Need to add more unit tests for various field types

Need to add more unit tests for various field types which would include the following:
 - Error Conditions for conversion.
 - Test max value boundary conditions for INT and BIGINT
 - Check that all identifiers are valid UTF8
 - make sure we have tests for all the several ways that a TIMESTAMP is used for create table
 - DATETIME - check current test coverage
 - TIMEZONES - check current test coverage
 - ENUM
    check test Coverage of not NULL condition
    KeyType
    Limit of range
    check sorting test coverage