column_name` varchar(64) not null,     `record_id` int(11) unsigned not null,     `comments` text not null, /* show purpose of table */     primary key (`table_schema`, `table_name`, `column_name`, `record_id`),     foreign key (`table_schema`, `table_name`, `column_name`) references information_schema.tables(`table_schema`, `table_name`, `column_name`) ); 

however, statement returns error 1215 (hy000): cannot add foreign key constraint, presumably because table_schema, table_name , column_name not defined unique (edit: if columns unique, seems wouldn't possible because can't reference views in foreign key constraints).

still, there no other way define requirement

• shop.metadata.table_schema must contain extant value information_schema.tables.table_schema
• shop.metadata.table_name must contain extant value information_schema.tables.table_name
• shop.metadata.column_namemust contain extant value information_schema.tables.column_name
• any quadruple of (table_schema, table_name, column_name, record_id) unique?

thanks help.