Database Articles - Page 606 of 671

Suppose currently we are using a database named ‘query’ and it is having the following tables in it −mysql> Show tables in query; +-----------------+ | Tables_in_query | +-----------------+ | student_detail  | | student_info    | +-----------------+ 2 rows in set (0.00 sec)Now, following is a stored procedure, which will accept the name of the database as its parameter and give us the list of tables with detailed information −mysql> DELIMITER// mysql> CREATE procedure tb_list(db_name varchar(40))    -> BEGIN    -> SET @z := CONCAT('Select * from information_schema.tables WHERE table_schema = ', '\'', db_name, '\'');    -> Prepare stmt from @z; ... Read More

Suppose currently we are using a database named ‘query’ and it is having the following tables in it −mysql> Show tables in query; +-----------------+ | Tables_in_query | +-----------------+ | student_detail  | | student_info    | +-----------------+ 2 rows in set (0.00 sec)Now, following is a stored procedure, which will give us the list of tables with detailed information −mysql> DELIMITER// mysql> CREATE procedure tablelist()    -> BEGIN    -> Select * from Information_schema.tables WHERE table_schema = 'query';    -> END // Query OK, 0 rows affected (0.06 sec) mysql> DELIMITER; mysql> CALL tablelist()\G *************************** 1. row ***************************   ... Read More

MySQL REVERSE() function can be used to reverse a string. Following example will demonstrate it −mysql> Select REVERSE('Tutorialspoint'); +---------------------------+ | REVERSE('Tutorialspoint') | +---------------------------+ | tniopslairotuT            | +---------------------------+ 1 row in set (0.00 sec) mysql> Select Reverse('10-11-12'); +---------------------+ | Reverse('10-11-12') | +---------------------+ | 21-11-01            | +---------------------+ 1 row in set (0.00 sec)

We can use INTERVAL() function with a column of a table by providing the first argument as the name of the column. In this case, al the values in that column would be compared with the values given as the other arguments of INTERVAL() function and on that basis of comparison, the result set is provided. To understand it, the data from the employee table is used which is as follows −mysql> Select* from employee568; +----+--------+--------+ | ID | Name   | Salary | +----+--------+--------+ | 1  | Gaurav | 50000  | | 2  | Rahul  | 20000  | | ... Read More

In this case, MySQL INTERVAL() function returns the index number of the last number in argument list plus 1. In other words, the last index number in the list plus 1 would be returned by this function. Following example will demonstrate it −mysql> Select INTERVAL(50,20,32,38,40); +--------------------------+ | INTERVAL(50,20,32,38,40) | +--------------------------+ | 4                        | +--------------------------+ 1 row in set (0.00 sec)

Actually, INTERVAL() function uses the binary search for searching the bigger number than the number at first argument. So, that is why if we want INTERVAL() function to work efficiently the list of numbers would be in ascending order. Following is a good way to use INTERVAL() function −mysql> Select INTERVAL(50,20,32,38,40,50,55);

MySQL returns -1 as output if the first argument of INTERVAL() function is NULL. Following example will demonstrate it −mysql> Select INTERVAL(NULL, 20, 32, 38, 40, 50, 55); +--------------------------------------+ | INTERVAL(NULL, 20, 32, 38, 40, 50, 55)     | +--------------------------------------+ | -1                                   | +--------------------------------------+ 1 row in set (0.00 sec)It will return -1 even if any of the other arguments is NULL along with the first argument.mysql> Select INTERVAL(NULL, 20, 32, NULL, 40, 50, NULL); +--------------------------------------+ | INTERVAL(NULL, 20, 32, NULL, 40, 50, NULL) ... Read More

MySQL INTERVAL() function returns the index value of the argument which is greater than the first argument. Syntax INTERVAL(N,N1,N2,N3,…) Here, this function will compare 1st argument i.e. N with the other arguments i.e. N1, N2, N3 and so on. All the arguments are treated as integers. It returns the output as follows − If N

Suppose if we want to see all the records of a table by passing its name as the parameter of a stored procedure then following example will create a procedure named ‘details’ which accepts the name of the table as its parameter −mysql> DELIMITER // mysql> Create procedure details(tab_name Varchar(40))    -> BEGIN    -> SET @t:= CONCAT('Select * from', ' ', tab_name);    -> Prepare stmt FROM @t;    -> EXECUTE stmt;    -> END // Query OK, 0 rows affected (0.00 sec)Now invoke this procedure by giving the name of the table as its parameter and it will ... Read More

Following example will create a procedure named ‘tabledetails’ which gives all the details of a particular table stored in database.Examplemysql> DELIMITER // mysql> Create Procedure tabledetails()    -> BEGIN    -> DESCRIBE Student_detail;    -> END // Query OK, 0 rows affected (0.00 sec) mysql> DELIMITER ; mysql> CALL tabledetails; +-------------+-------------+------+-----+---------+-------+ | Field       | Type        | Null | Key | Default | Extra | +-------------+-------------+------+-----+---------+-------+ | Studentid   | int(11)     | NO   | PRI | NULL    |       | | StudentName | varchar(20) | YES  |     | NULL    |       | | address     | varchar(20) | YES  |     | NULL    |       | +-------------+-------------+------+-----+---------+-------+ 3 rows in set (0.01 sec) Query OK, 0 rows affected (0.04 sec)