Other Library Functions

function

dbTableUpdate

Library: omdb - high level database access Include: omdb.xin

Declaration

  define external function dbTableUpdate
             value      dbTable     table
    from   read-only     stream   values
    null    value           stream    null       optional
    where value           stream  where optional

Where:
table

A database table.

values

A stream shelf containing the columns and values to update.

null

An optional string to represent a NULL value rather than the default unattached stream.

where

An optional condition used in the SQL statement to limit the numbers of rows updated.

Purpose

This function updates records in a table using the supplied data and criteria. A NULL data value may be represented as an unattached stream or as an optionally defined string. The column name is identified as the key of each "values" parameter shelf item.

Date and time fields

If the record has a date, time, or timestamp field, you must represent the field's value in the OmniMark Date and Time library format. (This format returns the time with a time zone offset from UTC time, which most databases do not provide.)

The following program shows how to retrieve the average for each enrolled student and use dbTableUpdate to update his or her current average. The field data is updated through the dbTable OMX component.

  process

      ;  local variables
      local dbDatabase this-db
      local dbField student-average variable
      local dbTable student
      local stream SQL-query initial
      {  "select sid, ave(Grade) " ||
          "from StudentCourse " ||
          "group by sid "
      }
      local stream average variable initial { ' ' with key 'Average' }

      ;  create the database OMX objects
      set this-db to dbOpenODBC 'dbDemo'
      dbQuery this-db sql SQL-query record student-average
      set student to dbTableOpen this-db table 'Student'

      ;  retrieve all student course averages
      repeat
          ; exit the loop if no more data exists
          exit unless dbRecordExists student-average

          ;  update the student average
          set average{'Average'} to
                  dbFieldValue student-average[2] null '0'
          dbTableUpdate student from average where
                  "sid = ' " ||  dbFieldValue student-average{'sid'}  ||  " ' "

          ;  advance the cursor
          dbRecordMove student-average
      again

      ;  catch the database exceptions
      catch #external-exception identity catch-id message catch-msg
          output 'An error occurred while accessing an omDB function.%n'
          output '%g(catch-id)  :  %g(catch-msg)%n'

Other Library Functions    dbClose    dbExecute    dbFieldValue    dbIsVersionCompatible    dbLibraryVersion    dbOpenODBC    dbQuery    dbRecordExists    dbRecordMove    dbTableClose    dbTableDelete    dbTableInsert    dbTableOpen    dbTableUpdate

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