adql.db

Class DBCommonColumn

java.lang.Object

adql.db.DBCommonColumn

All Implemented Interfaces:

DBColumn

public class DBCommonColumn
extends java.lang.Object
implements DBColumn

This is a special column which exists only after a NATURAL JOIN or a JOIN ... USING between two tables. It lets unify several columns of the joined tables in a single column. Thus, the writer of an ADQL query can use the column name without table prefix (since after the join there will be only one) or with a prefix table of the joined tables. The list of all covered tables is stored in this object and can be extended in case of several JOINs.

Since:

1.2

Version:

1.3 (05/2015)

Author:

Grégory Mantelet (ARI) - gmantele@ari.uni-heidelberg.de

Field Summary

Fields

Modifier and Type	Field and Description
protected DBColumn	generalColumnDesc
protected java.util.ArrayList<DBTable>	lstCoveredTables

Constructor Summary

Constructors

Constructor and Description
DBCommonColumn(DBColumn leftCol, DBColumn rightCol) Create a column which merges both of the given columns.
DBCommonColumn(DBCommonColumn toCopy, java.lang.String dbName, java.lang.String adqlName) Constructor by copy.

Method Summary

Modifier and Type	Method and Description
protected void	addCoveredTable(DBTable table) Add a table that this common column must cover from now.
DBColumn	copy(java.lang.String dbName, java.lang.String adqlName, DBTable dbTable) WARNING: This copy function does not make a real copy of this DBCommonColumn ! It returns a modified copy of the general column description it contains.
java.lang.String	getADQLName() Gets the name of this column (without any prefix and double-quotes).
java.util.Iterator<DBTable>	getCoveredTables() Get an iterator over the list of all tables covered by this common column.
DBType	getDatatype() Get the type of this column (as closed as possible from the "database" type).
java.lang.String	getDBName() Gets the name of this column in the "database".
DBTable	getTable() Gets the table which contains this DBColumn.

Methods inherited from class java.lang.Object

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

Field Detail

generalColumnDesc

protected DBColumn generalColumnDesc

lstCoveredTables

protected java.util.ArrayList<DBTable> lstCoveredTables

Constructor Detail

DBCommonColumn

public DBCommonColumn(DBColumn leftCol,
                      DBColumn rightCol)
               throws UnresolvedJoinException

Create a column which merges both of the given columns. This special DBColumn implementation is not associated with one table, and can be listed in a DBTable ONLY IF the latter is the result of a sub-query (see ADQLQuery.getResultingColumns()). A column resulting from a tables join is common only to the joined tables. That's why a list of all tables covered by this column is created or update at each merge. It can be accessed thanks to getCoveredTables(). Note: In the case one or both of the columns to join are DBCommonColumn, the list of their covered tables are also merged.

Parameters:

leftCol - Column of the left join table. May be a DBCommonColumn.

rightCol - Column of the right join table. May be a DBCommonColumn.

Throws:

UnresolvedJoinException - If the type of the two given columns are not roughly (just testing numeric, string or geometry) compatible.

DBCommonColumn

public DBCommonColumn(DBCommonColumn toCopy,
                      java.lang.String dbName,
                      java.lang.String adqlName)

Constructor by copy. It returns a copy of this instance of DBCommonColumn. Note: The list of covered tables is NOT deeply copied!

Parameters:

toCopy - The DBCommonColumn to copy.

dbName - The new DB name of this DBCommonColumn.

adqlName - The new ADQL name of this DBCommonColumn.

Method Detail

getADQLName

public final java.lang.String getADQLName()

Description copied from interface: DBColumn

Gets the name of this column (without any prefix and double-quotes).

Specified by:

getADQLName in interface DBColumn

Returns:

Its ADQL name.

getDBName

public final java.lang.String getDBName()

Description copied from interface: DBColumn

Gets the name of this column in the "database".

Specified by:

getDBName in interface DBColumn

Returns:

Its DB name.

getDatatype

public final DBType getDatatype()

Description copied from interface: DBColumn

Get the type of this column (as closed as possible from the "database" type).

Note: The returned type should be as closed as possible from a type listed by the IVOA in the TAP protocol description into the section UPLOAD.

Specified by:

getDatatype in interface DBColumn

Returns:

Its type.

getTable

public final DBTable getTable()

Description copied from interface: DBColumn

Gets the table which contains this DBColumn.

Specified by:

getTable in interface DBColumn

Returns:

Its table or null if no table is specified.

getCoveredTables

public final java.util.Iterator<DBTable> getCoveredTables()

Get an iterator over the list of all tables covered by this common column.

Returns:

Iterator over all covered tables.

addCoveredTable

protected void addCoveredTable(DBTable table)

Add a table that this common column must cover from now. Warning: no unicity check is never done !

Parameters:

table - Table to add in the covered tables list.

copy

public DBColumn copy(java.lang.String dbName,
                     java.lang.String adqlName,
                     DBTable dbTable)

WARNING: This copy function does not make a real copy of this DBCommonColumn ! It returns a modified copy of the general column description it contains. Note: To make a real copy of this DBCommonColumn use the Constructor by copy DBCommonColumn(DBCommonColumn, String, String).

Specified by:

copy in interface DBColumn

Parameters:

dbName - Its new DB name.

adqlName - Its new ADQL name.

dbTable - Its new DBTable

Returns:

A modified copy of the general column description this common column represents.

See Also:

DBColumn.copy(java.lang.String, java.lang.String, adql.db.DBTable)