org.tentackle.db
Class Query

java.lang.Object
  org.tentackle.db.Query

Direct Known Subclasses:

AppDbQuery

public class Query
extends Object

A database query.
Combines the generation of an sql-string and parameter set for the ResultSetWrapper. Useful for one-time queries entered by the user.
Notice that by default the underlying prepared statement is closed when the resultset (or cursor) is closed by the application. You can change that behaviour, however.

Author:

harald

Constructor Summary

Query()
Creates a query.

Method Summary

void	add(String sql, Object... data) Appends an sql-part and corresponding parameters to this query.
void	apply(Db db, PreparedStatementWrapper st) Applies the query parameters to the statement. Optionally applies limit, offset as well.
ResultSetWrapper	execute(Db db) Executes the query with ResultSet.TYPE_FORWARD_ONLY and ResultSet.CONCUR_READ_ONLY.
ResultSetWrapper	execute(Db db, int resultSetType) Executes the query with ResultSet.CONCUR_READ_ONLY.
ResultSetWrapper	execute(Db db, int resultSetType, int resultSetConcurrency) Executes the query.
int	getEstimatedRowCount(Db db) Gets the number of objects returned by this query.
int	getFetchSize() Gets the fetchsize.
int	getLimit() Gets the maximum number of rows for this query.
int	getMaxRows() Gets the maximum row count for this cursor
int	getOffset() Gets the offset of this query.
String	getSql(Db db) Gets the SQL-String of this query. Optionally modifies the sql query according to limit and offset.
boolean	isCloseStatementOnClose() Returns whether statement is closed when result set is closed.
void	setCloseStatementOnClose(boolean closeStatementOnClose) Sets whether to close the statement when resultset is closed.
void	setFetchSize(int fetchSize) Sets the optional fetchsize.
void	setLimit(int limit) Sets the maximum number of rows to retrieve for this query.
void	setMaxRows(int maxRows) Sets the optional maximum row count for this cursor.
void	setOffset(int offset) Sets an offset, i.e.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Query

public Query()

Creates a query.

Method Detail

setOffset

public void setOffset(int offset)

Sets an offset, i.e. number of rows to skip in a query. By default the offset is 0.

Parameters:

offset - the offset, 0 to disable

getOffset

public int getOffset()

Gets the offset of this query.

Returns:

the number of rows to skip, 0 if no offset

setLimit

public void setLimit(int limit)

Sets the maximum number of rows to retrieve for this query.

Parameters:

limit - the maximum number of rows, 0 if ulimited (default)

getLimit

public int getLimit()

Gets the maximum number of rows for this query.

Returns:

the maximum number of rows, 0 if ulimited (default)

add

public void add(String sql,
                Object... data)

Appends an sql-part and corresponding parameters to this query.

 Example: add(" AND FIELD_ID=?", object.getId());
          add(" AND FIELD_MONEY=?", object.getAmount());
 

Parameters:

sql - is the SQL-string

data - is an array of parameters

setCloseStatementOnClose

public void setCloseStatementOnClose(boolean closeStatementOnClose)

Sets whether to close the statement when resultset is closed. The default is to close.

Parameters:

closeStatementOnClose - true if statement is closed, false = left open

isCloseStatementOnClose

public boolean isCloseStatementOnClose()

Returns whether statement is closed when result set is closed.

Returns:

true if statement is closed, false = left open

setFetchSize

public void setFetchSize(int fetchSize)

Sets the optional fetchsize. 0 = drivers default.

Parameters:

fetchSize - the fetchsize

See Also:

ResultSetWrapper.setFetchSize(int)

getFetchSize

public int getFetchSize()

Gets the fetchsize.

Returns:

the fetchsize

See Also:

ResultSetWrapper.getFetchSize()

setMaxRows

public void setMaxRows(int maxRows)

Sets the optional maximum row count for this cursor.

Parameters:

maxRows - the max rows, 0 = no limit

getMaxRows

public int getMaxRows()

Gets the maximum row count for this cursor

Returns:

the max rows, 0 = no limit

execute

public ResultSetWrapper execute(Db db,
                                int resultSetType,
                                int resultSetConcurrency)

Executes the query.

Parameters:

db - is the database connection

resultSetType - is one of ResultSet.TYPE_...

resultSetConcurrency - is one of ResultSet.CONCUR_..

Returns:

the result set

execute

public ResultSetWrapper execute(Db db,
                                int resultSetType)

Executes the query with ResultSet.CONCUR_READ_ONLY.

Parameters:

db - is the database connection

resultSetType - is one of ResultSet.TYPE_...

Returns:

the result set

execute

public ResultSetWrapper execute(Db db)

Executes the query with ResultSet.TYPE_FORWARD_ONLY and ResultSet.CONCUR_READ_ONLY.

Parameters:

db - is the database connection

Returns:

the result set

getEstimatedRowCount

public int getEstimatedRowCount(Db db)

Gets the number of objects returned by this query.

This is not done by retrieving all rows but by a "SELECT COUNT(*)". Applications may use this in conjunction with limit and offset for pagination (in web pages, for example).

Parameters:

db - the db connection

Returns:

the number of rows for this query

getSql

public String getSql(Db db)

Gets the SQL-String of this query.
Optionally modifies the sql query according to limit and offset.

Parameters:

db - the db connection

Returns:

the sql string

apply

public void apply(Db db,
                  PreparedStatementWrapper st)

Applies the query parameters to the statement.
Optionally applies limit, offset as well.

Parameters:

db - the database connection

st - the prepared statement