You must have a grammatical error

For example: field = col1, fieldvalues=relust.

Then your final splicing result is insert into water_info ( col1,) values(relust,)

Note that there is an extra "comma" after the last splicing above

So you can process the field and fieldvalues ??after the loop execution is completed

The simplest processing is

field=field.remove(field.length-1, 1) and

fieldvalue=fieldvalue.remove(fieldvalues.length-1, 1)

Remove the last ",".