Question

Is there a manner to add something like a where clause as a ‘global’ parameter for a mysql session.

For example an company has multiple user and you want to query for the user in this company, normally you would use a statement like:

SELECT * FROM users WHERE users.companyId = 2;

The issue is that adding the WHERE clauses would mean a huge impact on the code. Though, we defined the relations and thus I image (though, I don’t think it exists), that you could create a session with the “global” constrained that all queries in that session should comply to.

Answer 1

You can create a view

CREATE VIEW view2 AS SELECT * FROM table1 WHERE companyid = 2;

If slowness is your curse, there are a few things you can do:

• put an index on the where field(s) in this case companyid.
• if you need more speed you can partition the table by companyid.
• make the table a memory table, and use hash indexes for = and IN fields.
• use InnoDB, instead of MyISAM. InnoDB has faster indexes.
• Do not use select *, explicitly select only the fields you need.

See: http://dev.mysql.com/doc/refman/5.0/en/create-view.html
http://dev.mysql.com/doc/refman/5.5/en/index-btree-hash.html
http://dev.mysql.com/doc/refman/5.0/en/memory-storage-engine.html
http://dev.mysql.com/doc/refman/5.1/en/partitioning.html