ColumnsToString converts a column to a string.

NewRangePair creates a new RangePair.

RangePairsToString converts a ranges pair to a string.

Max -> -2 = -1 - 1 = MaxUint64 - 1.

Min -> -3 = -1 - 2 = MaxUint64 - 2.

Column represents a column in a table, consisting of a column name and a column value.

DateTime from db will be recognize as local timezone, datetime send to server will ignore the timezone.

Extremum to represent the minimum and maximum values of the key.

TimeStamp store in UTC timezone, show in Local timezone.