# Interface JoinRowSet

All Superinterfaces:
  `AutoCloseable, CachedRowSet, Joinable, ResultSet, RowSet, WebRowSet, Wrapper`

public interface JoinRowSet extends WebRowSet
The `JoinRowSet` interface provides a mechanism for combining related data from different `RowSet` objects into one `JoinRowSet` object, which represents an SQL `JOIN`. In other words, a `JoinRowSet` object acts as a container for the data from `RowSet` objects that form an SQL `JOIN` relationship.

The `Joinable` interface provides the methods for setting, retrieving, and unsetting a match column, the basis for establishing an SQL `JOIN` relationship. The match column may alternatively be set by supplying it to the appropriate version of the `JointRowSet` method `addRowSet`.

## 1.0 Overview

Disconnected `RowSet` objects (`CachedRowSet` objects and implementations extending the `CachedRowSet` interface) do not have a standard way to establish an SQL `JOIN` between `RowSet` objects without the expensive operation of reconnecting to the data source. The `JoinRowSet` interface is specifically designed to address this need.

Any `RowSet` object can be added to a `JoinRowSet` object to become part of an SQL `JOIN` relationship. This means that both connected and disconnected `RowSet` objects can be part of a `JOIN`. `RowSet` objects operating in a connected environment (`JdbcRowSet` objects) are encouraged to use the database to which they are already connected to establish SQL `JOIN` relationships between tables directly. However, it is possible for a `JdbcRowSet` object to be added to a `JoinRowSet` object if necessary.

Any number of `RowSet` objects can be added to an instance of `JoinRowSet` provided that they can be related in an SQL `JOIN`. By definition, the SQL `JOIN` statement is used to combine the data contained in two or more relational database tables based upon a common attribute. The `Joinable` interface provides the methods for establishing a common attribute, which is done by setting a match column. The match column commonly coincides with the primary key, but there is no requirement that the match column be the same as the primary key. By establishing and then enforcing column matches, a `JoinRowSet` object establishes `JOIN` relationships between `RowSet` objects without the assistance of an available relational database.

The type of `JOIN` to be established is determined by setting one of the `JoinRowSet` constants using the method `setJoinType`. The following SQL `JOIN` types can be set:

- `CROSS_JOIN`
- `FULL_JOIN`
- `INNER_JOIN` - the default if no `JOIN` type has been set
- `LEFT_OUTER_JOIN`
- `RIGHT_OUTER_JOIN`

Note that if no type is set, the `JOIN` will automatically be an inner join. The comments for the fields in the `JoinRowSet` interface explain these `JOIN` types, which are standard SQL `JOIN` types.

## 2.0 Using a `JoinRowSet` Object for Creating a `JOIN`

When a `JoinRowSet` object is created, it is empty. The first `RowSet` object to be added becomes the basis for the `JOIN` relationship. Applications must determine which column in each of the `RowSet` objects to be added to the `JoinRowSet` object should be the match column. All of the `RowSet` objects must contain a match column, and the values in each match column must be ones that can be compared to values in the other match columns. The columns do not have to have the same name, though they often do, and they do not have to store the exact same data type as long as the data types can be compared.

A match column can be set in two ways:

- By calling the `Joinable` method `setMatchColumn`
  This is the only method that can set the match column before a `RowSet` object is added to a `JoinRowSet` object. The `RowSet` object must have implemented the `Joinable` interface in order to use the method `setMatchColumn`. Once the match column value has been set, this method can be used to reset the match column at any time.
- By calling one of the versions of the `JoinRowSet` method `addRowSet` that takes a column name or number (or an array of column names or numbers)
  Four of the five `addRowSet` methods take a match column as a parameter. These four methods set or reset the match column at the time a `RowSet` object is being added to a `JoinRowSet` object.

## 3.0 Sample Usage

The following code fragment adds two `CachedRowSet` objects to a `JoinRowSet` object. Note that in this example, no SQL `JOIN` type is set, so the default `JOIN` type, which is INNER_JOIN, is established.

In the following code fragment, the table `EMPLOYEES`, whose match column is set to the first column (`EMP_ID`), is added to the `JoinRowSet` object jrs. Then the table `ESSP_BONUS_PLAN`, whose match column is likewise the `EMP_ID` column, is added. When this second table is added to jrs, only the rows in `ESSP_BONUS_PLAN` whose `EMP_ID` value matches an `EMP_ID` value in the `EMPLOYEES` table are added. In this case, everyone in the bonus plan is an employee, so all of the rows in the table `ESSP_BONUS_PLAN` are added to the `JoinRowSet` object. In this example, both `CachedRowSet` objects being added have implemented the `Joinable` interface and can therefore call the `Joinable` method `setMatchColumn`.

        JoinRowSet jrs = new JoinRowSetImpl();

        ResultSet rs1 = stmt.executeQuery("SELECT * FROM EMPLOYEES");
        CachedRowSet empl = new CachedRowSetImpl();
        empl.populate(rs1);
        empl.setMatchColumn(1);
        jrs.addRowSet(empl);

        ResultSet rs2 = stmt.executeQuery("SELECT * FROM ESSP_BONUS_PLAN");
        CachedRowSet bonus = new CachedRowSetImpl();
        bonus.populate(rs2);
        bonus.setMatchColumn(1); // EMP_ID is the first column
        jrs.addRowSet(bonus);

At this point, jrs is an inside JOIN of the two `RowSet` objects based on their `EMP_ID` columns. The application can now browse the combined data as if it were browsing one single `RowSet` object. Because jrs is itself a `RowSet` object, an application can navigate or modify it using `RowSet` methods.

        jrs.first();
        int employeeID = jrs.getInt(1);
        String employeeName = jrs.getString(2);

Note that because the SQL `JOIN` must be enforced when an application adds a second or subsequent `RowSet` object, there may be an initial degradation in performance while the `JOIN` is being performed.

The following code fragment adds an additional `CachedRowSet` object. In this case, the match column (`EMP_ID`) is set when the `CachedRowSet` object is added to the `JoinRowSet` object.

        ResultSet rs3 = stmt.executeQuery("SELECT * FROM 401K_CONTRIB");
        CachedRowSet fourO1k = new CachedRowSetImpl();
        four01k.populate(rs3);
        jrs.addRowSet(four01k, 1);

The `JoinRowSet` object jrs now contains values from all three tables. The data in each row in four01k in which the value for the `EMP_ID` column matches a value for the `EMP_ID` column in jrs has been added to jrs.

## 4.0 `JoinRowSet` Methods

The `JoinRowSet` interface supplies several methods for adding `RowSet` objects and for getting information about the `JoinRowSet` object.

- Methods for adding one or more `RowSet` objects
  These methods allow an application to add one `RowSet` object at a time or to add multiple `RowSet` objects at one time. In either case, the methods may specify the match column for each `RowSet` object being added.
- Methods for getting information
  One method retrieves the `RowSet` objects in the `JoinRowSet` object, and another method retrieves the `RowSet` names. A third method retrieves either the SQL `WHERE` clause used behind the scenes to form the `JOIN` or a text description of what the `WHERE` clause does.
- Methods related to the type of `JOIN`
  One method sets the `JOIN` type, and five methods find out whether the `JoinRowSet` object supports a given type.
- A method to make a separate copy of the `JoinRowSet` object
  This method creates a copy that can be persisted to the data source.

Since:
  1.5

## Field Summary

Fields
Modifier and Type
Field
Description
`static final int`
`CROSS_JOIN`
An ANSI-style `JOIN` providing a cross product of two tables
`static final int`
`FULL_JOIN`
An ANSI-style `JOIN` providing a full JOIN.
`static final int`
`INNER_JOIN`
An ANSI-style `JOIN` providing a inner join between two tables.
`static final int`
`LEFT_OUTER_JOIN`
An ANSI-style `JOIN` providing a left outer join between two tables.
`static final int`
`RIGHT_OUTER_JOIN`
An ANSI-style `JOIN` providing a right outer join between two tables.

### Fields declared in interface CachedRowSet

`COMMIT_ON_ACCEPT_CHANGES`

### Fields declared in interface ResultSet

`CLOSE_CURSORS_AT_COMMIT, CONCUR_READ_ONLY, CONCUR_UPDATABLE, FETCH_FORWARD, FETCH_REVERSE, FETCH_UNKNOWN, HOLD_CURSORS_OVER_COMMIT, TYPE_FORWARD_ONLY, TYPE_SCROLL_INSENSITIVE, TYPE_SCROLL_SENSITIVE`

### Fields declared in interface WebRowSet

`PUBLIC_XML_SCHEMA, SCHEMA_SYSTEM_ID`

## Method Summary

Modifier and Type
Method
Description
`void`
`addRowSet(RowSet[] rowset, int[] columnIdx)`
Adds one or more `RowSet` objects contained in the given array of `RowSet` objects to this `JoinRowSet` object and sets the match column for each of the `RowSet` objects to the match columns in the given array of column indexes.
`void`
`addRowSet(RowSet[] rowset, String[] columnName)`
Adds one or more `RowSet` objects contained in the given array of `RowSet` objects to this `JoinRowSet` object and sets the match column for each of the `RowSet` objects to the match columns in the given array of column names.
`void`
`addRowSet(Joinable rowset)`
Adds the given `RowSet` object to this `JoinRowSet` object.
`void`
`addRowSet(RowSet rowset, int columnIdx)`
Adds the given `RowSet` object to this `JoinRowSet` object and sets the designated column as the match column for the `RowSet` object.
`void`
`addRowSet(RowSet rowset, String columnName)`
Adds rowset to this `JoinRowSet` object and sets the designated column as the match column.
`int`
`getJoinType()`
Returns a `int` describing the set SQL `JOIN` type governing this JoinRowSet instance.
`String[]`
`getRowSetNames()`
Returns a `String` array containing the names of the `RowSet` objects added to this `JoinRowSet` object.
`Collection<?>`
`getRowSets()`
Returns a `Collection` object containing the `RowSet` objects that have been added to this `JoinRowSet` object.
`String`
`getWhereClause()`
Return a SQL-like description of the WHERE clause being used in a JoinRowSet object.
`void`
`setJoinType(int joinType)`
Allow the application to adjust the type of `JOIN` imposed on tables contained within the JoinRowSet object instance.
`boolean`
`supportsCrossJoin()`
Indicates if CROSS_JOIN is supported by a JoinRowSet implementation
`boolean`
`supportsFullJoin()`
Indicates if FULL_JOIN is supported by a JoinRowSet implementation
`boolean`
`supportsInnerJoin()`
Indicates if INNER_JOIN is supported by a JoinRowSet implementation
`boolean`
`supportsLeftOuterJoin()`
Indicates if LEFT_OUTER_JOIN is supported by a JoinRowSet implementation
`boolean`
`supportsRightOuterJoin()`
Indicates if RIGHT_OUTER_JOIN is supported by a JoinRowSet implementation
`CachedRowSet`
`toCachedRowSet()`
Creates a new `CachedRowSet` object containing the data in this `JoinRowSet` object, which can be saved to a data source using the `SyncProvider` object for the `CachedRowSet` object.

### Methods declared in interface CachedRowSet

`acceptChanges, acceptChanges, columnUpdated, columnUpdated, commit, createCopy, createCopyNoConstraints, createCopySchema, createShared, execute, getKeyColumns, getOriginal, getOriginalRow, getPageSize, getRowSetWarnings, getShowDeleted, getSyncProvider, getTableName, nextPage, populate, populate, previousPage, release, restoreOriginal, rollback, rollback, rowSetPopulated, setKeyColumns, setMetaData, setOriginalRow, setPageSize, setShowDeleted, setSyncProvider, setTableName, size, toCollection, toCollection, toCollection, undoDelete, undoInsert, undoUpdate`

### Methods declared in interface Joinable

`getMatchColumnIndexes, getMatchColumnNames, setMatchColumn, setMatchColumn, setMatchColumn, setMatchColumn, unsetMatchColumn, unsetMatchColumn, unsetMatchColumn, unsetMatchColumn`

### Methods declared in interface ResultSet

`absolute, afterLast, beforeFirst, cancelRowUpdates, clearWarnings, close, deleteRow, findColumn, first, getArray, getArray, getAsciiStream, getAsciiStream, getBigDecimal, getBigDecimal, getBigDecimal, getBigDecimal, getBinaryStream, getBinaryStream, getBlob, getBlob, getBoolean, getBoolean, getByte, getByte, getBytes, getBytes, getCharacterStream, getCharacterStream, getClob, getClob, getConcurrency, getCursorName, getDate, getDate, getDate, getDate, getDouble, getDouble, getFetchDirection, getFetchSize, getFloat, getFloat, getHoldability, getInt, getInt, getLong, getLong, getMetaData, getNCharacterStream, getNCharacterStream, getNClob, getNClob, getNString, getNString, getObject, getObject, getObject, getObject, getObject, getObject, getRef, getRef, getRow, getRowId, getRowId, getShort, getShort, getSQLXML, getSQLXML, getStatement, getString, getString, getTime, getTime, getTime, getTime, getTimestamp, getTimestamp, getTimestamp, getTimestamp, getType, getUnicodeStream, getUnicodeStream, getURL, getURL, getWarnings, insertRow, isAfterLast, isBeforeFirst, isClosed, isFirst, isLast, last, moveToCurrentRow, moveToInsertRow, next, previous, refreshRow, relative, rowDeleted, rowInserted, rowUpdated, setFetchDirection, setFetchSize, updateArray, updateArray, updateAsciiStream, updateAsciiStream, updateAsciiStream, updateAsciiStream, updateAsciiStream, updateAsciiStream, updateBigDecimal, updateBigDecimal, updateBinaryStream, updateBinaryStream, updateBinaryStream, updateBinaryStream, updateBinaryStream, updateBinaryStream, updateBlob, updateBlob, updateBlob, updateBlob, updateBlob, updateBlob, updateBoolean, updateBoolean, updateByte, updateByte, updateBytes, updateBytes, updateCharacterStream, updateCharacterStream, updateCharacterStream, updateCharacterStream, updateCharacterStream, updateCharacterStream, updateClob, updateClob, updateClob, updateClob, updateClob, updateClob, updateDate, updateDate, updateDouble, updateDouble, updateFloat, updateFloat, updateInt, updateInt, updateLong, updateLong, updateNCharacterStream, updateNCharacterStream, updateNCharacterStream, updateNCharacterStream, updateNClob, updateNClob, updateNClob, updateNClob, updateNClob, updateNClob, updateNString, updateNString, updateNull, updateNull, updateObject, updateObject, updateObject, updateObject, updateObject, updateObject, updateObject, updateObject, updateRef, updateRef, updateRow, updateRowId, updateRowId, updateShort, updateShort, updateSQLXML, updateSQLXML, updateString, updateString, updateTime, updateTime, updateTimestamp, updateTimestamp, wasNull`

### Methods declared in interface RowSet

`addRowSetListener, clearParameters, execute, getCommand, getDataSourceName, getEscapeProcessing, getMaxFieldSize, getMaxRows, getPassword, getQueryTimeout, getTransactionIsolation, getTypeMap, getUrl, getUsername, isReadOnly, removeRowSetListener, setArray, setAsciiStream, setAsciiStream, setAsciiStream, setAsciiStream, setBigDecimal, setBigDecimal, setBinaryStream, setBinaryStream, setBinaryStream, setBinaryStream, setBlob, setBlob, setBlob, setBlob, setBlob, setBlob, setBoolean, setBoolean, setByte, setByte, setBytes, setBytes, setCharacterStream, setCharacterStream, setCharacterStream, setCharacterStream, setClob, setClob, setClob, setClob, setClob, setClob, setCommand, setConcurrency, setDataSourceName, setDate, setDate, setDate, setDate, setDouble, setDouble, setEscapeProcessing, setFloat, setFloat, setInt, setInt, setLong, setLong, setMaxFieldSize, setMaxRows, setNCharacterStream, setNCharacterStream, setNCharacterStream, setNCharacterStream, setNClob, setNClob, setNClob, setNClob, setNClob, setNClob, setNString, setNString, setNull, setNull, setNull, setNull, setObject, setObject, setObject, setObject, setObject, setObject, setPassword, setQueryTimeout, setReadOnly, setRef, setRowId, setRowId, setShort, setShort, setSQLXML, setSQLXML, setString, setString, setTime, setTime, setTime, setTime, setTimestamp, setTimestamp, setTimestamp, setTimestamp, setTransactionIsolation, setType, setTypeMap, setUrl, setURL, setUsername`

### Methods declared in interface WebRowSet

`readXml, readXml, writeXml, writeXml, writeXml, writeXml`

### Methods declared in interface Wrapper

`isWrapperFor, unwrap`

## Field Details

### CROSS_JOIN

static final int CROSS_JOIN
An ANSI-style `JOIN` providing a cross product of two tables

See Also:
  - Constant Field Values

### INNER_JOIN

static final int INNER_JOIN
An ANSI-style `JOIN` providing a inner join between two tables. Any unmatched rows in either table of the join should be discarded.

See Also:
  - Constant Field Values

### LEFT_OUTER_JOIN

static final int LEFT_OUTER_JOIN
An ANSI-style `JOIN` providing a left outer join between two tables. In SQL, this is described where all records should be returned from the left side of the JOIN statement.

See Also:
  - Constant Field Values

### RIGHT_OUTER_JOIN

static final int RIGHT_OUTER_JOIN
An ANSI-style `JOIN` providing a right outer join between two tables. In SQL, this is described where all records from the table on the right side of the JOIN statement even if the table on the left has no matching record.

See Also:
  - Constant Field Values

### FULL_JOIN

static final int FULL_JOIN
An ANSI-style `JOIN` providing a full JOIN. Specifies that all rows from either table be returned regardless of matching records on the other table.

See Also:
  - Constant Field Values

## Method Details

### addRowSet

void addRowSet(Joinable rowset) throws SQLException
Adds the given `RowSet` object to this `JoinRowSet` object. If the `RowSet` object is the first to be added to this `JoinRowSet` object, it forms the basis of the `JOIN` relationship to be established.

This method should be used only when the given `RowSet` object already has a match column that was set with the `Joinable` method `setMatchColumn`.

Note: A `Joinable` object is any `RowSet` object that has implemented the `Joinable` interface.

Parameters:
  `rowset` - the `RowSet` object that is to be added to this `JoinRowSet` object; it must implement the `Joinable` interface and have a match column set
Throws:
  `SQLException` - if (1) an empty rowset is added to the to this `JoinRowSet` object, (2) a match column has not been set for rowset, or (3) rowset violates the active `JOIN`
See Also:
  - `Joinable.setMatchColumn(int)`

### addRowSet

void addRowSet(RowSet rowset, int columnIdx) throws SQLException
Adds the given `RowSet` object to this `JoinRowSet` object and sets the designated column as the match column for the `RowSet` object. If the `RowSet` object is the first to be added to this `JoinRowSet` object, it forms the basis of the `JOIN` relationship to be established.

This method should be used when RowSet does not already have a match column set.

Parameters:
  `rowset` - the `RowSet` object that is to be added to this `JoinRowSet` object; it may implement the `Joinable` interface
  `columnIdx` - an `int` that identifies the column to become the match column
Throws:
  `SQLException` - if (1) rowset is an empty rowset or (2) rowset violates the active `JOIN`
See Also:
  - `Joinable.unsetMatchColumn(int)`

### addRowSet

void addRowSet(RowSet rowset, String columnName) throws SQLException
Adds rowset to this `JoinRowSet` object and sets the designated column as the match column. If rowset is the first to be added to this `JoinRowSet` object, it forms the basis for the `JOIN` relationship to be established.

This method should be used when the given `RowSet` object does not already have a match column.

Parameters:
  `rowset` - the `RowSet` object that is to be added to this `JoinRowSet` object; it may implement the `Joinable` interface
  `columnName` - the `String` object giving the name of the column to be set as the match column
Throws:
  `SQLException` - if (1) rowset is an empty rowset or (2) the match column for rowset does not satisfy the conditions of the `JOIN`

### addRowSet

void addRowSet(RowSet[] rowset, int[] columnIdx) throws SQLException
Adds one or more `RowSet` objects contained in the given array of `RowSet` objects to this `JoinRowSet` object and sets the match column for each of the `RowSet` objects to the match columns in the given array of column indexes. The first element in columnIdx is set as the match column for the first `RowSet` object in rowset, the second element of columnIdx is set as the match column for the second element in rowset, and so on.

The first `RowSet` object added to this `JoinRowSet` object forms the basis for the `JOIN` relationship.

This method should be used when the given `RowSet` object does not already have a match column.

Parameters:
  `rowset` - an array of one or more `RowSet` objects to be added to the `JOIN`; it may implement the `Joinable` interface
  `columnIdx` - an array of `int` values indicating the index(es) of the columns to be set as the match columns for the `RowSet` objects in rowset
Throws:
  `SQLException` - if (1) an empty rowset is added to this `JoinRowSet` object, (2) a match column is not set for a `RowSet` object in rowset, or (3) a `RowSet` object being added violates the active `JOIN`

### addRowSet

void addRowSet(RowSet[] rowset, String[] columnName) throws SQLException
Adds one or more `RowSet` objects contained in the given array of `RowSet` objects to this `JoinRowSet` object and sets the match column for each of the `RowSet` objects to the match columns in the given array of column names. The first element in columnName is set as the match column for the first `RowSet` object in rowset, the second element of columnName is set as the match column for the second element in rowset, and so on.

The first `RowSet` object added to this `JoinRowSet` object forms the basis for the `JOIN` relationship.

This method should be used when the given `RowSet` object(s) does not already have a match column.

Parameters:
  `rowset` - an array of one or more `RowSet` objects to be added to the `JOIN`; it may implement the `Joinable` interface
  `columnName` - an array of `String` values indicating the names of the columns to be set as the match columns for the `RowSet` objects in rowset
Throws:
  `SQLException` - if (1) an empty rowset is added to this `JoinRowSet` object, (2) a match column is not set for a `RowSet` object in rowset, or (3) a `RowSet` object being added violates the active `JOIN`

### getRowSets

Collection<?> getRowSets() throws SQLException
Returns a `Collection` object containing the `RowSet` objects that have been added to this `JoinRowSet` object. This should return the 'n' number of RowSet contained within the `JOIN` and maintain any updates that have occurred while in this union.

Returns:
  a `Collection` object consisting of the `RowSet` objects added to this `JoinRowSet` object
Throws:
  `SQLException` - if an error occurs generating the `Collection` object to be returned

### getRowSetNames

String[] getRowSetNames() throws SQLException
Returns a `String` array containing the names of the `RowSet` objects added to this `JoinRowSet` object.

Returns:
  a `String` array of the names of the `RowSet` objects in this `JoinRowSet` object
Throws:
  `SQLException` - if an error occurs retrieving the names of the `RowSet` objects
See Also:
  - `CachedRowSet.setTableName(String)`

### toCachedRowSet

CachedRowSet toCachedRowSet() throws SQLException
Creates a new `CachedRowSet` object containing the data in this `JoinRowSet` object, which can be saved to a data source using the `SyncProvider` object for the `CachedRowSet` object.

If any updates or modifications have been applied to the JoinRowSet the CachedRowSet returned by the method will not be able to persist it's changes back to the originating rows and tables in the in the datasource. The CachedRowSet instance returned should not contain modification data and it should clear all properties of it's originating SQL statement. An application should reset the SQL statement using the `RowSet.setCommand` method.

In order to allow changes to be persisted back to the datasource to the originating tables, the `acceptChanges` method should be used and called on a JoinRowSet object instance. Implementations can leverage the internal data and update tracking in their implementations to interact with the SyncProvider to persist any changes.

Returns:
  a CachedRowSet containing the contents of the JoinRowSet
Throws:
  `SQLException` - if an error occurs assembling the CachedRowSet object
See Also:
  - `RowSet`
  - `CachedRowSet`
  - `SyncProvider`

### supportsCrossJoin

boolean supportsCrossJoin()
Indicates if CROSS_JOIN is supported by a JoinRowSet implementation

Returns:
  true if the CROSS_JOIN is supported; false otherwise

### supportsInnerJoin

boolean supportsInnerJoin()
Indicates if INNER_JOIN is supported by a JoinRowSet implementation

Returns:
  true is the INNER_JOIN is supported; false otherwise

### supportsLeftOuterJoin

boolean supportsLeftOuterJoin()
Indicates if LEFT_OUTER_JOIN is supported by a JoinRowSet implementation

Returns:
  true is the LEFT_OUTER_JOIN is supported; false otherwise

### supportsRightOuterJoin

boolean supportsRightOuterJoin()
Indicates if RIGHT_OUTER_JOIN is supported by a JoinRowSet implementation

Returns:
  true is the RIGHT_OUTER_JOIN is supported; false otherwise

### supportsFullJoin

boolean supportsFullJoin()
Indicates if FULL_JOIN is supported by a JoinRowSet implementation

Returns:
  true is the FULL_JOIN is supported; false otherwise

### setJoinType

void setJoinType(int joinType) throws SQLException
Allow the application to adjust the type of `JOIN` imposed on tables contained within the JoinRowSet object instance. Implementations should throw a SQLException if they do not support a given `JOIN` type.

Parameters:
  `joinType` - the standard JoinRowSet.XXX static field definition of a SQL `JOIN` to re-configure a JoinRowSet instance on the fly.
Throws:
  `SQLException` - if an unsupported `JOIN` type is set
See Also:
  - `getJoinType()`

### getWhereClause

String getWhereClause() throws SQLException
Return a SQL-like description of the WHERE clause being used in a JoinRowSet object. An implementation can describe the WHERE clause of the SQL `JOIN` by supplying a SQL strings description of `JOIN` or provide a textual description to assist applications using a `JoinRowSet`

Returns:
  whereClause a textual or SQL description of the logical WHERE clause used in the JoinRowSet instance
Throws:
  `SQLException` - if an error occurs in generating a representation of the WHERE clause.

### getJoinType

int getJoinType() throws SQLException
Returns a `int` describing the set SQL `JOIN` type governing this JoinRowSet instance. The returned type will be one of standard JoinRowSet types: `CROSS_JOIN`, `INNER_JOIN`, `LEFT_OUTER_JOIN`, `RIGHT_OUTER_JOIN` or `FULL_JOIN`.

Returns:
  joinType one of the standard JoinRowSet static field definitions of a SQL `JOIN`. `JoinRowSet.INNER_JOIN` is returned as the default `JOIN` type is no type has been explicitly set.
Throws:
  `SQLException` - if an error occurs determining the SQL `JOIN` type supported by the JoinRowSet instance.
See Also:
  - `setJoinType(int)`