GRANT ALL PRIVILEGES ON *.* TO ''@'localhost' IDENTIFIED BY 'PASSWORD' WITH GRANT OPTION;
The manual says:
In this case, any user who connects from the local host with the correct password for the anonymous user will be permitted access, with the privileges associated with the anonymous-user account.
So for granting create and alter permissions for MS SQL, the syntax will be:
GRANT ALTER ON dbo TO public;
According to SQL Server 2008 help:
Requires CREATE TABLE permission in the database and ALTER permission on the schema in which the table is being created.
Granting permission to create tables to a specific user in a specific database not only requires CREATE TABLE permissions but also requires ALTER permissions to the schema, e.g. DBO.
GRANT ALTER ON Schema :: DBO TO user_mydatabase
GRANT CREATE TABLE TO user_mydatabase