fixes #240

manual/docs/Transactions - Isolation levels.php

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+<?php  ?>
+A transaction isolation level sets the default transactional behaviour.
+As the name 'isolation level' suggests, the setting determines how isolated each transation is,
+or what kind of locks are associated with queries inside a transaction.
+The four availible levels are (in ascending order of strictness):
+<br \><br \>
+<i>READ UNCOMMITTED</i>:  Barely transactional, this setting allows for so-called 'dirty reads',
+where queries inside one transaction are affected by uncommitted changes in another transaction.
+<br \><br \>
+<i>READ COMMITTED</i>: Committed updates are visible within another transaction.
+ This means identical queries within a transaction can return differing results. This is the default in some DBMS's.
+<br \> <br \>
+<i>REPEATABLE READ</i>: Within a transaction, all reads are consistent. This is the default of Mysql INNODB engine.
+<br \><br \>
+<i>SERIALIZABLE</i>: Updates are not permitted in other transactions if a transaction has run an ordinary SELECT query.
+<br \><br \>
+<?php
+renderCode("<?php
+\$tx = \$conn->transaction; // get the transaction module
+
+// sets the isolation level to READ COMMITTED
+\$tx->setIsolation('READ COMMITTED');
+
+// sets the isolation level to SERIALIZABLE
+\$tx->setIsolation('SERIALIZABLE');
+
+// Some drivers (like Mysql) support the fetching of current transaction
+// isolation level. It can be done as follows:
+\$level = \$tx->getIsolation();
+?>");
+?>

manual/docs/Transactions - Savepoints.php

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+<?php ?>
+Doctrine supports transaction savepoints. This means you can set named transactions and have them nested.
+<br \><br \>
+The Doctrine_Transaction::beginTransaction(<i>$savepoint</i>) sets a named transaction savepoint with a name of <i>$savepoint</i>.
+If the current transaction has a savepoint with the same name, the old savepoint is deleted and a new one is set.
+<br \><br \>
+<?php
+renderCode("<?php
+try {
+    \$conn->beginTransaction();
+    // do some operations here
+
+    // creates a new savepoint called mysavepoint
+    \$conn->beginTransaction('mysavepoint');
+    try {
+        // do some operations here
+
+        \$conn->commit('mysavepoint');
+    } catch(Exception \$e) {
+        \$conn->rollback('mysavepoint');
+    }
+    \$conn->commit();
+} catch(Exception \$e) {
+    \$conn->rollback();
+}
+?>");
+?>
+
+<br \><br \>
+The Doctrine_Transaction::rollback(<i>$savepoint</i>) rolls back a transaction to the named savepoint.
+Modifications that the current transaction made to rows after the savepoint was set are undone in the rollback.
+
+NOTE: Mysql, for example, does not release the row locks that were stored in memory after the savepoint.
+<br \><br \>
+Savepoints that were set at a later time than the named savepoint are deleted.
+<br \><br \>
+The Doctrine_Transaction::commit(<i>$savepoint</i>) removes the named savepoint from the set of savepoints of the current transaction. 
+<br \><br \>
+All savepoints of the current transaction are deleted if you execute a commit or rollback is being called without savepoint name parameter.
+<?php
+renderCode("<?php
+try {
+    \$conn->beginTransaction();
+    // do some operations here
+
+    // creates a new savepoint called mysavepoint
+    \$conn->beginTransaction('mysavepoint');
+    
+    // do some operations here
+
+    \$conn->commit();  // deletes all savepoints
+} catch(Exception \$e) {
+    \$conn->rollback(); // deletes all savepoints
+}
+?>");
+?>