edu.berkeley.cs186.database.query

Class ProjectOperator

java.lang.Object

edu.berkeley.cs186.database.query.QueryOperator

edu.berkeley.cs186.database.query.ProjectOperator

public class ProjectOperator
extends QueryOperator

Nested Class Summary

Nested classes/interfaces inherited from class edu.berkeley.cs186.database.query.QueryOperator

QueryOperator.OperatorType

Constructor Summary

Constructors

Constructor and Description
ProjectOperator(QueryOperator source, List<String> columns, boolean count, String averageColumn, String sumColumn) Creates a new ProjectOperator that reads tuples from source and filters out columns.

Method Summary

Methods

Modifier and Type	Method and Description
protected Schema	computeSchema()
Iterator<Record>	execute() Joins tuples from leftSource with tuples from rightSource based on whether the values in column leftColumnName are equal to tha values in column rightColumnName.

Methods inherited from class edu.berkeley.cs186.database.query.QueryOperator

checkColumnNameEquality, checkSchemaForColumn, getDestination, getOutputSchema, getSource, getType, isGroupBy, isIndexScan, isJoin, isSelect, isSequentialScan, isWhere, setDestination, setOutputSchema, setSource

Methods inherited from class java.lang.Object

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

Constructor Detail

ProjectOperator

public ProjectOperator(QueryOperator source,
              List<String> columns,
              boolean count,
              String averageColumn,
              String sumColumn)
               throws QueryPlanException

Creates a new ProjectOperator that reads tuples from source and filters out columns. Optionally computers an aggregate if it is specified.

Parameters:

source -

columns -

count -

averageColumn -

sumColumn -

Throws:

QueryPlanException

Method Detail

computeSchema

protected Schema computeSchema()
                        throws QueryPlanException

Specified by:

computeSchema in class QueryOperator

Throws:

QueryPlanException

execute

public Iterator<Record> execute()
                         throws QueryPlanException,
                                DatabaseException

Joins tuples from leftSource with tuples from rightSource based on whether the values in column leftColumnName are equal to tha values in column rightColumnName.

Specified by:

execute in class QueryOperator

Returns:

an iterator of records

Throws:

QueryPlanException

DatabaseException