Package com.mckoi.database.interpret

Class Planner.QuerySelectColumnSet

java.lang.Object

com.mckoi.database.interpret.Planner.QuerySelectColumnSet

Enclosing class:

Planner

private static class Planner.QuerySelectColumnSet
extends java.lang.Object

A container object for the set of SelectColumn objects selected in a query.

Field Summary

Fields

Modifier and Type	Field	Description
(package private) int	aggregate_count	The count of aggregate and constant columns included in the result set.
(package private) int	constant_count	The count of aggregate and constant columns included in the result set.
private TableExpressionFromSet	from_set	The tables we are selecting from.
(package private) java.util.ArrayList	function_col_list	The list of functions in this column set.
private static TableName	FUNCTION_TABLE_NAME	The name of the table where functions are defined.
private int	running_fun_number	The current number of 'FUNCTIONTABLE.' columns in the table.
(package private) java.util.ArrayList	s_col_list	The list of SelectColumn.

Constructor Summary

Constructors

Constructor	Description
QuerySelectColumnSet(TableExpressionFromSet from_set)	Constructor.

Method Summary

Modifier and Type	Method	Description
(package private) void	addAllFromTable(FromTableInterface table)	Adds all columns from the given FromTableInterface object.
(package private) Variable	addHiddenFunction(java.lang.String fun_alias, Expression function, QueryContext context)	Adds a new hidden function into the column set.
(package private) void	prepare(QueryContext context)	Resolves all variable objects in each column.
private void	prepareSelectColumn(SelectColumn col, QueryContext context)	Prepares the given SelectColumn by fully qualifying the expression and allocating it correctly within this context.
(package private) void	selectAllColumnsFromAllSources()	Sets up this queriable with all columns from all table sources.
(package private) void	selectAllColumnsFromSource(TableName table_name)	Adds all column from the given table object.
(package private) void	selectSingleColumn(SelectColumn col)	Adds a single SelectColumn to the list of output columns from the query.

Methods inherited from class java.lang.Object

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

Field Detail

FUNCTION_TABLE_NAME

private static TableName FUNCTION_TABLE_NAME

The name of the table where functions are defined.

from_set

private TableExpressionFromSet from_set

The tables we are selecting from.

s_col_list

java.util.ArrayList s_col_list

The list of SelectColumn.

function_col_list

java.util.ArrayList function_col_list

The list of functions in this column set.

running_fun_number

private int running_fun_number

The current number of 'FUNCTIONTABLE.' columns in the table. This is incremented for each custom column.

aggregate_count

int aggregate_count

The count of aggregate and constant columns included in the result set. Aggregate columns are, (count(*), avg(cost_of) * 0.75, etc). Constant columns are, (9 * 4, 2, (9 * 7 / 4) + 4, etc).

constant_count

int constant_count

The count of aggregate and constant columns included in the result set. Aggregate columns are, (count(*), avg(cost_of) * 0.75, etc). Constant columns are, (9 * 4, 2, (9 * 7 / 4) + 4, etc).

Constructor Detail

QuerySelectColumnSet

public QuerySelectColumnSet(TableExpressionFromSet from_set)

Constructor.

Method Detail

selectSingleColumn

void selectSingleColumn(SelectColumn col)

Adds a single SelectColumn to the list of output columns from the query.

Note that at this point the the information in the given SelectColumn may not be completely qualified.

addAllFromTable

void addAllFromTable(FromTableInterface table)

Adds all columns from the given FromTableInterface object.

selectAllColumnsFromSource

void selectAllColumnsFromSource(TableName table_name)

Adds all column from the given table object. This is used to set up the columns that are to be viewed as the result of the select statement.

selectAllColumnsFromAllSources

void selectAllColumnsFromAllSources()

Sets up this queriable with all columns from all table sources.

addHiddenFunction

Variable addHiddenFunction(java.lang.String fun_alias,
                           Expression function,
                           QueryContext context)

Adds a new hidden function into the column set. This is intended to be used for implied functions. For example, a query may have a function in a GROUP BY clause. It's desirable to include the function in the column set but not in the final result.

Returns an absolute Variable object that can be used to reference this hidden column.

prepareSelectColumn

private void prepareSelectColumn(SelectColumn col,
                                 QueryContext context)
                          throws DatabaseException

Prepares the given SelectColumn by fully qualifying the expression and allocating it correctly within this context.

Throws:

DatabaseException

prepare

void prepare(QueryContext context)
      throws DatabaseException

Resolves all variable objects in each column.

Throws:

DatabaseException