PHP

You really need to keep two issues apart: 1) the primary key is a logical construct - one of the candidate keys that uniquely and reliably identifies every row in your table. This can be anything, really - an INT, a GUID, a string - pick what makes most sense for your scenario.  2) the clustering key (the column or columns that define the "clustered index" on the table) - this is a physical storage-related thing, and here, a small, stable, ever-increasing data type is your best pick - INT or BIGINT as your default option. Another better explanation is below : A clustered index alters the way that the rows are stored. When you create a clustered index on a column (or a number of columns), SQL server sorts the table’s rows by that column(s). It is like a dictionary, where all words are sorted in alphabetical order in the entire book. A non-clustered index, on the other hand, does not alter the way the rows are stored in the table. It creates a completely different

1.Generators added   Support for generators has been added via the yield keyword. Generators provide an easy way to implement simple iterators without the overhead or complexity of implementing a class that implements the Iterator interface. A simple example that reimplements the range() function as a generator (at least for positive step values): <?php function  xrange ( $start ,  $limit ,  $step  =  1 ) {     for ( $i  =  $start ;  $i  <=  $limit ;  $i  +=  $step ) {          yield $i ;     } } echo  'Single digit odd numbers: ' ; /*  * Note that an array is never created or returned,  * which saves memory.  */ foreach ( xrange ( 1 ,  9 ,  2 ) as  $number ) {     echo  " $number  " ; } echo  "\n" ; ?> The above example will output: Single digit odd numbers: 1 3 5 7 9      2. finally keyword added try - catch blocks now support a finally block for code that should be