ModSQL
Interface DatabaseTable

All Superinterfaces:

DatabaseTableBase

All Known Implementing Classes:

SelectTable, TableTemplate, Table, AsciiTable

public interface DatabaseTable

extends DatabaseTableBase

Interface to be implemented by classes representing database tables.

To create a new type of database, you need to implement DatabaseTable and DatabaseManager. DatabaseManager creates DatabaseTable objects.

Author:

chris.studholme@utoronto.ca

See Also:

DatabaseManager

Method Summary

boolean	absolute(Object rowid) Move to an absolute rowid in the table.
void	addColumn(String name, int type, int maxlen) Add a new column to the table.
void	addRow() Add a new row to the database.
int	findColumn(String columnName) Map a DatabaseTable column name to a DatabaseTable column index.
int	getColumnCount() What's the number of columns in the DatabaseTable?
int	getColumnDisplaySize(int column) What's the column's normal max width in chars? If the column type is not a string, or the maximum size is not known, this method may return -1.
String	getColumnLabel(int column) What's the suggested column title for use in printouts and displays? In many cases this method should return the same value as getColumnName() below.
String	getColumnName(int column) What's a column's name?
int	getColumnType(int column) What's a column's SQL type?
String	getTableName() What's the table's name?
long	getTableSignature() Calculates a unique signature for this table.
long	getTableSize() Returns the size of the table in bytes.
boolean	isIndexAvailable(int column) Determines if an index is available for the specified column.
boolean	isReadOnly() Is table read-only (ie.
DatabaseIndex	openIndex(int column) Returns an index on the specified column.

Methods inherited from interface ModSQL.DatabaseTableBase

afterLast, beforeFirst, close, commitUpdates, deleteRow, getObject, getRowCount, getRowId, isAfterLast, isBeforeFirst, next, updateObject

Method Detail

openIndex

public DatabaseIndex openIndex(int column)
                        throws DatabaseException

Returns an index on the specified column.

Parameters:

column - index of column to be indexed

Returns:

new DatabaseIndex to use, or null if no index exists

Throws:

DatabaseException - if a database-access error occurs

isIndexAvailable

public boolean isIndexAvailable(int column)
                         throws DatabaseException

Determines if an index is available for the specified column.

Parameters:

column - index of column to be indexed

Returns:

true if index is available, false otherwise

Throws:

DatabaseException - if a database-access error occurs

isReadOnly

public boolean isReadOnly()
                   throws DatabaseException

Is table read-only (ie. no update, insert or delete)?

Returns:

true if so

Throws:

DatabaseException - if a database-access error occurs

getTableName

public String getTableName()
                    throws DatabaseException

What's the table's name?

Returns:

table name or "" if not applicable

Throws:

DatabaseException - if a database-access error occurs

getColumnCount

public int getColumnCount()
                   throws DatabaseException

What's the number of columns in the DatabaseTable?

Returns:

the number

Throws:

DatabaseException - if a database-access error occurs

getTableSize

public long getTableSize()
                  throws DatabaseException

Returns the size of the table in bytes. This method may return an approximation, or -1 is the size is not known.

Returns:

table size in bytes

Throws:

DatabaseException - if a database-access error occurs

getTableSignature

public long getTableSignature()
                       throws DatabaseException

Calculates a unique signature for this table.

The signature should depend on values of:

• table size
• number of data files
• order of data files
• number of columns
• types and order of columns

Any change to the table that would invalidate an index should also change the signature. If this table will never be indexed, this method may return 0.

Returns:

unique signature for table

Throws:

DatabaseException - if a database-access error occurs

findColumn

public int findColumn(String columnName)
               throws DatabaseException

Map a DatabaseTable column name to a DatabaseTable column index. Columns should be sequentially numbered 1,2,3,etc.

Parameters:

columnName - the name of the column

Returns:

the column index

Throws:

DatabaseException - if a database-access error occurs

getColumnDisplaySize

public int getColumnDisplaySize(int column)
                         throws DatabaseException

What's the column's normal max width in chars? If the column type is not a string, or the maximum size is not known, this method may return -1.

Parameters:

column - the first column is 1, the second is 2, ...

Returns:

max width

Throws:

DatabaseException - if a database-access error occurs

getColumnLabel

public String getColumnLabel(int column)
                      throws DatabaseException

What's the suggested column title for use in printouts and displays? In many cases this method should return the same value as getColumnName() below.

Parameters:

column - the first column is 1, the second is 2, ...

Returns:

true if so

Throws:

DatabaseException - if a database-access error occurs

getColumnName

public String getColumnName(int column)
                     throws DatabaseException

What's a column's name?

Parameters:

column - the first column is 1, the second is 2, ...

Returns:

column name

Throws:

DatabaseException - if a database-access error occurs

getColumnType

public int getColumnType(int column)
                  throws DatabaseException

What's a column's SQL type?

Parameters:

column - the first column is 1, the second is 2, ...

Returns:

SQL type

Throws:

DatabaseException - if a database-access error occurs

See Also:

Types

addColumn

public void addColumn(String name,
                      int type,
                      int maxlen)
               throws DatabaseException

Add a new column to the table.

Parameters:

name - column name

type - SQL type

maxlen - length of data (varying columns only)

Throws:

DatabaseException - if a database-access error occurs

See Also:

Types

addRow

public void addRow()
            throws DatabaseException

Add a new row to the database. This method creates a new row which must have columns set using updateObject().

Throws:

DatabaseException - if a database-access error occurs

absolute

public boolean absolute(Object rowid)
                 throws DatabaseException

Move to an absolute rowid in the table.

Parameters:

rowid - id of row to seek

Returns:

true if row was found, false otherwise

Throws:

DatabaseException - if a database-access error occurs