javax.sql and java.sql
java.sql
Interface Connection
public interface Connection
extends Wrapper
A connection (session) with a specific database. SQL
statements are executed and results are returned within
the context of a connection.
A Connection object's database is able to provide
information describing its tables, its supported SQL
grammar, its stored procedures, the capabilities of this
connection, and so on. This information is obtained with
the getMetaData method.
Interface Connection
• Note: When configuring a Connection, JDBC
applications should use the appropritate Connection
method such as setAutoCommit or
setTransactionIsolation. Applications should not invoke
SQL commands directly to change the connection's
configuration when there is a JDBC method available. By
default a Connection object is in auto-commit mode,
which means that it automatically commits changes after
executing each statement. If auto-commit mode has
been disabled, the method commit must be called
explicitly in order to commit changes; otherwise,
database changes will not be saved.
Connection property inspector
getCatalog
String getCatalog() throws SQLException
Retrieves this Connection object's current catalog name.
Returns:
the current catalog name or null if there is none
Throws:
SQLException - if a database access error occurs or this method is
called on a closed connection
Interface Connection
setHoldability
void setHoldability(int holdability) throws SQLException
Changes the default holdability of ResultSet objects created using this
Connection object to the given holdability. The default holdability of
ResultSet objects can be be determined by invoking
DatabaseMetaData.getResultSetHoldability().
Parameters:
holdability - a ResultSet holdability constant; one of
ResultSet.HOLD_CURSORS_OVER_COMMIT or
ResultSet.CLOSE_CURSORS_AT_COMMIT
Throws:
SQLException - if a database access occurs, this method is called on
a closed connection, or the given parameter is not a ResultSet
constant indicating holdability
SQLFeatureNotSupportedException - if the given holdability is not
supported
Interface Connection
setReadOnly
void setReadOnly(boolean readOnly) throws SQLException
Puts this connection in read-only mode as a hint to the driver to enable database
optimizations. Note: This method cannot be called during a transaction.
Parameters:
readOnly - true enables read-only mode; false disables it
Throws:
SQLException - if a database access error occurs, this method is called on
a closed connection or this method is called during a transaction
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isReadOnly
boolean isReadOnly() throws SQLException
Retrieves whether this Connection object is in read-only mode.
Returns:
true if this Connection object is read-only; false otherwise
Throws:
SQLException - SQLException if a database access error occurs or this
method is called on a closed connection
Interface Connection
setTransactionIsolation
void setTransactionIsolation(int level) throws SQLException
Attempts to change the transaction isolation level for this Connection
object to the one given. The constants defined in the interface Connection
are the possible transaction isolation levels. Note: If this method is called
during a transaction, the result is implementation-defined.
Parameters:
level - one of the following Connection constants:
Connection.TRANSACTION_READ_UNCOMMITTED,
Connection.TRANSACTION_READ_COMMITTED,
Connection.TRANSACTION_REPEATABLE_READ, or
Connection.TRANSACTION_SERIALIZABLE. (Note that
Connection.TRANSACTION_NONE cannot be used because it
specifies that transactions are not supported.)
Throws:
SQLException - if a database access error occurs, this method is
called on a closed connection or the given parameter is not one of the
Connection constants
Interface Connection
setTypeMap
void setTypeMap(Map<String,Class<?>> map) throws SQLException
Installs the given TypeMap object as the type map for this Connection
object. The type map will be used for the custom mapping of SQL structured
types and distinct types.
Parameters:
map - the java.util.Map object to install as the replacement for this
Connection object's default type map
Throws:
SQLException - if a database access error occurs, this method is called
on a closed connection or the given parameter is not a java.util.Map
object
SQLFeatureNotSupportedException - if the JDBC driver does not
support this method
java.sql
Interface ResultSet
public interface ResultSet
extends Wrapper
• A table of data representing a database result set, which is usually
generated by executing a statement that queries the database.
• A ResultSet object maintains a cursor pointing to its current row of
data. Initially the cursor is positioned before the first row. The next
method moves the cursor to the next row, and because it returns
false when there are no more rows in the ResultSet object, it can be
used in a while loop to iterate through the result set.
• A default ResultSet object is not updatable and has a cursor that
moves forward only. Thus, you can iterate through it only once and
only from the first row to the last row. It is possible to produce
ResultSet objects that are scrollable and/or updatable. The following
code fragment, in which con is a valid Connection object, illustrates
how to make a result set that is scrollable and insensitive to updates
by others, and that is updatable. See ResultSet fields for other
options.
Result Set types
The JDBC 1.0 API provided one result set
type—forward-only. The JDBC 2.1 core
API provides three result set types:
forward-only, scroll-insensitive, and scrollsensitive. As their names suggest, the new
result set types support scrolling, but they
differ in their ability to make changes
visible while they are open.
Result Set types
A scroll-insensitive result set is generally not
sensitive to changes that are made while
it is open. A scroll-insensitive result set provides a
static view of the underlying data it
contains. The membership, order, and column
values of rows in a scroll-insensitive result
set are typically fixed when the result set is
created.
Result Set types
On the other hand, a scroll-sensitive result set is
sensitive to changes that are made
while it is open, and provides a ‘dynamic’ view of
the underlying data. For example,
when using a scroll-sensitive result set, changes in
the underlying column values of
rows are visible. The membership and ordering of
rows in the result set may be fixed—
this is implementation defined.
Examples
• The example below illustrates creation of a
result set that is forward-only and uses
readonly concurrency.
Connection con = DriverManager.getConnection(
"jdbc:my_subprotocol:my_subname");
Statement stmt = con.createStatement();
ResultSet rs = stmt.executeQuery(
"SELECT emp_no, salary FROM employees");
Examples
• The next example creates a scrollable result set that is updatable
and sensitive to updates.
• Rows of data are requested to be fetched twenty-five at-a-time from
the database.
Connection con = DriverManager.getConnection(
"jdbc:my_subprotocol:my_subname");
Statement stmt = con.createStatement(
ResultSet.TYPE_SCROLL_SENSITIVE,
ResultSet.CONCUR_UPDATABLE);
stmt.setFetchSize(25);
ResultSet rs = stmt.executeQuery(
"SELECT emp_no, salary FROM employees");
Examples
• The example below creates a result set with the same attributes as
the previous example, however, a prepared statement is used to
produce the result set.
• JDBC 2.1 Core API
• Sun Microsystems Inc. 14 October 5, 1999
PreparedStatement pstmt = con.prepareStatement(
"SELECT emp_no, salary FROM employees where emp_no = ?",
ResultSet.TYPE_SCROLL_SENSITIVE,
ResultSet.CONCUR_UPDATABLE);
pstmt.setFetchSize(25);
pstmt.setString(1, "100010");
ResultSet rs = pstmt.executeQuery();
Due to differences in database implementations, the JDBC API does not
specify an exact set of SQL queries which must yield an updatable result
set for JDBC drivers that support updatability. Developers can, however,
generally expect queries which meet the following criteria to produce an
updatable result set:
1. The query references only a single table in the database.
2. The query does not contain any join operations.
3. The query selects the primary key of the table it references. In addition, an
SQL query should also satisfy the conditions listed below if inserts are to
be performed.
4. The query selects all of the non-nullable columns in the underlying table.
5. The query selects all columns that don’t have a default value.
http://minitorn.tlu.ee/~jaagup/kool/java/abiinfo/docs/6/docs/api/java/sql/ResultSet.html
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javax.sql.ConnectionEvent
javax.sql.ConnectionEventListener
javax.sql.ConnectionPoolDataSurce
javax.sql.DataSource
javax.sql.PooledConnection
javax.sql.RowSet
javax.sql.RowSetEvent
javax.sql.RowSetInternal
javax.sql.RowSetListener
javax.sql.RowSetMetaData
javax.sql.RowSetReader
javax.sql.RowSetWriter
javax.sql.XAConnection
javax.sql.XADataSource
javax.sql
Interface PooledConnection
• public interface PooledConnection
• An object that provides hooks for connection pool management. A
PooledConnection object represents a physical connection to a data
source. The connection can be recycled rather than being closed
when an application is finished with it, thus reducing the number of
connections that need to be made.
• An application programmer does not use the PooledConnection
interface directly; rather, it is used by a middle tier infrastructure that
manages the pooling of connections.
• When an application calls the method DataSource.getConnection, it
gets back a Connection object. If connection pooling is being done,
that Connection object is actually a handle to a PooledConnection
object, which is a physical connection.
• The JDBC driver implementing ConnectionPoolDataSource creates
a new PooledConnection object and returns a handle to it.
Interface PooledConnection
• When an application closes a connection, it calls the Connection
method close. When connection pooling is being done, the
connection pool manager is notified because it has registered itself
as a ConnectionEventListener object using the ConnectionPool
method addConnectionEventListener. The connection pool manager
deactivates the handle to the PooledConnection object and returns
the PooledConnection object to the pool of connections so that it
can be used again. Thus, when an application closes its connection,
the underlying physical connection is recycled rather than being
closed.
• The physical connection is not closed until the connection pool
manager calls the PooledConnection method close. This method is
generally called to have an orderly shutdown of the server or if a
fatal error has made the connection unusable.
Interface PooledConnection
Method Summary
void
addConnectionEventListener(ConnectionEventListener listener)
Registers the given event listener so that it will be notified when an event
occurs on this PooledConnection object.
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void
addStatementEventListener(StatementEventListener listener)
Registers a StatementEventListener with this PooledConnection object.
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void
close()
Closes the physical connection that this PooledConnection object
represents.
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Connection
getConnection()
Creates and returns a Connection object that is a handle for the physical
connection that this PooledConnection object represents.
Interface PooledConnection
Method Summary
void
removeConnectionEventListener(ConnectionEventListener listener)
Removes the given event listener from the list of components that will be
notified when an event occurs on this PooledConnection object.
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void
removeStatementEventListener(StatementEventListener listener)
Removes the specified StatementEventListener from the list of components
that will be notified when the driver detects that a PreparedStatement has been
closed or is invalid.