MySQL Articles - Page 324 of 355

In this case, SPACE() function would add white spaces depending upon the condition given in WHERE clause. The following example from student table will demonstrate it.Examplemysql> Select Id,Name,Space(5) from student WHERE Name='Harshit'; +------+---------+----------+ | Id   | Name    | Space(5) | +------+---------+----------+ | 15   | Harshit |          | +------+---------+----------+ 1 row in set (0.00 sec)

We can get the differences between the tables by unioning exclusion joins from 1st table to 2nd table and from 2nd table to 1st table. To understand it, we are taking the example of following two tables −mysql> Select * from value1; +-----+-----+ | i   | j   | +-----+-----+ |   1 |   1 | |   2 |   2 | +-----+-----+ 2 rows in set (0.00 sec) mysql> Select * from value2; +------+------+ | i    | j    | +------+------+ |    1 |   1  | |    3 |   3 ... Read More

Actually, INTERSECTION is just an inner join on all columns. We are taking a simple example of two tables, having the data as follows −mysql> Select * from value1; +------+------+ | i    | j    | +------+------+ | 1    | 1    | | 2    | 2    | +------+------+ 2 rows in set (0.00 sec) mysql> Select * from value2; +------+------+ | i    | j    | +------+------+ | 1    | 1    | | 3    | 3    | +------+------+ 2 rows in set (0.00 sec)Now, the following query will do the INTERSECTION between these tables −mysql> Select * from value1 join value2 using(i,j); +------+------+ | i    | j    | +------+------+ | 1    | 1    | +------+------+ 1 row in set (0.08 sec)

It can be understood with the help of an example in which two tables are having some values and we subtract the values with the help of LEFT JOIN. Here we are taking two tables having the following data −mysql> Select * from value_curdate; +----+----------+-------+ | Id | Product  | Price | +----+----------+-------+ | 1  | Notebook | 100   | | 2  | Pen      | 40    | | 3  | Pencil   | 65    | +----+----------+-------+ 3 rows in set (0.00 sec) mysql> Select * from value_prevdate; +----+-----------+-------+ | Id | Product   | ... Read More

Actually, sometimes we can avoid data-driven relationships in tables and we need to join them. It can be done with the help of CASE statement in the SELECT list to handle the joining possibilities. To understand it, we are taking the example of three data-driven tables namely ‘Student_Detail’ which have the following data −mysql> Select * from student_detail; +----+---------+ | Id | Name    | +----+---------+ | 1  | Harshit | | 2  | Rahul   | | 3  | Aarav   | +----+---------+ 3 rows in set (0.00 sec)Now, we have the three tables namely ‘Student_Harshit’, ‘Student_Rahul’, ‘Student_Aarav’ which ... Read More

In both the cases i.e. on not using ‘RIGHT’ or ‘LEFT’ keyword in the query, MySQL will return the result by taking it as INNER JOIN query. It is because the only difference between RIGHT, LEFT and INNER JOIN is the keyword of RIGHT or LEFT. To understand it, we are taking the example of two tables named tbl_1 and tbl_2 which are having following data −mysql> Select * from tbl_1; +----+--------+ | Id | Name   | +----+--------+ | 1  | Gaurav | | 2  | Rahul  | | 3  | Raman  | | 4  | Aarav  | +----+--------+ ... Read More

With the help of SOUNDS LIKE operator, MySQL search the similar sound values from the table. Syntax Expression1 SOUNDS LIKE Expression2 Here, both Expression1 and Expression2 will be compared based on their English pronunciation of sound. Example Following is an example from ‘student’ table which will match the two expressions based on the pronunciation of sound mysql> Select Id, Name, Address, Subject from student where name sounds like 'hrst'; +------+---------+---------+----------+ | Id | Name | Address | Subject | +------+---------+---------+----------+ | 15 | Harshit | Delhi | Commerce | +------+---------+---------+----------+ 1 row in set (0.00 sec)

We can distinguish between MySQL CROSS JOIN and INNER JOIN only on the basis of join-predicate i.e. the condition specified. While writing the query for INNER JOIN we need to specify the condition but in contrast, we do not need to specify the condition while writing a query for CROSS JOIN. To understand it, we are taking the example of two tables named tbl_1 and tbl_2 which are having following data −mysql> Select * from tbl_1; +----+--------+ | Id | Name | +----+--------+ | 1  | Gaurav | | 2  | Rahul  | | 3  | Raman  | | 4 ... Read More

MySQL has function name REVERSE() with the help of which we can reverse the string. But suppose if we want to reverse the string connected by dash then by using REVERSE() function will not give appropriate result as shown in the following example:mysql> Select REVERSE('AB-CD-EF'); +---------------------+ | REVERSE('AB-CD-EF') | +---------------------+ | FE-DC-BA            | +---------------------+ 1 row in set (0.00 sec)The appropriate result would be ‘EF-CD-AB’ and for getting such output we can use SUBSTRING_INDEX() function along with Instr() function. It is demonstrated as follows:mysql> Select CONCAT(SUBSTRING_INDEX('AB-CD-EF', '-', -1), '-', substr('AB-CD-EF', instr('AB-CD-EF', "-")+1, instr('AB-CD-EF', "-")), LEFT('AB-CD-EF', ... Read More

Writing inner joins with the help of comma operator is the most basic way to combine two tables. As we know that we can also write inner join by using keyword INNER JOIN or synonyms like JOIN. To form an inner join we need to specify a particular condition which is known as join-predicate and while writing inner joins using the comma operator, we use WHERE clause, the only way, to specify the join condition. To understand it, we are taking the example of two tables named tbl_1 and tbl_2 which are having following data:mysql> Select * from tbl_1; +----+--------+ ... Read More