Are there any SQL Validators that can check syntax against multiple database servers?
For example, I might want to check whether a particular query will work against
This is an online mysql syntax checker, but this is mysql only http://www.piliapp.com/mysql-syntax-check/
I'm not aware of any that are that specific, these will check that the statements are valid ansi 92/99/2003...
http://developer.mimer.com/validator/index.htm
That will get you 99% of the way there (especially if are only doing CRUD operations)
maybe if you know which reserved words are used by which database you could roll your own simple checker.. see : How to find if a column name is a reserved keyword across various databases
(as already mentioned) If your goal is to create a database agnostic system think about using a third party tool e.g: entityspaces
For the MySQL: try automatic SQL syntax check feature in dbForge Studio for MySQL.
For the Oracle: PL/SQL Editor in dbForge Studio for Oracle
From SQL Server point of view, instead of checking sql syntax against multiple database server you could check syntax "for compliance with the FIPS 127-2 standard. This is based on the ISO standard.".
Example:
SET FIPS_FLAGGER 'INTERMEDIATE'