The IsolationLevels property is a bit mask, that indicates the level of transaction support.
Applies to objects: Connection, Database.
[[Let] RetVal = ] object.IsolationLevels |
The Transactions property syntax has these parts:
Part | Description |
object | Required. A reference to an instance of the object. |
RetVal | Optional. A Long type variable. |
The following situations may occur when using transactions:
Dirty Read. Transaction 1 changes a row. Transaction 2 reads the changed
row before transaction 1 commits the change. If transaction 1 rolls back the
change, transaction 2 will have read a row that is considered to have never
existed.
Nonrepeatable Read. Transaction 1 reads a row. Transaction 2 updates
or deletes that row and commits this change. If transaction 1 attempts to reread
the row, it will receive different row values or discover that the row has been
deleted.
Phantom. Transaction 1 reads a set of rows that satisfy some search criteria.
Transaction 2 generates one or more rows (through either inserts or updates)
that match the search criteria. If transaction 1 reexecutes the statement that
reads the rows, it receives a different set of rows.
The IsolationLevels property may contain a combination of the following
values:
cdbTransReadUncommited - Dirty reads, nonrepeatable reads, and phantoms are possible.
cdbTransReadCommited - Dirty reads are not possible. Nonrepeatable reads and phantoms are
possible.
cdbTransRepeatableRead - Dirty reads and nonrepeatable reads are not possible. Phantoms are
possible.
cdbTransSerializable - Transactions are serializable. Serializable transactions do not allow
dirty reads, nonrepeatable reads, or phantoms.
If equal to 0 - transactions are not supported.
This property is Read-Only.
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See Also |
Connection Object, Database Object, Transactions Property, BeginTrans Method. |