Just a note on units of measurement.

I have previously worked with many laboratory databases and there is always need for a unit conversion look up table for any sort of calculations.

Contents would look like this

SourceUnits ConvertedUnits Multiplier

mg g 0.001

g mg 1000

The use of a standard conversion table like this avoids maintaining multiple calculations elsewhere in the database.

Calculations should be converted to standard units, performed, and then converted to display units, and the very last operation performed should be any rounding if required. Particularly with chemistry or pharmaceuticals this is very important.

The fields in the rest of the database should not contain the values & units in the same column, fields should not contain multiple pieces of data as per best practice, which means you avoid any parsing to strip out units.

Dave