What does a “set+0” in a MySQL statement do?

The set+0 converts the set value to integer. Let us see an example by creating a table −

mysql> create table SetZeroDemo
   -> (
   -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,
   -> TechnicalSkills set('C','Spring Framework /Hibernate','Python','Django Framework','Core Java') NOT NULL
   -> );
Query OK, 0 rows affected (0.56 sec)

Insert some records in the table using insert command. The query is as follows −

mysql> insert into SetZeroDemo(TechnicalSkills)
-> values('C,Spring Framework /Hibernate,Python,Django Framework,Core Java');
Query OK, 1 row affected (0.20 sec)

Display all records from the table using select statement. The query is as follows −

mysql> select *from SetZeroDemo;

Here is the output −

+----+-----------------------------------------------------------------+
| Id | TechnicalSkills                                                 |
+----+-----------------------------------------------------------------+
| 1  | C,Spring Framework /Hibernate,Python,Django Framework,Core Java |
+----+-----------------------------------------------------------------+
1 row in set (0.00 sec)

Here is the query to set+0 in MySQL statement −

mysql> select TechnicalSkills+0 from SetZeroDemo;

The following is the output −

+-------------------+
| TechnicalSkills+0 |
+-------------------+
| 31                |
+-------------------+
1 row in set (0.00 sec)

Now, let us see how the result above is 31.

It starts from 0 till the insert value. In the above table there are 5 words that means it starts from power 0 to 4 (because there are 5 words) as shown below −

=2⁰+2¹+2²+2³+2⁴
=1+2+4+8+16
=15+16
=31

Karthikeya Boyini

Published on 01-Apr-2019 12:02:24

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