MySQLi Articles - Page 315 of 388

As we know that MySQL supports foreign key for referential integrity but it does not support CHECK constraint. But we can emulate them by using triggers. It can be illustrated with the help of an example given below −ExampleSuppose we have a table named ‘car1’ which can have the fix syntax registration number like two letters, a dash, three digits, a dash, two letters as follows −mysql> Create table car1 (number char(9)); Query OK, 0 rows affected (0.32 sec) mysql> Insert into car1 values('AB-235-YZ'); Query OK, 1 row affected (0.10 sec)The above value is a valid one but what ... Read More

To illustrate it we are creating the following views −mysql> CREATE VIEW digits AS     -> SELECT 0 AS digit UNION ALL     -> SELECT 1 UNION ALL     -> SELECT 2 UNION ALL     -> SELECT 3 UNION ALL     -> SELECT 4 UNION ALL     -> SELECT 5 UNION ALL     -> SELECT 6 UNION ALL     -> SELECT 7 UNION ALL     -> SELECT 8 UNION ALL     -> SELECT 9; Query OK, 0 rows affected (0.08 sec) mysql> CREATE VIEW numbers AS SELECT ones.digit + ... Read More

We can use the syntax of MySQL JOIN for joining two tables into the 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.To illustrate it we are having the following example −ExampleIn this example, we are using two MySQL tables which have the following data −mysql> SELECT * FROM tcount_tbl; +-----------------+----------------+ | tutorial_author | tutorial_count | +-----------------+----------------+ | mahran          |      20        | | mahnaz          |     ... Read More

As we know that MySQL BETWEEN operator can be used to select values from some range of values. We can use BETWEEN operator along with views to select some range of values from the base table. To understand this concept we are using the base table ‘student_info’ having the following data −mysql> Select * from Student_info; +------+---------+------------+------------+ | id   | Name    | Address    | Subject    | +------+---------+------------+------------+ | 101  | YashPal | Amritsar   | History    | | 105  | Gaurav  | Chandigarh | Literature | | 125  | Raman   | Shimla     ... Read More

MySQL LIKE operator is used to select data based on pattern matching. Similarly, we can use LIKE operator with views to select particular data based on pattern matching from the base table. To understand this concept we are using the base table ‘student_info’ having the following data −mysql> Select * from Student_info; +------+---------+------------+------------+ | id   | Name    | Address    | Subject    | +------+---------+------------+------------+ | 101  | YashPal | Amritsar   | History    | | 105  | Gaurav  | Chandigarh | Literature | | 125  | Raman   | Shimla     | Computers  | | 130  | ... Read More

We can use GROUP BY to group values from a column, and, if we want, we can perform calculations on that column. You can use COUNT, SUM, AVG, etc., functions on the grouped column. To understand GROUP BY clause with views we are creating a view named ‘Info’ using the base table ‘Student_info’ having the following data − mysql> Select * from Student_info; +------+---------+------------+------------+ | id | Name | Address | Subject | +------+---------+------------+------------+ | 101 | YashPal | Amritsar | History ... Read More

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’.