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Sunday, 17 March 2013

SQL: OR Command

In SQL, we have seen the use of AND command, to set multiple condition when performing a database transaction. But when we use AND, that means it's a mandatory condition. The transaction will provide output, only when all the conditions will be satisfied. But, what about an optional condition? Do SQL have any provision for that? The Answer is yes. SQL Do have command named OR to set optional condition.

Syntax: SELECT [column_name] FROM [table_name] WHERE [condition_1] OR [condition_2];

Here, output will come if [condition_1] OR [condition_2] OR both satisfied. That means, it is SELECT [column_name] FROM [table_name] WHERE [condition_1] OR [condition_2] OR both applied.


Example:

Again, we will use the same table, to see the usage of  OR command.
Table Name:

Employee Details ( employee_details)
Column Names:
Employee ID ( emp_id), 

Employee Name (emp_name), 
Employee Address (emp_address) and
Employee Role: (emp_role).

Table:  employee_details 


Now, using OR command, we will SELECT those tuple, WHERE emp_role is 'Developer' or 'Business Analyst'.
So, the query will be :

SELECT * FROM employee_details WHERE emp_role = 'Developer' OR emp_role = 'Business Analyst';

Result:











Sunday, 17 March 2013 by Anijit Sarkar · 0 Read more »

Friday, 1 March 2013

SQL: AND Command

In SQL, we have, seen that, we can add conditions by using WHERE command, during any SELECT, UPDATE or DELETE operation. Now, what about multiple conditions? For that, SQL provides to add multiple condition by using AND command. it can be used as many times as you want.

Syntax: SELECT [column_name] FROM [table_name] WHERE [condition_1] AND [condition_2];

[Note: AND means mandatory condition, that means, the operation has to always fulfill the criteria provied under AND block. ]

Example:

Again, use the same table, we will see the usage of  AND command.
Employee Details ( employee_details), which contains 
Employee ID ( emp_id), 

Employee Name (emp_name), 
Employee Address (emp_address) and
Employee Role: (emp_role).

Table:  employee_details 







Now, using AND command, we will SELECT those tuple, WHERE emp_role is 'Developer' and emp_address is 'Park Street, Kolkata'.
So, the query will be :

SELECT * FROM employee_details WHERE emp_role = 'Developer' AND emp_address = 'Park Street, Kolkata';

Result:




In this way, we can use multiple conditions on an RDBMS operation.

Friday, 1 March 2013 by Anijit Sarkar · 1 Read more »

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