Copies up to count pages between the source and destination databases specified by the buHandle argument. This function is part of the Online Backup Feature for the online backup feature of SQLite.

Arguments: The arguments are:
buHandle [required] The non-null handle to the backup returned from oosqlBackupInit .
count The whole number count of database pages to copy. If count is negative, all of the remaining pages are copied. Ifcountis omitted it defaults to 5.
Return value: Ifcountpages are successfully copied, and there are still more pages to be copied, then OK (.ooSQLite~OK) is returned. IfoosqlBackupStepsuccessfully finishes copying all pages from source to destination, then DONE (.ooSQLite~DONE) is returned. Otherwise an error code is returned. Some errors are fatal and some are not. The remarks section further discusses this.
Remarks: If the database engine can not obtain a required lock thenoosqlBackupStep returns BUSY (.ooSQLite~BUSY.) If the source database connection is being used to write to the source database when oosqlBackupStepis called, then LOCKED is returned. The return code can also be NOMEM, READONLY, or one of the IO_ERR_XXX codes. After BUSY or LOCKED,oosqlBackupStepcan be tried again. But NOMEM, READONLY, and IO_ERR_XXX are considered fatal. There is no point in retrying if any of those codes are returned. The application must accept that the backup operation has failed and call oosqlBackupFinish to release associated resources.
Details The functionality of theoosqlSteproutine is similar to that of the sqlite3_backup_step SQLite API.
Example: This example initializes a backup, copies everything in one step, checks for error, and cleans up:
buObj = oosqlBackupInit(srcConn, dstConn)
if oosqlIsHandleNull(buObj) then do
-- handle error
ret = oosqlBackupStep(buObj, -1)
if ret \\== .ooSQLite~DONE then do
-- back up failed, handle error
ret = oosqlBackupFinish(buObj)
-- Backup okay, we are done with the connections
-- and the backup handle, close everything ...
ret = oosqlBackupFinish(buObj)
ret = oosqlClose(dstConn)
ret = oosqlClose(srcConn)
return 0