mysql inserting unique value for either column1 or column2? - mysql

Question

I created a table with five columns:
userID,name,mobile_num,telphone_num,count
Either mobile or telephone number or both field must be filled in, and it should be unique. How can i create such a row in mysql?

Answer 1

CREATE TABLE information (
userID INT NOT NULL,
name varchar(255),
mobile_num INT UNIQUE,
telphone_num INT UNIQUE,
count INT,
PRIMARY KEY (userID)
)
the UNIQUE property forces the values to be unique, however that might be a problem for you because if two users GIVE you his mobile but DONT GIVE not their home phone, you won't be able to have two users with the value NULL, so I think the solution you are asking for might not be your best option.

Answer 2

The simplest way to do this is to enforce the requirement in the application code that inserts a row to the database.
This question suggests that it is not possible to enforce one of two columns not being null by a table constraint.
You could create an after insert trigger to check the requirements, but assuming the database is in the control of your application, just enforcing this requirement in the application makes most sense. The coding and error handling will be simpler.
It is not clear what you mean when you say the phone numbers "must be unique" but I would probably reconsider this requirement.
Two users could be at the same location (e.g. in the same household) and have the same phone number. So there could be duplicate phone numbers between users.
A user who uses their mobile number as their primary phone might enter the same phone number in both fields. I don't see any benefit in preventing this. Actually when this happens, you have more useful information than if you had prevented it. And trying to prevent it would probably result in a data entry interface that is confusing for the user.

Answer 3

CREATE TABLE information (
userID INT NOT NULL,
name varchar(255),
mobile_num INT,
telphone_num INT,
count INT,
PRIMARY KEY (userID,mobile_num,telephone_num)
)
Use the below query when face a situation to insert either any one number
insert into information(UserID,name,mobile_num,count)
values(3,'andrew',23443546,5);
or
insert into information(UserID,name,phone_num,count)
values(3,'andrew',23443546,5);
By default mysql will insert the value for other number as 0 in such situation,
So you can use 0 for the other number when you are going to insert only one number using
insert into information
values(3,'andrew',0,23443546,5);
insert into information
values(3,'andrew',23443546,0,5);

Answer 4

You can use a trigger:
DELIMITER //
CREATE TRIGGER checkPhoneNumbers
BEFORE INSERT ON tableName
FOR EACH ROW
BEGIN
SET #exists = (SELECT *
FROM tableName
WHERE mobile_num = NEW.mobile_num
|| mobile_num = NEW.telphone_num
|| telphone_num = NEW.telphone_num
|| telphone_num = NEW.telphone_num);
IF(#exists IS NOT NULL) THEN
SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = 'Telephone or mobile number already present!';
END IF;
END
//
DELIMITER ;
In this way you will have a db error if you insert a mobile or telephone number which is already present as mobile or telephone number