SqlParser should parse MySQL DATETIME type

MySQL has two different data types: TIMESTAMP and DATETIME. The difference between them is the range they support.

From the documentation [1]
The TIMESTAMP data type is used for values that contain both date and time parts. TIMESTAMP has a range of '1970-01-01 00:00:01' UTC to '2038-01-19 03:14:07' UTC.

The DATETIME type is used for values that contain both date and time parts. MySQL retrieves and displays DATETIME values in 'YYYY-MM-DD hh:mm:ss' format. The supported range is '1000-01-01 00:00:00' to '9999-12-31 23:59:59'.

Calcite's TIMESTAMP likely supports both ranges, and for unparse logic, the MySQL dialect class always uses DATETIME because the TIMESTAMP range is a subset of the DATETIME range.

The only missing part is parsing the DATETIME datatype. For example

SELECT CAST(timestamp_field AS DATETIME) FROM <table>

[1] https://dev.mysql.com/doc/refman/8.4/en/datetime.html