Hi, I was looking at the CREATE TABLE syntax and I saw this reference definition for InnoDB tables:
reference_definition: REFERENCES tbl_name [(index_col_name,...)] [MATCH FULL | MATCH PARTIAL | MATCH SIMPLE] [ON DELETE reference_option] [ON UPDATE reference_option] reference_option: RESTRICT | CASCADE | SET NULL | NO ACTION Well, I pretty undestood all but I can't understand 2 things about MATCH option: 1. Which of three options (SIMPLE, FULL, PARTIAL) are implemented in the current production version of MySQL? Reading around, I think SIMPLE and FULL are supported. What about PARTIAL? Is it supported? 2. About MATCH PARTIAL. I could not find a good explanation on how it works. I found here http://forge.mysql.com/wiki/ForeignKeySupport the explanations on MATCH SIMPLE and MATCH FULL: --------------QUOTED------------- Handling of the the MATCH clause -- The HLS specifies that support for MATCH SIMPLE only is required. Since it is very easy to support MATCH FULL if we already have support for MATCH SIMPLE, MATCH FULL should perhaps be added to the list of requirements as an optional feature. These types of the MATCH clause differ only in case of checks that are done during insertion into a referencing table. So they can be implemented by a simple check which is to be done at the beggining of the trigger which is responsible for processing of a foreign key check on insertion: * if the match type is SIMPLE and one or more foreign key columns in the row being inserted is NULL, then regard the constraint as satisified. Otherwise continue with checking. * if the match type for the foreign key constraint is FULL and all foreign key columns in the row being inserted are NULL, then treat the constraint as satisified. If at least one of columns in the foreign key is NULL, and at least one of them is not NULL, treat the foreign key constraint as failed. Otherwise (if all columns in the foreign key are not NULL), continue with checking. Handling of foreign key constraints with MATCH PARTIAL is more complex and support for it is not required in the HLS. ------------END QUOTED------------- But there's no explanation about MATCH PARTIAL. So, what about MATCH PARTIAL. Is it supported and how does it works? Thanks for any infos. Giorgio -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
