SQL Where Combining values - mysql

Question

I have a database committee and one for users.
committee:
CREATE TABLE `committee` (
`com_ID` int(10) unsigned NOT NULL AUTO_INCREMENT,
`duties` varchar(64) COLLATE utf8_unicode_ci NOT NULL,
`duties_de` varchar(256) COLLATE utf8_unicode_ci NOT NULL,
`duties_fr` varchar(256) COLLATE utf8_unicode_ci NOT NULL,
`users_IDFS` int(10) unsigned DEFAULT NULL,
PRIMARY KEY (`com_ID`),
KEY `users_IDFS` (`users_IDFS`),
CONSTRAINT `committee_ibfk_1` FOREIGN KEY (`users_IDFS`) REFERENCES `users` (`ID`)
) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci
and users
CREATE TABLE `users` (
`ID` int(10) unsigned NOT NULL AUTO_INCREMENT,
`rank` tinyint(2) NOT NULL,
`name` varchar(32) NOT NULL,
`first_name` varchar(32) DEFAULT NULL,
`email` varchar(64) NOT NULL,
`passwd` varchar(128) NOT NULL,
`street` varchar(128) DEFAULT NULL,
`location` varchar(128) DEFAULT NULL,
`plz` varchar(8) DEFAULT NULL,
`m_number` varchar(32) DEFAULT NULL,
PRIMARY KEY (`ID`)
) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=utf8
Now my problem is that I want to update the user in the committee table, where the name e.g. "Hans Meier" == users.first_name and users.name
Is there a way I can split up the "Hans Meier" in an SQL statement or that I can combine users.first_name and users.name to a string and then compare it?

Answer 1

You can perform an update-join like
update committee c
join `users` u on c.name = u.name or c.name like CONCAT(u.first_name, '%')
set c.col = u.val;

Answer 2

The way to combine two strings into one is using the concat command.
http://dev.mysql.com/doc/refman/5.7/en/string-functions.html#function_concat
What you could do is, as you said, combine user.first_name and user.name and compare it.
select if('ab'=concat('a','b'),1,0);
What you should do is something like
select if('Hans Meier'= concat(user.first_name, ' ', user.name, <true clause>, <false clause>);
Don't forget the space or else it will fail.
select if('a b'=concat('a','b'),1,0);
The update sentence should look something like this
update committee
set user = <name of user>
where(user.name = concat(user.first_name, ' ', user.name);
Hope this helps!

Answer 3

You can use something like this
SUBSTRING('Hans Meier',0,LOCATE(" ", "Hans Meier"))
For first name
and SUBSTRING('Hans Meier',LOCATE(" ", "Hans Meier") + 1)
For last name

Answer 4

I am going to suggest that you fix your data model instead. If you are going to want to use the information from one table to update another, then it is best to store that information in the same way. You are asking to update using the full name but the only field I see for users to go into is an INT. In that case you would store the ID not the name.
Further it seems unlikely that a committee would have only one member. Likely you need a CommitteeMember table that stores the committeeID and the UserIDs of the members. It is a SQL antipattern to store multiple IDS in one column or to store the same committee record multiple times.
I see other problems with your model as well. Committees usually have names. I saw no field for that. When you add the name, add a unique index on this as well. If there are duties associated with a committee, then there should be a ComitteeDuty table because otherwise again you are going to have multiple records for the same committee or will have to concatenate in one field both of which are serious database design errors. You really need to read up on normalization before revisiting this design.