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Standard Ed. 6
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java.sql
Interface Connection

All Superinterfaces:
Wrapper
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.

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.

A new Connection object created using the JDBC 2.1 core API has an initially empty type map associated with it. A user may enter a custom mapping for a UDT in this type map. When a UDT is retrieved from a data source with the method ResultSet.getObject, the getObject method will check the connection's type map to see if there is an entry for that UDT. If so, the getObject method will map the UDT to the class indicated. If there is no entry, the UDT will be mapped using the standard mapping.

A user may create a new type map, which is a java.util.Map object, make an entry in it, and pass it to the java.sql methods that can perform custom mapping. In this case, the method will use the given type map instead of the one associated with the connection.

For example, the following code fragment specifies that the SQL type ATHLETES will be mapped to the class Athletes in the Java programming language. The code fragment retrieves the type map for the Connection object con, inserts the entry into it, and then sets the type map with the new entry as the connection's type map.

      java.util.Map map = con.getTypeMap();
      map.put("mySchemaName.ATHLETES", Class.forName("Athletes"));
      con.setTypeMap(map);
See Also:
DriverManager.getConnection(java.lang.String, java.util.Properties), Statement, ResultSet, DatabaseMetaData

Field Summary
static int TRANSACTION_NONE
          A constant indicating that transactions are not supported.
static int TRANSACTION_READ_COMMITTED
          A constant indicating that dirty reads are prevented; non-repeatable reads and phantom reads can occur.
static int TRANSACTION_READ_UNCOMMITTED
          A constant indicating that dirty reads, non-repeatable reads and phantom reads can occur.
static int TRANSACTION_REPEATABLE_READ
          A constant indicating that dirty reads and non-repeatable reads are prevented; phantom reads can occur.
static int TRANSACTION_SERIALIZABLE
          A constant indicating that dirty reads, non-repeatable reads and phantom reads are prevented.
 
Method Summary
 void clearWarnings()
          Clears all warnings reported for this Connection object.
 void close()
          Releases this Connection object's database and JDBC resources immediately instead of waiting for them to be automatically released.
 void commit()
          Makes all changes made since the previous commit/rollback permanent and releases any database locks currently held by this Connection object.
 Array createArrayOf(String typeName, Object[] elements)
          Factory method for creating Array objects.
 Blob createBlob()
          Constructs an object that implements the Blob interface.
 Clob createClob()
          Constructs an object that implements the Clob interface.
 NClob createNClob()
          Constructs an object that implements the NClob interface.
 SQLXML createSQLXML()
          Constructs an object that implements the SQLXML interface.
 Statement createStatement()
          Creates a Statement object for sending SQL statements to the database.
 Statement createStatement(int resultSetType, int resultSetConcurrency)
          Creates a Statement object that will generate ResultSet objects with the given type and concurrency.
 Statement createStatement(int resultSetType, int resultSetConcurrency, int resultSetHoldability)
          Creates a Statement object that will generate ResultSet objects with the given type, concurrency, and holdability.
 Struct createStruct(String typeName, Object[] attributes)
          Factory method for creating Struct objects.
 boolean getAutoCommit()
          Retrieves the current auto-commit mode for this Connection object.
 String getCatalog()
          Retrieves this Connection object's current catalog name.
 Properties getClientInfo()
          Returns a list containing the name and current value of each client info property supported by the driver.
 String getClientInfo(String name)
          Returns the value of the client info property specified by name.
 int getHoldability()
          Retrieves the current holdability of ResultSet objects created using this Connection object.
 DatabaseMetaData getMetaData()
          Retrieves a DatabaseMetaData object that contains metadata about the database to which this Connection object represents a connection.
 int getTransactionIsolation()
          Retrieves this Connection object's current transaction isolation level.
 Map<String,Class<?>> getTypeMap()
          Retrieves the Map object associated with this Connection object.
 SQLWarning getWarnings()
          Retrieves the first warning reported by calls on this Connection object.
 boolean isClosed()
          Retrieves whether this Connection object has been closed.
 boolean isReadOnly()
          Retrieves whether this Connection object is in read-only mode.
 boolean isValid(int timeout)
          Returns true if the connection has not been closed and is still valid.
 String nativeSQL(String sql)
          Converts the given SQL statement into the system's native SQL grammar.
 CallableStatement prepareCall(String sql)
          Creates a CallableStatement object for calling database stored procedures.
 CallableStatement prepareCall(String sql, int resultSetType, int resultSetConcurrency)
          Creates a CallableStatement object that will generate ResultSet objects with the given type and concurrency.
 CallableStatement prepareCall(String sql, int resultSetType, int resultSetConcurrency, int resultSetHoldability)
          Creates a CallableStatement object that will generate ResultSet objects with the given type and concurrency.
 PreparedStatement prepareStatement(String sql)
          Creates a PreparedStatement object for sending parameterized SQL statements to the database.
 PreparedStatement prepareStatement(String sql, int autoGeneratedKeys)
          Creates a default PreparedStatement object that has the capability to retrieve auto-generated keys.
 PreparedStatement prepareStatement(String sql, int[] columnIndexes)
          Creates a default PreparedStatement object capable of returning the auto-generated keys designated by the given array.
 PreparedStatement prepareStatement(String sql, int resultSetType, int resultSetConcurrency)
          Creates a PreparedStatement object that will generate ResultSet objects with the given type and concurrency.
 PreparedStatement prepareStatement(String sql, int resultSetType, int resultSetConcurrency, int resultSetHoldability)
          Creates a PreparedStatement object that will generate ResultSet objects with the given type, concurrency, and holdability.
 PreparedStatement prepareStatement(String sql, String[] columnNames)
          Creates a default PreparedStatement object capable of returning the auto-generated keys designated by the given array.
 void releaseSavepoint(Savepoint savepoint)
          Removes the specified Savepoint and subsequent Savepoint objects from the current transaction.
 void rollback()
          Undoes all changes made in the current transaction and releases any database locks currently held by this Connection object.
 void rollback(Savepoint savepoint)
          Undoes all changes made after the given Savepoint object was set.
 void setAutoCommit(boolean autoCommit)
          Sets this connection's auto-commit mode to the given state.
 void setCatalog(String catalog)
          Sets the given catalog name in order to select a subspace of this Connection object's database in which to work.
 void setClientInfo(Properties properties)
          Sets the value of the connection's client info properties.
 void setClientInfo(String name, String value)
          Sets the value of the client info property specified by name to the value specified by value.
 void setHoldability(int holdability)
          Changes the default holdability of ResultSet objects created using this Connection object to the given holdability.
 void setReadOnly(boolean readOnly)
          Puts this connection in read-only mode as a hint to the driver to enable database optimizations.
 Savepoint setSavepoint()
          Creates an unnamed savepoint in the current transaction and returns the new Savepoint object that represents it.
 Savepoint setSavepoint(String name)
          Creates a savepoint with the given name in the current transaction and returns the new Savepoint object that represents it.
 void setTransactionIsolation(int level)
          Attempts to change the transaction isolation level for this Connection object to the one given.
 void setTypeMap(Map<String,Class<?>> map)
          Installs the given TypeMap object as the type map for this Connection object.
 
Methods inherited from interface java.sql.Wrapper
isWrapperFor, unwrap
 

Field Detail

TRANSACTION_NONE

static final int TRANSACTION_NONE
A constant indicating that transactions are not supported.
See Also:
Constant Field Values

TRANSACTION_READ_UNCOMMITTED

static final int TRANSACTION_READ_UNCOMMITTED
A constant indicating that dirty reads, non-repeatable reads and phantom reads can occur. This level allows a row changed by one transaction to be read by another transaction before any changes in that row have been committed (a "dirty read"). If any of the changes are rolled back, the second transaction will have retrieved an invalid row.
See Also:
Constant Field Values

TRANSACTION_READ_COMMITTED

static final int TRANSACTION_READ_COMMITTED
A constant indicating that dirty reads are prevented; non-repeatable reads and phantom reads can occur. This level only prohibits a transaction from reading a row with uncommitted changes in it.
See Also:
Constant Field Values

TRANSACTION_REPEATABLE_READ

static final int TRANSACTION_REPEATABLE_READ
A constant indicating that dirty reads and non-repeatable reads are prevented; phantom reads can occur. This level prohibits a transaction from reading a row with uncommitted changes in it, and it also prohibits the situation where one transaction reads a row, a second transaction alters the row, and the first transaction rereads the row, getting different values the second time (a "non-repeatable read").
See Also:
Constant Field Values

TRANSACTION_SERIALIZABLE

static final int TRANSACTION_SERIALIZABLE
A constant indicating that dirty reads, non-repeatable reads and phantom reads are prevented. This level includes the prohibitions in TRANSACTION_REPEATABLE_READ and further prohibits the situation where one transaction reads all rows that satisfy a WHERE condition, a second transaction inserts a row that satisfies that WHERE condition, and the first transaction rereads for the same condition, retrieving the additional "phantom" row in the second read.
See Also:
Constant Field Values
Method Detail

createStatement

Statement createStatement()
                          throws SQLException
Creates a Statement object for sending SQL statements to the database. SQL statements without parameters are normally executed using Statement objects. If the same SQL statement is executed many times, it may be more efficient to use a PreparedStatement object.

Result sets created using the returned Statement object will by default be type TYPE_FORWARD_ONLY and have a concurrency level of CONCUR_READ_ONLY. The holdability of the created result sets can be determined by calling getHoldability().

Returns:
a new default Statement object
Throws:
SQLException - if a database access error occurs or this method is called on a closed connection

prepareStatement

PreparedStatement prepareStatement(String sql)
                                   throws SQLException
Creates a PreparedStatement object for sending parameterized SQL statements to the database.

A SQL statement with or without IN parameters can be pre-compiled and stored in a PreparedStatement object. This object can then be used to efficiently execute this statement multiple times.

Note: This method is optimized for handling parametric SQL statements that benefit from precompilation. If the driver supports precompilation, the method prepareStatement will send the statement to the database for precompilation. Some drivers may not support precompilation. In this case, the statement may not be sent to the database until the PreparedStatement object is executed. This has no direct effect on users; however, it does affect which methods throw certain SQLException objects.

Result sets created using the returned PreparedStatement object will by default be type TYPE_FORWARD_ONLY and have a concurrency level of CONCUR_READ_ONLY. The holdability of the created result sets can be determined by calling getHoldability().

Parameters:
sql - an SQL statement that may contain one or more '?' IN parameter placeholders
Returns:
a new default PreparedStatement object containing the pre-compiled SQL statement
Throws:
SQLException - if a database access error occurs or this method is called on a closed connection

prepareCall

CallableStatement prepareCall(String sql)
                              throws SQLException
Creates a CallableStatement object for calling database stored procedures. The CallableStatement object provides methods for setting up its IN and OUT parameters, and methods for executing the call to a stored procedure.

Note: This method is optimized for handling stored procedure call statements. Some drivers may send the call statement to the database when the method prepareCall is done; others may wait until the CallableStatement object is executed. This has no direct effect on users; however, it does affect which method throws certain SQLExceptions.

Result sets created using the returned CallableStatement object will by default be type TYPE_FORWARD_ONLY and have a concurrency level of CONCUR_READ_ONLY. The holdability of the created result sets can be determined by calling getHoldability().

Parameters:
sql - an SQL statement that may contain one or more '?' parameter placeholders. Typically this statement is specified using JDBC call escape syntax.
Returns:
a new default CallableStatement object containing the pre-compiled SQL statement
Throws:
SQLException - if a database access error occurs or this method is called on a closed connection

nativeSQL

String nativeSQL(String sql)
                 throws SQLException
Converts the given SQL statement into the system's native SQL grammar. A driver may convert the JDBC SQL grammar into its system's native SQL grammar prior to sending it. This method returns the native form of the statement that the driver would have sent.
Parameters:
sql - an SQL statement that may contain one or more '?' parameter placeholders
Returns:
the native form of this statement
Throws:
SQLException - if a database access error occurs or this method is called on a closed connection

setAutoCommit

void setAutoCommit(boolean autoCommit)
                   throws SQLException
Sets this connection's auto-commit mode to the given state. If a connection is in auto-commit mode, then all its SQL statements will be executed and committed as individual transactions. Otherwise, its SQL statements are grouped into transactions that are terminated by a call to either the method commit or the method rollback. By default, new connections are in auto-commit mode.

The commit occurs when the statement completes. The time when the statement completes depends on the type of SQL Statement:

For DML statements, such as Insert, Update or Delete, and DDL statements, the statement is complete as soon as it has finished executing. For Select statements, the statement is complete when the associated result set is closed. For CallableStatement objects or for statements that return multiple results, the statement is complete when all of the associated result sets have been closed, and all update counts and output parameters have been retrieved.

NOTE: If this method is called during a transaction and the auto-commit mode is changed, the transaction is committed. If setAutoCommit is called and the auto-commit mode is not changed, the call is a no-op.

Parameters:
autoCommit - true to enable auto-commit mode; false to disable it
Throws:
SQLException - if a database access error occurs, setAutoCommit(true) is called while participating in a distributed transaction, or this method is called on a closed connection
See Also:
getAutoCommit()

getAutoCommit

boolean getAutoCommit()
                      throws SQLException
Retrieves the current auto-commit mode for this Connection object.
Returns:
the current state of this Connection object's auto-commit mode
Throws:
SQLException - if a database access error occurs or this method is called on a closed connection
See Also:
setAutoCommit(boolean)

commit

void commit()
            throws SQLException
Makes all changes made since the previous commit/rollback permanent and releases any database locks currently held by this Connection object. This method should be used only when auto-commit mode has been disabled.
Throws:
SQLException - if a database access error occurs, this method is called while participating in a distributed transaction, if this method is called on a closed conection or this Connection object is in auto-commit mode
See Also:
setAutoCommit(boolean)

rollback

void rollback()
              throws SQLException
Undoes all changes made in the current transaction and releases any database locks currently held by this Connection object. This method should be used only when auto-commit mode has been disabled.
Throws:
SQLException - if a database access error occurs, this method is called while participating in a distributed transaction, this method is called on a closed connection or this Connection object is in auto-commit mode
See Also:
setAutoCommit(boolean)

close

void close()
           throws SQLException
Releases this Connection object's database and JDBC resources immediately instead of waiting for them to be automatically released.

Calling the method close on a Connection object that is already closed is a no-op.

It is strongly recommended that an application explicitly commits or rolls back an active transaction prior to calling the close method. If the close method is called and there is an active transaction, the results are implementation-defined.

Throws:
SQLException - SQLException if a database access error occurs

isClosed

boolean isClosed()
                 throws SQLException
Retrieves whether this Connection object has been closed. A connection is closed if the method close has been called on it or if certain fatal errors have occurred. This method is guaranteed to return true only when it is called after the method Connection.close has been called.

This method generally cannot be called to determine whether a connection to a database is valid or invalid. A typical client can determine that a connection is invalid by catching any exceptions that might be thrown when an operation is attempted.

Returns:
true if this Connection object is closed; false if it is still open
Throws:
SQLException - if a database access error occurs

getMetaData

DatabaseMetaData getMetaData()
                             throws SQLException
Retrieves a DatabaseMetaData object that contains metadata about the database to which this Connection object represents a connection. The metadata includes information about the database's tables, its supported SQL grammar, its stored procedures, the capabilities of this connection, and so on.
Returns:
a DatabaseMetaData object for this Connection object
Throws:
SQLException - if a database access error occurs or this method is called on a closed 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

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

setCatalog

void setCatalog(String catalog)
                throws SQLException
Sets the given catalog name in order to select a subspace of this Connection object's database in which to work.

If the driver does not support catalogs, it will silently ignore this request.

Parameters:
catalog - the name of a catalog (subspace in this Connection object's database) in which to work
Throws:
SQLException - if a database access error occurs or this method is called on a closed connection
See Also:
getCatalog()

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
See Also:
setCatalog(java.lang.String)

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
See Also:
DatabaseMetaData.supportsTransactionIsolationLevel(int), getTransactionIsolation()

getTransactionIsolation

int getTransactionIsolation()
                            throws SQLException
Retrieves this Connection object's current transaction isolation level.
Returns:
the current transaction isolation level, which will be one of the following constants: Connection.TRANSACTION_READ_UNCOMMITTED, Connection.TRANSACTION_READ_COMMITTED, Connection.TRANSACTION_REPEATABLE_READ, Connection.TRANSACTION_SERIALIZABLE, or Connection.TRANSACTION_NONE.
Throws:
SQLException - if a database access error occurs or this method is called on a closed connection
See Also:
setTransactionIsolation(int)

getWarnings

SQLWarning getWarnings()
                       throws SQLException
Retrieves the first warning reported by calls on this Connection object. If there is more than one warning, subsequent warnings will be chained to the first one and can be retrieved by calling the method SQLWarning.getNextWarning on the warning that was retrieved previously.

This method may not be called on a closed connection; doing so will cause an SQLException to be thrown.

Note: Subsequent warnings will be chained to this SQLWarning.

Returns:
the first SQLWarning object or null if there are none
Throws:
SQLException - if a database access error occurs or this method is called on a closed connection
See Also:
SQLWarning

clearWarnings

void clearWarnings()
                   throws SQLException
Clears all warnings reported for this Connection object. After a call to this method, the method getWarnings returns null until a new warning is reported for this Connection object.
Throws:
SQLException - SQLException if a database access error occurs or this method is called on a closed connection

createStatement

Statement createStatement(int resultSetType,
                          int resultSetConcurrency)
                          throws SQLException
Creates a Statement object that will generate ResultSet objects with the given type and concurrency. This method is the same as the createStatement method above, but it allows the default result set type and concurrency to be overridden. The holdability of the created result sets can be determined by calling getHoldability().
Parameters:
resultSetType - a result set type; one of ResultSet.TYPE_FORWARD_ONLY, ResultSet.TYPE_SCROLL_INSENSITIVE, or ResultSet.TYPE_SCROLL_SENSITIVE
resultSetConcurrency - a concurrency type; one of ResultSet.CONCUR_READ_ONLY or ResultSet.CONCUR_UPDATABLE
Returns:
a new Statement object that will generate ResultSet objects with the given type and concurrency
Throws:
SQLException - if a database access error occurs, this method is called on a closed connection or the given parameters are not ResultSet constants indicating type and concurrency
SQLFeatureNotSupportedException - if the JDBC driver does not support this method or this method is not supported for the specified result set type and result set concurrency.
Since:
1.2

prepareStatement

PreparedStatement prepareStatement(String sql,
                                   int resultSetType,
                                   int resultSetConcurrency)
                                   throws SQLException
Creates a PreparedStatement object that will generate ResultSet objects with the given type and concurrency. This method is the same as the prepareStatement method above, but it allows the default result set type and concurrency to be overridden. The holdability of the created result sets can be determined by calling getHoldability().
Parameters:
sql - a String object that is the SQL statement to be sent to the database; may contain one or more '?' IN parameters
resultSetType - a result set type; one of ResultSet.TYPE_FORWARD_ONLY, ResultSet.TYPE_SCROLL_INSENSITIVE, or ResultSet.TYPE_SCROLL_SENSITIVE
resultSetConcurrency - a concurrency type; one of ResultSet.CONCUR_READ_ONLY or ResultSet.CONCUR_UPDATABLE
Returns:
a new PreparedStatement object containing the pre-compiled SQL statement that will produce ResultSet objects with the given type and concurrency
Throws:
SQLException - if a database access error occurs, this method is called on a closed connection or the given parameters are not ResultSet constants indicating type and concurrency
SQLFeatureNotSupportedException - if the JDBC driver does not support this method or this method is not supported for the specified result set type and result set concurrency.
Since:
1.2

prepareCall

CallableStatement prepareCall(String sql,
                              int resultSetType,
                              int resultSetConcurrency)
                              throws SQLException
Creates a CallableStatement object that will generate ResultSet objects with the given type and concurrency. This method is the same as the prepareCall method above, but it allows the default result set type and concurrency to be overridden. The holdability of the created result sets can be determined by calling getHoldability().
Parameters:
sql - a String object that is the SQL statement to be sent to the database; may contain on or more '?' parameters
resultSetType - a result set type; one of ResultSet.TYPE_FORWARD_ONLY, ResultSet.TYPE_SCROLL_INSENSITIVE, or ResultSet.TYPE_SCROLL_SENSITIVE
resultSetConcurrency - a concurrency type; one of ResultSet.CONCUR_READ_ONLY or ResultSet.CONCUR_UPDATABLE
Returns:
a new CallableStatement object containing the pre-compiled SQL statement that will produce ResultSet objects with the given type and concurrency
Throws:
SQLException - if a database access error occurs, this method is called on a closed connection or the given parameters are not ResultSet constants indicating type and concurrency
SQLFeatureNotSupportedException - if the JDBC driver does not support this method or this method is not supported for the specified result set type and result set concurrency.
Since:
1.2

getTypeMap

Map<String,Class<?>> getTypeMap()
                                throws SQLException
Retrieves the Map object associated with this Connection object. Unless the application has added an entry, the type map returned will be empty.
Returns:
the java.util.Map object associated with this Connection object
Throws:
SQLException - if a database access error occurs or this method is called on a closed connection
SQLFeatureNotSupportedException - if the JDBC driver does not support this method
Since:
1.2
See Also:
setTypeMap(java.util.Map

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