Are you looking for the SQL syntax or which function to use in LabSQL? The syntax is:
UPDATE table_name [options] SET col_name = expr,... [WHERE clause]
as in UPDATE testres SET meas2 = 2.5 WHERE meas1 < 0
The function in LabSQL to use is SQL Execute. Set the Return Data input to false. You would first use ADO Connection Create and ADO Connection Open.