Specifying Access Mode
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The access mode parameter describes the actions a transaction can perform against a table. The default access mode, isc_tpb_write, enables a transaction to read data from a table and write data to it. A second access mode, isc_tpb_read, restricts table access to read only. For example, the following TPB declaration specifies a read-only transaction:
static char isc_tpb[] = {isc_tpb_version3, isc_tpb_read};
A TPB should specify only one access mode parameter. If more than one is specified, later declarations override earlier ones.
If a TPB is declared that omits the access mode parameter, InterBase interprets transaction access as read and write.