Data Access Worldwide Knowledge Base
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QUESTION:
What is the difference between the DataDictionary Read and Find messages?
ANSWER:
The read and find messages are different. They perform an identical find and will return FOUND the same way. The difference is the effect they have on the DD.
The read messages do not change anything in the DD. The DD does not latch on to the new record. CurrentRowId (current_record) and the buffer values do not change. So you use the read messages when you want to find a record using DD finding logic (constraints, custom relates, etc) but you do not want the DD to get changed. For example: a dbGrid needs to find a record for each row but it only updates the DD one time with the current record. So the grid uses reads to fill itself and uses find to latch on to the current record.
The find messages are:
find, request_find, findByrowId, find_by_recnum
The read messagas are:
Request_read, ReadByrowId, Read_by_recnum, locate_next
Request_Assign can be used to take a record that was "read" and latch it to a DDO.
NOTE:
Next_Record should only be used when the direction has been established usually with first_record or last_record.
Contributed By:
John Tuohy
Company: Data Access Worldwide
Web Site: http://www.dataaccess.com
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