Class SQLStatement

java.lang.Object

SQLStatement

Direct Known Subclasses:

BeginStatement, CommitStatement, CreateStatement, DeleteStatement, DropStatement, InsertStatement, RollbackStatement, SelectStatement, UpdateStatement

public abstract class SQLStatement
extends Object

An abstract class that represents a SQL statement. An object from a subclass of this class is returned by the SQL parser, and it can be executed by invoking its execute() method.

Constructor Summary

Constructors

Constructor and Description
SQLStatement() Default constructor, used in the constructors for subclasses that represent statements that don't have any associated state (i.e., begin, commit, and rollback).
SQLStatement(ArrayList<Table> tl, ArrayList<Column> cl, ConditionalExpression w) Constructor used in the constructors for subclasses that represent statements that specify table(s), column(s), and a conditional expression (i.e., select, update, and delete statements).
SQLStatement(Table t) Constructor used in the constructors for subclasses that represent statements that only specify a table (i.e., drop table statements).
SQLStatement(Table t, ArrayList<Column> cl) Constructor used in the constructors for subclasses that represent statements that only specify a table and some column information (i.e., create table statements).
SQLStatement(Table t, ArrayList<Column> cl, ArrayList<Object> vl) Constructor used in the constructors for subclasses that represent statements that specify a single table, one or more column(s), and values for those columns (i.e., insert statements).
SQLStatement(Table t, ArrayList<Column> cl, ConditionalExpression w) Constructor used in the constructors for subclasses that represent statements that specify a single table, one or more column(s), and a conditional expression (i.e., update and delete statements).

Method Summary

Modifier and Type	Method and Description
void	addColumn(Column c) Adds a column to the list of columns for this statement.
void	addColumnVal(Object cv) Adds a column value to the list of column values for this statement.
void	addTable(Table t) Adds a table to the list of tables for this statement.
abstract void	execute() Executes this SQL statement.
Column	getColumn(int i) Returns the column with the specified index in this statement.
Object	getColumnVal(int i) Returns the column value with the specified index in this statement.
Table	getTable(int i) Returns the table with the specified index in this statement.
ConditionalExpression	getWhere()
Column	getWhereColumn(int i) Returns the column with the specified index from the WHERE clause of this statement.
int	numColumns() Returns the number of columns specified in this statement.
int	numColumnVals() Returns the number of column values specified in this statement.
int	numTables() Returns the number of tables specified in this statement.
int	numWhereColumns() Returns the number of columns in the WHERE clause of this statement, or 0 if there is no WHERE clause.
String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

SQLStatement

public SQLStatement()

Default constructor, used in the constructors for subclasses that represent statements that don't have any associated state (i.e., begin, commit, and rollback).

SQLStatement

public SQLStatement(Table t)

Constructor used in the constructors for subclasses that represent statements that only specify a table (i.e., drop table statements).

SQLStatement

public SQLStatement(Table t,
                    ArrayList<Column> cl)

Constructor used in the constructors for subclasses that represent statements that only specify a table and some column information (i.e., create table statements).

SQLStatement

public SQLStatement(ArrayList<Table> tl,
                    ArrayList<Column> cl,
                    ConditionalExpression w)

Constructor used in the constructors for subclasses that represent statements that specify table(s), column(s), and a conditional expression (i.e., select, update, and delete statements).

SQLStatement

public SQLStatement(Table t,
                    ArrayList<Column> cl,
                    ConditionalExpression w)

Constructor used in the constructors for subclasses that represent statements that specify a single table, one or more column(s), and a conditional expression (i.e., update and delete statements).

SQLStatement

public SQLStatement(Table t,
                    ArrayList<Column> cl,
                    ArrayList<Object> vl)

Constructor used in the constructors for subclasses that represent statements that specify a single table, one or more column(s), and values for those columns (i.e., insert statements).

Method Detail

execute

public abstract void execute()
                      throws DatabaseException,
                             DeadlockException

Executes this SQL statement.

Throws:

DeadlockException - if deadlock occurs while accessing an underlying database.

DatabaseException - if Berkeley DB encounters another problem accessing an underlying database.

addTable

public void addTable(Table t)

Adds a table to the list of tables for this statement.

Parameters:

t - the table

addColumn

public void addColumn(Column c)

Adds a column to the list of columns for this statement.

Parameters:

c - the column

addColumnVal

public void addColumnVal(Object cv)

Adds a column value to the list of column values for this statement.

Parameters:

cv - the column value

getTable

public Table getTable(int i)

Returns the table with the specified index in this statement. The first table has an index of 0.

Returns:

the table

Throws:

RuntimeException - if the statement does not specify any tables

IndexOutOfBoundsException - if the specified index is invalid

getColumn

public Column getColumn(int i)

Returns the column with the specified index in this statement. The first column has an index of 0. This method cannot be used to obtain columns from a WHERE clause. Use getWhereColumn() instead.

Returns:

the column

Throws:

RuntimeException - if the statement does not specify any columns

IndexOutOfBoundsException - if the specified index is invalid

getColumnVal

public Object getColumnVal(int i)

Returns the column value with the specified index in this statement. The first column value has an index of 0. This method cannot be used to obtain values from an UPDATE statement. Instead, get the column using getColumn() and then use its getUpdateVal() method.

Returns:

the column value

Throws:

RuntimeException - if the statement does not specify any column values

IndexOutOfBoundsException - if the specified index is invalid

getWhereColumn

public Column getWhereColumn(int i)

Returns the column with the specified index from the WHERE clause of this statement. The first such column has an index of 0.

Returns:

the column

Throws:

RuntimeException - if the statement does not have a WHERE clause

IndexOutOfBoundsException - if the specified index is invalid

getWhere

public ConditionalExpression getWhere()

numTables

public int numTables()

Returns the number of tables specified in this statement.

Returns:

the number of tables

numColumns

public int numColumns()

Returns the number of columns specified in this statement. This does not include columns specified in the WHERE clause. Use numWhereColumns() to get that value.

Returns:

the number of columns

numWhereColumns

public int numWhereColumns()

Returns the number of columns in the WHERE clause of this statement, or 0 if there is no WHERE clause.

Returns:

the number of columns in the WHERE clause

numColumnVals

public int numColumnVals()

Returns the number of column values specified in this statement. This method cannot be used to obtain the number of values in an UPDATE statement. Instead, use the numColumns() method.

Returns:

the number of column values

toString

public String toString()

Overrides:

toString in class Object