We can use the SQL UPDATE command with or without the WHERE CLAUSE in the PHP function – mysql_query(). This function will execute the SQL command in a similar way it is executed at the mysql> prompt. To illustrate it we are having the following example −ExampleIn this example, we are writing a PHP script to update the field named tutorial_title for a record having turorial_id as 3.

If we want to fetch conditional data from MySQL table then we can write WHERE clause in SQL statement and use it with a PHP script. While writing the PHP script we can use PHP function mysql_query(). This function is used to execute the SQL command and later another PHP function mysql_fetch_array() can be used to fetch all the selected data. This function returns a row as an associative array, a numeric array, or both. This function returns FALSE if there are no more rows. To illustrate it we are having the following example −ExampleIn this example we are writing ... Read More

MySQL views can be created by using a combination of logical operators like AND, OR, and NOT. It can be illustrated with the help of following examples −Examplemysql> Create or Replace View Info AS select ID, Name, Address , Subject FROM Student_info WHERE (Subject = 'Computers' AND ADDRESS = 'Delhi') OR (Subject = 'History' AND Address = 'Amritsar'); Query OK, 0 rows affected (0.11 sec) mysql> Select * from Info; +------+-------+---------+-----------+ | ID   | Name  | Address | Subject   | +------+-------+---------+-----------+ | 133  | Mohan | Delhi   | Computers | +------+-------+---------+-----------+ 1 row in set (0.00 sec)

As we know that PHP uses the msql_free_result() function to release cursor memory associated with MySQL result. To illustrate it we are having the following example −ExampleIn this example, we are writing the following PHP script that will release the memory after fetching the records from a table named ‘Tutorials_tbl’.

PHP uses mysql_free_result() function to release the cursor memory associated with MySQL result. It returns no value.SyntaxMysql_free_result(result);Followings are the parameters used in this function −Sr.NoParameter & Description1ResultRequired- Specifies a result set identifier returned by mysql_query(), mysql_store_result() or mysql_use_result()

If we want to create a view that takes the values from a table based on some particular condition(s) then we have to use WHERE clause while creating the view. The values depending upon the WHERE clause will be stored in view. The syntax of creating a MySQL view with WHERE clause can be as follows −SyntaxCreate View view_name AS Select_statements FROM table WHERE condition(s);ExampleTo illustrate the above concept, we are using the following data from table ‘Student_info’ −mysql> Select * from student_info; +------+---------+------------+------------+ | id   | Name    | Address    | Subject    | +------+---------+------------+------------+ | 101 ... Read More

MySQL views can be created by using logical operators like AND, OR, and NOT. It can be illustrated with the help of following examples −Views with AND operatorAs we know that logical AND operator compares two expressions and returns true if both the expressions are true. In the following example,  we are creating a view which has the conditions based on ‘AND’ operator.ExampleThe base table is Student_info having the following data −mysql> Select * from Student_info; +------+---------+------------+------------+ | id   | Name    | Address    | Subject    | +------+---------+------------+------------+ | 101  | YashPal | Amritsar   | History ... Read More

In case of updateable views, it is quite possible that we update the data that is not visible through the view because we create a view to revealing only the partial data of a table. Such kind of updates makes the view inconsistent. We can ensure the consistency of views by using WITH CHECK OPTION while creating or modifying the views. Although WITH CHECK OPTION clause is an optional part of CREATE VIEW statement but it is very useful to make views consistent.Basically, the WITH CHECK OPTION clause prevents us from updating or inserting the rows which are not visible ... Read More

To illustrate the making of MySQL view with subquery we are using the following data from the table ‘Cars’ −mysql> select * from cars; +------+--------------+---------+ | ID   | Name         | Price   | +------+--------------+---------+ |    1 | Nexa         | 750000  | |    2 | Maruti Swift | 450000  | |    3 | BMW          | 4450000 | |    4 | VOLVO        | 2250000 | |    5 | Alto         | 250000  | |    6 | Skoda ... Read More

As we know that we can modify a view by using ALTER VIEW statement but other than that we can also use CREATE OR REPLACE VIEW to modify an existing view. The concept is simple as MySQL simply modifies the view if it already exists otherwise a new view would be created. Following is the syntax of it −SyntaxCREATE OR REPLACE VIEW view_name AS Select_statements FROM table;Examplemysql> Create OR Replace VIEW Info AS Select Id, Name, Address, Subject from student_info WHERE Subject = 'Computers'; Query OK, 0 rows affected (0.46 sec)The above query will create or replace a view ‘Info’. ... Read More