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 if...else condition in PHP script to prepare a query based on the NULL value. To illustrate it we are having the following example −ExampleIn this example, we are using the table named ‘tcount_tbl’ having the following data −mysql> SELECT * from tcount_tbl; +-----------------+----------------+ | tutorial_author | tutorial_count | +-----------------+----------------+ |      mahran     |       20       | |      mahnaz     |      NULL      | |       Jen       |      NULL      | |      Gill       |       20       | +-----------------+----------------+ 4 rows in set (0.00 sec)Now, the following is a PHP script that takes the value of ‘tutorial_count’ from outside and compares it with the value available in the field.

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

We can use the similar syntax of the ORDER BY clause 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 writing a PHP script that will return the result in descending order of the authors of the tutorial −

We can use the similar syntax of the WHERE...LIKE clause 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 if the WHERE...LIKE clause is used along with the SELECT command.But if the WHERE...LIKE clause is being used with the DELETE or UPDATE command, then no further PHP function call is required.To illustrate it we are having the following example −ExampleIn this example, we are writing a PHP script that will return all the records from the table named ‘tutorial_tbl’ ... 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 DELETE command with or without the WHERE CLAUSE into 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 − Example In this example, we are writing a PHP script to delete a record from MySQL table named ‘tutorial_tbl’ whose tutorial_id as 3.