public AssignmentSpecification(AST eq,
    Queryable persister) 
{
		if ( eq.getType() != HqlSqlTokenTypes.EQ ) {
			throw new QueryException( "assignment in set-clause not associated with equals" );
		}
		this.eq = eq;
		this.factory = persister.getFactory();
		// Needed to bump this up to DotNode, because that is the only thing which currently
		// knows about the property-ref path in the correct format; it is either this, or
		// recurse over the DotNodes constructing the property path just like DotNode does
		// internally
		DotNode lhs = ( DotNode ) eq.getFirstChild();
		SqlNode rhs = ( SqlNode ) lhs.getNextSibling();
		validateLhs( lhs );
		final String propertyPath = lhs.getPropertyPath();
		Set temp = new HashSet();
		// yuck!
		if ( persister instanceof UnionSubclassEntityPersister ) {
			UnionSubclassEntityPersister usep = ( UnionSubclassEntityPersister ) persister;
			String[] tables = persister.getConstraintOrderedTableNameClosure();
			int size = tables.length;
			for ( int i = 0; i <  size; i ++ ) {
				temp.add( tables[i] );
			}
		}
		else {
			temp.add(
					persister.getSubclassTableName( persister.getSubclassPropertyTableNumber( propertyPath ) )
			);
		}
		this.tableNames = Collections.unmodifiableSet( temp );
		if (rhs==null) {
			hqlParameters = new ParameterSpecification[0];
		}
		else if ( isParam( rhs ) ) {
			hqlParameters = new ParameterSpecification[] { ( ( ParameterNode ) rhs ).getHqlParameterSpecification() };
		}
		else {
			List parameterList = ASTUtil.collectChildren(
			        rhs,
			        new ASTUtil.IncludePredicate() {
				        public boolean include(AST node) {
					        return isParam( node );
			            }
			        }
			);
			hqlParameters = new ParameterSpecification[ parameterList.size() ];
			Iterator itr = parameterList.iterator();
			int i = 0;
			while( itr.hasNext() ) {
				hqlParameters[i++] = ( ( ParameterNode ) itr.next() ).getHqlParameterSpecification();
			}
		}
}

 public boolean affectsTable(String tableName) 
{
		return this.tableNames.contains( tableName );
}

 public ParameterSpecification[] getParameters() 
{
		return hqlParameters;
}

 public String getSqlAssignmentFragment() 
{
		if ( sqlAssignmentString == null ) {
			try {
				SqlGenerator sqlGenerator = new SqlGenerator( factory );
				sqlGenerator.comparisonExpr( eq, false );  // false indicates to not generate parens around the assignment
				sqlAssignmentString = sqlGenerator.getSQL();
			}
			catch( Throwable t ) {
				throw new QueryException( "cannot interpret set-clause assignment" );
			}
		}
		return sqlAssignmentString;
}