Transfer process

The following describes the bulk copy and express transfer process.

To initiate the bulk copy and express transfer process

1. The client application initiates a transfer request.

2. The access service receives the transfer request and executes the sourceselectstatement against the source database to retrieve the schema of the result set, including column datatypes, length, precision, and scale.

3. The access service queries the target table for a description of the target table columns and compares this information to the structure of the result set for the following criteria:

   • The target table must have at least as many columns as the result set.

   • The datatype of each result set column must be able to be converted to the datatype of the target column.

   If either of these tests fails, the access service stops processing the transfer and issues an error message.

4. If the transfer statement includes the with replace or truncate clause, the access service deletes data in the target table, provided the user ID of the person executing the request is authorized to do so. If the user ID is not authorized, the transfer fails.

5. The access service maps the columns from the result set to the columns in the target table in the same order. The access service attempts to insert NULL values (if allowable) in all columns in the target table that does not have corresponding columns in the result set.

6. The access service prepares an insert or equivalent bulk load statement for execution against the target table.

7. For bulk copy transfer only, if conversion errors occur as rows are inserted (for example, a value is out of range), the invalid rows are handled according to the values set in the following properties:

   • CharConvertError

   • NumConvertError

   • DatetimeConvertError

   • DefaultDate

   • DefaultTime

   • DefaultNum

   The transfer continues processing. If the SendWarningMessages property is set to yes, the access service sends a warning message to the client application.

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