CONCAT'ing NULL fields

Try

ISNULL(FirstName, '<BlankValue>') -- In SQL Server
IFNULL(Firstname, '<BlankValue>') -- In MySQL

So,

CONCAT(ISNULL(FirstName,''),ISNULL(LastName,''),ISNULL(Email,'')) -- In SQL Server
CONCAT(IFNULL(FirstName,''),IFNULL(LastName,''),IFNULL(Email,'')) -- In MySQL

would return the same thing without the null issue (and a blank string where nulls should be).

Look at CONCAT_WS

For example:

CONCAT_WS('',NULL,"TEST STRING","TEST STRING 2")

Yields

TEST STRINGTEST STRING 2

This is easier than constructing IFNULL around everything. You can use an empty string as the separator.

In mysql isnull wont work some time. try IFNULL(),

CONCAT(IFNULL(FirstName,''),IFNULL(LastName,''),IFNULL(Email,''))