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java.sql
Interface Statement

All Known Subinterfaces:

CallableStatement, PreparedStatement

public interface Statement

The object used for executing a static SQL statement and obtaining the results produced by it.

Only one ResultSet object per Statement object can be open at any point in time. Therefore, if the reading of one ResultSet object is interleaved with the reading of another, each must have been generated by different Statement objects. All statement execute methods implicitly close a statment's current ResultSet object if an open one exists.

See Also:

Connection.createStatement(), ResultSet

Method Summary

void	addBatch(String sql) Adds an SQL command to the current batch of commmands for this Statement object.
void	cancel() Cancels this Statement object if both the DBMS and driver support aborting an SQL statement.
void	clearBatch() Makes the set of commands in the current batch empty.
void	clearWarnings() Clears all the warnings reported on this Statement object.
void	close() Releases this Statement object's database and JDBC resources immediately instead of waiting for this to happen when it is automatically closed.
boolean	execute(String sql) Executes an SQL statement that may return multiple results.
int[]	executeBatch() Submits a batch of commands to the database for execution and if all commands execute successfully, returns an array of update counts.
ResultSet	executeQuery(String sql) Executes an SQL statement that returns a single ResultSet object.
int	executeUpdate(String sql) Executes an SQL INSERT, UPDATE or DELETE statement.
Connection	getConnection() Returns the Connection object that produced this Statement object.
int	getFetchDirection() Retrieves the direction for fetching rows from database tables that is the default for result sets generated from this Statement object.
int	getFetchSize() Retrieves the number of result set rows that is the default fetch size for result sets generated from this Statement object.
int	getMaxFieldSize() Returns the maximum number of bytes allowed for any column value.
int	getMaxRows() Retrieves the maximum number of rows that a ResultSet object can contain.
boolean	getMoreResults() Moves to a Statement object's next result.
int	getQueryTimeout() Retrieves the number of seconds the driver will wait for a Statement object to execute.
ResultSet	getResultSet() Returns the current result as a ResultSet object.
int	getResultSetConcurrency() Retrieves the result set concurrency for ResultSet objects generated by this Statement object.
int	getResultSetType() Retrieves the result set type for ResultSet objects generated by this Statement object.
int	getUpdateCount() Returns the current result as an update count; if the result is a ResultSet object or there are no more results, -1 is returned.
SQLWarning	getWarnings() Retrieves the first warning reported by calls on this Statement object.
void	setCursorName(String name) Defines the SQL cursor name that will be used by subsequent Statement object execute methods.
void	setEscapeProcessing(boolean enable) Sets escape processing on or off.
void	setFetchDirection(int direction) Gives the driver a hint as to the direction in which the rows in a result set will be processed.
void	setFetchSize(int rows) Gives the JDBC driver a hint as to the number of rows that should be fetched from the database when more rows are needed.
void	setMaxFieldSize(int max) Sets the limit for the maximum number of bytes in a column to the given number of bytes.
void	setMaxRows(int max) Sets the limit for the maximum number of rows that any ResultSet object can contain to the given number.
void	setQueryTimeout(int seconds) Sets the number of seconds the driver will wait for a Statement object to execute to the given number of seconds.

Method Detail

executeQuery

public ResultSet executeQuery(String sql)
                       throws SQLException

Executes an SQL statement that returns a single ResultSet object.

Parameters:

sql - typically this is a static SQL SELECT statement

Returns:

a ResultSet object that contains the data produced by the given query; never null

Throws:

SQLException - if a database access error occurs

executeUpdate

public int executeUpdate(String sql)
                  throws SQLException

Executes an SQL INSERT, UPDATE or DELETE statement. In addition, SQL statements that return nothing, such as SQL DDL statements, can be executed.

Parameters:

sql - an SQL INSERT, UPDATE or DELETE statement or an SQL statement that returns nothing

Returns:

either the row count for INSERT, UPDATE or DELETE statements, or 0 for SQL statements that return nothing

Throws:

SQLException - if a database access error occurs

close

public void close()
           throws SQLException

Releases this Statement object's database and JDBC resources immediately instead of waiting for this to happen when it is automatically closed. It is generally good practice to release resources as soon as you are finished with them to avoid tying up database resources.

Note: A Statement object is automatically closed when it is garbage collected. When a Statement object is closed, its current ResultSet object, if one exists, is also closed.

Throws:

SQLException - if a database access error occurs

getMaxFieldSize

public int getMaxFieldSize()
                    throws SQLException

Returns the maximum number of bytes allowed for any column value. This limit is the maximum number of bytes that can be returned for any column value. The limit applies only to BINARY, VARBINARY, LONGVARBINARY, CHAR, VARCHAR, and LONGVARCHAR columns. If the limit is exceeded, the excess data is silently discarded.

Returns:

the current max column size limit; zero means unlimited

Throws:

SQLException - if a database access error occurs

setMaxFieldSize

public void setMaxFieldSize(int max)
                     throws SQLException

Sets the limit for the maximum number of bytes in a column to the given number of bytes. This is the maximum number of bytes that can be returned for any column value. This limit applies only to BINARY, VARBINARY, LONGVARBINARY, CHAR, VARCHAR, and LONGVARCHAR fields. If the limit is exceeded, the excess data is silently discarded. For maximum portability, use values greater than 256.

Parameters:

max - the new max column size limit; zero means unlimited

Throws:

SQLException - if a database access error occurs

getMaxRows

public int getMaxRows()
               throws SQLException

Retrieves the maximum number of rows that a ResultSet object can contain. If the limit is exceeded, the excess rows are silently dropped.

Returns:

the current max row limit; zero means unlimited

Throws:

SQLException - if a database access error occurs

setMaxRows

public void setMaxRows(int max)
                throws SQLException

Sets the limit for the maximum number of rows that any ResultSet object can contain to the given number. If the limit is exceeded, the excess rows are silently dropped.

Parameters:

max - the new max rows limit; zero means unlimited

Throws:

SQLException - if a database access error occurs

setEscapeProcessing

public void setEscapeProcessing(boolean enable)
                         throws SQLException

Sets escape processing on or off. If escape scanning is on (the default), the driver will do escape substitution before sending the SQL to the database. Note: Since prepared statements have usually been parsed prior to making this call, disabling escape processing for prepared statements will have no effect.

Parameters:

enable - true to enable; false to disable

Throws:

SQLException - if a database access error occurs

getQueryTimeout

public int getQueryTimeout()
                    throws SQLException

Retrieves the number of seconds the driver will wait for a Statement object to execute. If the limit is exceeded, a SQLException is thrown.

Returns:

the current query timeout limit in seconds; zero means unlimited

Throws:

SQLException - if a database access error occurs

setQueryTimeout

public void setQueryTimeout(int seconds)
                     throws SQLException

Sets the number of seconds the driver will wait for a Statement object to execute to the given number of seconds. If the limit is exceeded, an SQLException is thrown.

Parameters:

seconds - the new query timeout limit in seconds; zero means unlimited

Throws:

SQLException - if a database access error occurs

cancel

public void cancel()
            throws SQLException

Cancels this Statement object if both the DBMS and driver support aborting an SQL statement. This method can be used by one thread to cancel a statement that is being executed by another thread.

Throws:

SQLException - if a database access error occurs

getWarnings

public SQLWarning getWarnings()
                       throws SQLException

Retrieves the first warning reported by calls on this Statement object. Subsequent Statement object warnings will be chained to this SQLWarning object.

The warning chain is automatically cleared each time a statement is (re)executed.

Note: If you are processing a ResultSet object, any warnings associated with reads on that ResultSet object will be chained on it.

Returns:

the first SQLWarning object or null

Throws:

SQLException - if a database access error occurs

clearWarnings

public void clearWarnings()
                   throws SQLException

Clears all the warnings reported on this Statement object. After a call to this method, the method getWarnings will return null until a new warning is reported for this Statement object.

Throws:

SQLException - if a database access error occurs

setCursorName

public void setCursorName(String name)
                   throws SQLException

Defines the SQL cursor name that will be used by subsequent Statement object execute methods. This name can then be used in SQL positioned update/delete statements to identify the current row in the ResultSet object generated by this statement. If the database doesn't support positioned update/delete, this method is a noop. To insure that a cursor has the proper isolation level to support updates, the cursor's SELECT statement should be of the form 'select for update ...'. If the 'for update' phrase is omitted, positioned updates may fail.

Note: By definition, positioned update/delete execution must be done by a different Statement object than the one which generated the ResultSet object being used for positioning. Also, cursor names must be unique within a connection.

Parameters:

name - the new cursor name, which must be unique within a connection

Throws:

SQLException - if a database access error occurs

execute

public boolean execute(String sql)
                throws SQLException

Executes an SQL statement that may return multiple results. Under some (uncommon) situations a single SQL statement may return multiple result sets and/or update counts. Normally you can ignore this unless you are (1) executing a stored procedure that you know may return multiple results or (2) you are dynamically executing an unknown SQL string. The methods execute, getMoreResults, getResultSet, and getUpdateCount let you navigate through multiple results. The execute method executes an SQL statement and indicates the form of the first result. You can then use the methods getResultSet or getUpdateCount to retrieve the result, and getMoreResults to move to any subsequent result(s).

Parameters:

sql - any SQL statement

Returns:

true if the next result is a ResultSet object; false if it is an update count or there are no more results

Throws:

SQLException - if a database access error occurs

See Also:

getResultSet(), getUpdateCount(), getMoreResults()

getResultSet

public ResultSet getResultSet()
                       throws SQLException

Returns the current result as a ResultSet object. This method should be called only once per result.

Returns:

the current result as a ResultSet object; null if the result is an update count or there are no more results

Throws:

SQLException - if a database access error occurs

See Also:

execute(java.lang.String)

getUpdateCount

public int getUpdateCount()
                   throws SQLException

Returns the current result as an update count; if the result is a ResultSet object or there are no more results, -1 is returned. This method should be called only once per result.

Returns:

the current result as an update count; -1 if the current result is a ResultSet object or there are no more results

Throws:

SQLException - if a database access error occurs

See Also:

execute(java.lang.String)

getMoreResults

public boolean getMoreResults()
                       throws SQLException

Moves to a Statement object's next result. It returns true if this result is a ResultSet object. This method also implicitly closes any current ResultSet object obtained with the method getResultSet.

There are no more results when the following is true:

      (!getMoreResults() && (getUpdateCount() == -1)
 

Returns:

true if the next result is a ResultSet object; false if it is an update count or there are no more results

Throws:

SQLException - if a database access error occurs

See Also:

execute(java.lang.String)

setFetchDirection

public void setFetchDirection(int direction)
                       throws SQLException

Gives the driver a hint as to the direction in which the rows in a result set will be processed. The hint applies only to result sets created using this Statement object. The default value is ResultSet.FETCH_FORWARD.

Note that this method sets the default fetch direction for result sets generated by this Statement object. Each result set has its own methods for getting and setting its own fetch direction.

Parameters:

direction - the initial direction for processing rows

Throws:

SQLException - if a database access error occurs or the given direction is not one of ResultSet.FETCH_FORWARD, ResultSet.FETCH_REVERSE, or ResultSet.FETCH_UNKNOWN

Since:

1.2

See Also:

What Is in the JDBC 2.0 API

getFetchDirection

public int getFetchDirection()
                      throws SQLException

Retrieves the direction for fetching rows from database tables that is the default for result sets generated from this Statement object. If this Statement object has not set a fetch direction by calling the method setFetchDirection, the return value is implementation-specific.

Returns:

the default fetch direction for result sets generated from this Statement object

Throws:

SQLException - if a database access error occurs

Since:

1.2

See Also:

What Is in the JDBC 2.0 API

setFetchSize

public void setFetchSize(int rows)
                  throws SQLException

Gives the JDBC driver a hint as to the number of rows that should be fetched from the database when more rows are needed. The number of rows specified affects only result sets created using this statement. If the value specified is zero, then the hint is ignored. The default value is zero.

Parameters:

rows - the number of rows to fetch

Throws:

SQLException - if a database access error occurs, or the condition 0 <= rows <= this.getMaxRows() is not satisfied.

Since:

1.2

See Also:

What Is in the JDBC 2.0 API

getFetchSize

public int getFetchSize()
                 throws SQLException

Retrieves the number of result set rows that is the default fetch size for result sets generated from this Statement object. If this Statement object has not set a fetch size by calling the method setFetchSize, the return value is implementation-specific.

Returns:

the default fetch size for result sets generated from this Statement object

Throws:

SQLException - if a database access error occurs

Since:

1.2

See Also:

What Is in the JDBC 2.0 API

getResultSetConcurrency

public int getResultSetConcurrency()
                            throws SQLException

Retrieves the result set concurrency for ResultSet objects generated by this Statement object.

Returns:

either ResultSet.CONCUR_READ_ONLY or ResultSet.CONCUR_UPDATABLE

Since:

1.2

See Also:

What Is in the JDBC 2.0 API

getResultSetType

public int getResultSetType()
                     throws SQLException

Retrieves the result set type for ResultSet objects generated by this Statement object.

Returns:

one of ResultSet.TYPE_FORWARD_ONLY, ResultSet.TYPE_SCROLL_INSENSITIVE, or ResultSet.TYPE_SCROLL_SENSITIVE

Since:

1.2

See Also:

What Is in the JDBC 2.0 API

addBatch

public void addBatch(String sql)
              throws SQLException

Adds an SQL command to the current batch of commmands for this Statement object. This method is optional.

Parameters:

sql - typically this is a static SQL INSERT or UPDATE statement

Throws:

SQLException - if a database access error occurs, or the driver does not support batch statements

Since:

1.2

See Also:

What Is in the JDBC 2.0 API

clearBatch

public void clearBatch()
                throws SQLException

Makes the set of commands in the current batch empty. This method is optional.

Throws:

SQLException - if a database access error occurs or the driver does not support batch statements

Since:

1.2

See Also:

What Is in the JDBC 2.0 API

executeBatch

public int[] executeBatch()
                   throws SQLException

Submits a batch of commands to the database for execution and if all commands execute successfully, returns an array of update counts. The int elements of the array that is returned are ordered to correspond to the commands in the batch, which are ordered according to the order in which they were added to the batch. The elements in the array returned by the method executeBatch may be one of the following:

1. A number greater than or equal to zero -- indicates that the command was processed successfully and is an update count giving the number of rows in the database that were affected by the command's execution
2. A value of -2 -- indicates that the command was processed successfully but that the number of rows affected is unknown

   If one of the commands in a batch update fails to execute properly, this method throws a BatchUpdateException, and a JDBC driver may or may not continue to process the remaining commands in the batch. However, the driver's behavior must be consistent with a particular DBMS, either always continuing to process commands or never continuing to process commands. If the driver continues processing after a failure, the array returned by the method BatchUpdateException.getUpdateCounts will contain as many elements as there are commands in the batch, and at least one of the elements will be the following:

3. A value of -3 -- indicates that the command failed to execute successfully and occurs only if a driver continues to process commands after a command fails

A driver is not required to implement this method. The possible implementations and return values have been modified in the Java 2 SDK, Standard Edition, version 1.3 to accommodate the option of continuing to proccess commands in a batch update after a BatchUpdateException obejct has been thrown.

Returns:

an array of update counts containing one element for each command in the batch. The elements of the array are ordered according to the order in which commands were added to the batch.

Throws:

SQLException - if a database access error occurs or the driver does not support batch statements. Throws BatchUpdateException (a subclass of SQLException) if one of the commands sent to the database fails to execute properly or attempts to return a result set.

Since:

1.3

See Also:

What Is in the JDBC 2.0 API

getConnection

public Connection getConnection()
                         throws SQLException

Returns the Connection object that produced this Statement object.

Returns:

the connection that produced this statement

Throws:

SQLException - if a database access error occurs

Since:

1.2

See Also:

What Is in the JDBC 2.0 API