php的帮助文档,涉及到PHP的案例和基本语法,以及实际应用内容

												 				  Check whether key exists				  				 				 				 dba_delete				 dba_fetch				 DBA Functions				 PHP Manual								 				  dba_exists				  (PHP 4, PHP 5)dba_exists — Check whether key exists								 				 				  Description				  				   bool dba_exists				    ( string $key				   , resource $handle				   )								  				   dba_exists() checks whether the specified				   key				 exists in the database.				  				 								 				  Parameters				  				   								    								     key												     								      				       The key the check is performed for.				      				     								    								    								     handle												     								      				       The database handler, returned by dba_open() or				       dba_popen().				      				     								    								   								  				 								 				  Return Values				  				   Returns TRUE if the key exists, FALSE otherwise.				  				 								 				  See Also				  				   				    dba_delete()				    dba_fetch()				    dba_insert()				    dba_replace()				   				  				 												 dba_delete				 dba_fetch				 DBA Functions				 PHP Manual