There are two ways to control transactions through Sybase Open Client Client-Library:

• setting isolation levels

• using transaction control methods

These techniques are described in the following sections.

2.11.1 Setting Isolation Levels

Table 5: Setting the isolation level

The current isolation level can be determined by calling the function RWDBConnection::isolation() without an argument.

2.11.2 Using Transaction Control Methods

You can explicitly control transactions through the following methods:

RWDBConnection::beginTransaction(const RWCString& name = RWCString()) RWDBConnection::rollbackTransaction(const RWCString& name = RWCString()) RWDBConnection::commitTransaction(const RWCString& name = RWCString()) RWDBConnection::setSavepoint(const RWCString& name)

which correspond to:

"begin transaction [name]" "rollback transaction [name]" "commit transaction [name]" "save transaction name"

An application can add the DB Interface Module transaction methods to its code to take explicit control of its transaction blocks. Transactions may be nested and the savepoint feature is supported. The savepoint feature allows a current transaction to be partially rolled back to a marked point. The following example demonstrates the use of the DB Interface Module savepoint feature and other transaction processing methods.

// Assume we have a table myTable(c int) with no rows in it. RWDBInserter ins = myTable.inserter(); cn.beginTransaction("outmost"); // Begin transaction. // Transaction name is allowed. // Note: unlike savepoint name, // transaction name is not used // by server. (ins << 1).execute(cn); // First insertion cn.beginTransaction("inner"); // Nested transaction begins ... cn.setSavepoint("svp1"); // Save first insertion (ins << 2).execute(cn); // Second insertion (ins << 3).execute(cn); // Third insertion cn.rollbackTransaction("svp1"); // Roll back second and // third insertions. cn.commitTransaction("inner"); // Pairing inner transaction cn.commitTransaction("outmost"); // Commit transaction on // part that is not rolled back. // The above program results in myTable holding one row of data. // Its value is 1.