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Database Management: Tables - page 23 / 35

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1/23/2015  UT Dallas

POEC 6382 Applied GIS Software

23

Modifying Record (item) Values in a File

UPDATE allows you to change the values of specific records for any item in the currently selected file.  UPDATE first prompts you for the number of the record to update.  The current item values for that record are then listed, followed by an Edit? Prompt.  To change a value, type the name of the item you want to change followed by an “=“ and the new value:

Enter record number: 2    (will list current values for that record)

edit?  soil_type = 30           (or soil_type = ‘clay’ if defined as character)

edit? <return>

Enter Record Number: <return>

CALCULATE assigns new values for a numeric data item for the  currently selected records  (Tables: N, I, F, B, D;  INFO: I, N, D).

enter command>  calculate item_name  =  new_value

enter command>  calculate item_name_2 =  item_name_1 * value

Same functionality as CALCULATE in ArcPlot. Note spaces surrounding   =   sign!!

MOVE  assigns new character data item (C) for selected records

     enter command>  move   ‘new char string’   to   item_name

enter command>   move   item_name_1   to   item_name_2

For the same functionality in ArcPlot use MOVEITEM. (MOVE is very different in ArcPLot!)

PURGE   removes all selected records from a table (but item definitions remain--handy, for example,  if  ADD FROM screws up, and you need to try again). KILL deletes the entire file.

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