ModSQL
Interface Table

All Known Implementing Classes:

Select, LiteralTable

public interface Table

A table is zero or more rows. Each row consists of one or more columns.

Author:

chris.studholme@utoronto.ca

Method Summary

void	beforeFirst() Reset the table to before the first row.
int	getColumnCount() Returns the number of columns in the table.
String	getColumnName(int column) Get the name of a column.
int	getMaxResultSize(int column) Return the maximum number of characters String values in the specified column will have.
Object	getObject(int column) Get the value of a column in the current row as a Java object.
Object[]	getRow() Get the current row as an array of Objects.
long	getRowCount() Get count of number of rows, if known.
int	getSQLType(int column) Return the SQL type of the specified column.
boolean	isConstant() Determine if this table is constant.
boolean	next() The table is initially positioned before its first row; the first call to next makes the first row the current row; the second call makes the second row the current row, etc.
void	optimize() Prepare the table for use.
void	registerWith(Object o) Some functions (most notably IndirectValue) needs to register themselves before optimize() can be called.
String	toString(boolean with_brackets) Return human readable description of table.

Method Detail

registerWith

public void registerWith(Object o)
                  throws SQLException

Some functions (most notably IndirectValue) needs to register themselves before optimize() can be called. This method must call the registerWith() method on all Function objects contained within. Most implementations will simply pass this call on to all contained Function objects.

Parameters:

o - object to register with

Throws:

SQLException - if an error occurs

optimize

public void optimize()
              throws SQLException

Prepare the table for use. This method should call optimize() for all Function objects contained within.

Throws:

SQLException - if an error occurs

toString

public String toString(boolean with_brackets)

Return human readable description of table.

Parameters:

with_brackets - bracket the expression

Returns:

String representing table

isConstant

public boolean isConstant()
                   throws SQLException

Determine if this table is constant.

This method can only be called after optimize().

Returns:

true if the table is constant

Throws:

SQLException - if an error occurs

getRowCount

public long getRowCount()
                 throws SQLException

Get count of number of rows, if known. This method is best called immediately after a call to beforeFirst(); however, it still might return -1 in that case too.

This method can only be called after optimize().

Returns:

number of rows or -1 if count is not known

Throws:

SQLException - if an error occurs

getColumnCount

public int getColumnCount()
                   throws SQLException

Returns the number of columns in the table. The returned value must be greater than zero.

This method can only be called after optimize().

Returns:

number of columns in table

Throws:

SQLException - if an error occurs

getColumnName

public String getColumnName(int column)
                     throws SQLException

Get the name of a column.

This method can only be called after optimize().

Parameters:

column - column number (starting from zero)

Returns:

name of column (or null if column has no name)

Throws:

SQLException - if an error occurs

getSQLType

public int getSQLType(int column)
               throws SQLException

Return the SQL type of the specified column.

This method can only be called after optimize().

Parameters:

column - column number (starting from zero)

Returns:

SQL type of data to be returned

Throws:

SQLException - if an error occurs

getMaxResultSize

public int getMaxResultSize(int column)
                     throws SQLException

Return the maximum number of characters String values in the specified column will have. If the column is not of String type or if the maximum length is not known, -1 should be returned.

This method can only be called after optimize().

Parameters:

column - column number (starting from zero)

Returns:

maximum size of String returned or -1 if unknown

Throws:

SQLException - if an error occurs

beforeFirst

public void beforeFirst()
                 throws SQLException

Reset the table to before the first row. After a call to this method, next() should advance to the first row in the table.

This method can only be called after optimize().

Throws:

SQLException - if an error occurs

next

public boolean next()
             throws SQLException,
                    EndOfTable

The table is initially positioned before its first row; the first call to next makes the first row the current row; the second call makes the second row the current row, etc.

This method can only be called after optimize().

Returns:

true if the new current row is valid; false if there are no more rows

Throws:

SQLException - if an error occurs

EndOfTable - if the table is advanced beyond that last row

getRow

public Object[] getRow()
                throws SQLException,
                       EndOfTable

Get the current row as an array of Objects.

This method can only be called after optimize().

Returns:

array of objects or null if current row is not valid

Throws:

SQLException - if an error occurs

EndOfTable - if the table is advanced beyond that last row

getObject

public Object getObject(int column)
                 throws SQLException,
                        EndOfTable

Get the value of a column in the current row as a Java object. This method will throw an exception if the current row is not valid.

This method can only be called after optimize().

Parameters:

column - column number (starting from zero)

Returns:

an Object holding the column value

Throws:

SQLException - if an error occurs

EndOfTable - if the table is advanced beyond that last row