Was implementing the MSSQL when I discovered that:

- inserting records using placeholders AND
- retrieving the last id with Insert_ID()

are completely broken!!

Explanation from: http://docs.moodle.org/en/Development:dmllib_2.0_problems

Problem: Queries using placeholders under MSSQL are executed by one sp_executesql() procedure call. In MSSQL procedures, triggers are executed into new scopes (like "shells"), so the Insert_ID() function (internally usind SCOPE_IDENTITY()) doesn't work at all, because the insert has been executed in another scope.

Solution: Patch ADOdb driver so, each time one INSERT is going to be executed by sp_executesql(), we'll add one SCOPE_IDENTITY() in the same procedure execution (that way, both the insert and the identity will be in the same scope). Once executed, return the value of the identity by the standard Insert_ID() function. BC compatible 100% with current code if implemented that way.