public override Expression VisitSqlSubStatementExpression (SqlSubStatementExpression expression)
{
ArgumentUtility.CheckNotNull ("expression", expression);
var sqlStatement = expression.SqlStatement;
var factory = new SqlPreparationSubStatementTableFactory (Stage, Context, _generator);
FromExpressionInfo = factory.CreateSqlTableForStatement (sqlStatement, _tableGenerator);
Assertion.DebugAssert (FromExpressionInfo.Value.WhereCondition == null);
return new SqlTableReferenceExpression (FromExpressionInfo.Value.SqlTable);
}