Mysql – Difference in between MySQL affected num rows and num rows

MySQL

I am just newbie to the MySQL.I want to know what is the main differences in between mysql num rows and mysql affected num rows?Any example or references will be highly appreciable.

Best Answer

Here's mysql_num_rows:

int mysql_num_rows ( resource $result )

Retrieves the number of rows from a result set. This command is only valid for statements like SELECT or SHOW that return an actual result set. To retrieve the number of rows affected by a INSERT, UPDATE, REPLACE or DELETE query, use mysql_affected_rows().

And here's mysql_affected_rows:

int mysql_affected_rows ([ resource $link_identifier = NULL ] )

Get the number of affected rows by the last INSERT, UPDATE, REPLACE or DELETE query associated with link_identifier.

Notice that the input types are different: the first wants a result set, from which it counts the number of rows returned; the second wants a db handle. That makes sense, though, because when you INSERT (or UPDATE, DELETE, REPLACE) a row, you typically don't want a result set -- you just want to know if it succeeded or failed, or how many rows it updated/replaced/deleted.

Related Solutions

Mysql – Using Foreign Keys in database

No, you have not defined any Foreign key constraints.

The MySQL documentation page about FOREIGN KEY constraints has more details and possible options.

Here's an example for the invoices -> customers Foreign Key:

CREATE TABLE IF NOT EXISTS `nt_invoices` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `customer_id` int(11) NOT NULL,
  `owner_id` int(11) NOT NULL,
  `invoice_title` varchar(80) NOT NULL,
  `invoice_issue_date` date NOT NULL,
  `due_date` date NOT NULL,
  `description` text NOT NULL,
  `created_by` int(11) DEFAULT NULL,
  `updated_by` int(11) DEFAULT NULL,
  `created_at` datetime DEFAULT NULL,
  `updated_at` datetime DEFAULT NULL,
  PRIMARY KEY (`id`),

  KEY customer_id_index (customer_id),        --- index to be used by the FK

  CONSTRAINT customer_invoice_fk              --- the FK constraint's name
    FOREIGN KEY (customer_id)
      REFERENCES nt_customers(id)
      ON UPDATE CASCADE                       --- or other action
      ON DELETE RESTRICT                      --- here, too  

) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=1 ;

Mysql – Import and Export database in Mongo just like MySQL

If you look inside mongodb/bin folder (ls -l) You can find a couple of binaries.

The mongoDB has import and export tools.

If you're running mongod locally on the default port, you can just do:

$ ./mongodump

Example: Dumping Everything

$ ./mongodump --host prod.example.com

Example: Dumping a Single Collection

$ ./mongodump --db blog --collection posts

Others like

mongoexport, mongoimport, mongorestore, bsondump etc.

for more http://www.mongodb.org/display/DOCS/Import+Export+Tools

Best Answer

Related Solutions

Mysql – Using Foreign Keys in database

Mysql – Import and Export database in Mongo just like MySQL

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