Java(TM) 2 Platform, Standard Edition, v1.2.2 API Specification: Interface Statement - JDK 5 Documentation v1.2.2, Java 2 SDK 英文文档

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

See Also:: Connection.createStatement(), ResultSet

Method Summary

void addBatch(String sql)
          JDBC 2.0 Adds a SQL command to the current batch of commmands for the statement.

void cancel()
          Cancels this Statement object if both the DBMS and driver support aborting an SQL statement.

void clearBatch()
          JDBC 2.0 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 a SQL statement that may return multiple results.

int[] executeBatch()
          JDBC 2.0 Submits a batch of commands to the database for execution.

ResultSet executeQuery(String sql)
          Executes a SQL statement that returns a single ResultSet.

int executeUpdate(String sql)
          Executes an SQL INSERT, UPDATE or DELETE statement.

Connection getConnection()
          JDBC 2.0 Returns the Connection object that produced this Statement object.

int getFetchDirection()
          JDBC 2.0 Retrieves the direction for fetching rows from database tables that is the default for result sets generated from this Statement object.

int getFetchSize()
          JDBC 2.0 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 can contain.

boolean getMoreResults()
          Moves to a Statement's next result.

int getQueryTimeout()
          Retrieves the number of seconds the driver will wait for a Statement to execute.

ResultSet getResultSet()
          Returns the current result as a ResultSet object.

int getResultSetConcurrency()
          JDBC 2.0 Retrieves the result set concurrency.

int getResultSetType()
          JDBC 2.0 Determine the result set type.

int getUpdateCount()
          Returns the current result as an update count; if the result is a ResultSet or there are no more results, -1 is returned.

SQLWarning getWarnings()
          Retrieves the first warning reported by calls on this Statement.

void setCursorName(String name)
          Defines the SQL cursor name that will be used by subsequent Statement execute methods.

void setEscapeProcessing(boolean enable)
          Sets escape processing on or off.

void setFetchDirection(int direction)
          JDBC 2.0 Gives the driver a hint as to the direction in which the rows in a result set will be processed.

void setFetchSize(int rows)
          JDBC 2.0 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 can contain to the given number.

void setQueryTimeout(int seconds)
          Sets the number of seconds the driver will wait for a Statement to execute to the given number of seconds.

Method Detail

executeQuery

public ResultSet executeQuery(String sql)
                       throws SQLException

Executes a SQL statement that returns a single ResultSet.

Parameters:: sql - typically this is a static SQL SELECT statement
Returns:: a ResultSet that contains the data produced by the 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 - a SQL INSERT, UPDATE or DELETE statement or a SQL statement that returns nothing
Returns:: either the row count for INSERT, UPDATE or DELETE 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 is automatically closed when it is garbage collected. When a Statement is closed, its current ResultSet, 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 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 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 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 to execute to the given number of seconds. If the limit is exceeded, a 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. Subsequent Statement warnings will be chained to this SQLWarning.

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

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

Returns:: the first SQLWarning 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.

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 execute methods. This name can then be used in SQL positioned update/delete statements to identify the current row in the ResultSet 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 than the one which generated the ResultSet 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 a 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 a SQL statement and indicates the form of the first result. You can then use 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; 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; 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 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 it is a ResultSet 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's next result. It returns true if this result is a ResultSet. This method also implicitly closes any current ResultSet obtained with getResultSet. There are no more results when (!getMoreResults() && (getUpdateCount() == -1)

Returns:: true if the next result is a ResultSet; 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

JDBC 2.0 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

getFetchDirection

public int getFetchDirection()
                      throws SQLException

JDBC 2.0 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

setFetchSize

public void setFetchSize(int rows)
                  throws SQLException

JDBC 2.0 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.

getFetchSize

public int getFetchSize()
                 throws SQLException

JDBC 2.0 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

getResultSetConcurrency

public int getResultSetConcurrency()
                            throws SQLException

JDBC 2.0 Retrieves the result set concurrency.

getResultSetType

public int getResultSetType()
                     throws SQLException

JDBC 2.0 Determine the result set type.

addBatch

public void addBatch(String sql)
              throws SQLException

JDBC 2.0 Adds a SQL command to the current batch of commmands for the statement. 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

clearBatch

public void clearBatch()
                throws SQLException

JDBC 2.0 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

executeBatch

public int[] executeBatch()
                   throws SQLException

JDBC 2.0 Submits a batch of commands to the database for execution. This method is optional.

Returns:: an array of update counts containing one element for each command in the batch. The array is ordered according to the order in which commands were inserted into the batch.
Throws:: SQLException - if a database access error occurs or the driver does not support batch statements

getConnection

public Connection getConnection()
                         throws SQLException

JDBC 2.0 Returns the Connection object that produced this Statement object.

Returns:: the connection that produced this statement
Throws:: SQLException - if a database access error occurs