需要使用同一数据库中另一个表中的数据填充一个表

Question

I am trying to populate one table from another table with mysql. First table is users and the second table is technicians .

Users contains : userID, surname, firstname, loginid, password, accesslevel .

Technicians contains : techID, tech_surname, tech_firstname, tech_loginid, tech_password, tech_accesslevel.

When I add a user, I want the technicians table to populate if accesslevel=tech and users.loginid is not equal to technicians.tech_loginid.

I have tried several things and the result is that either no record is added or all records in users where accesslevel=tech are added each time, giving me several duplicate records.

I tried this:

INSERT INTO technicians (techID, tech_surname, tech_firstname, tech_loginid, tech_passwrd, tech_accesslevel)
SELECT firstname, surname, loginid, accesslevel, passwrd, tech_loginid
FROM users, technicians
WHERE accesslevel='tech' AND 'loginid!=tech_loginid'

It doesn't work and if I remove the AND statement from the WHERE clause it pushes all the records each time a new user is added with accesslevel=tech.

What am I doing wrong? I've searched for hours for an answer.

Cheers

Answer 1

I think you're trying to insert those technicians that already do not exist in that table so a query would be something like this

INSERT INTO technicians  (techID, tech_surname, tech_firstname, tech_loginid, tech_passwrd, tech_accesslevel) 
SELECT loginid, surname, firstname, tech_loginid, passwrd, accesslevel 
FROM users 
LEFT OUTER JOIN technicians ON loginid = tech_loginid
WHERE accesslevel='tech' and tech_loginid IS null

Answer 2

You could try

    INSERT INTO technicians 
(techID, tech_surname, tech_firstname, tech_loginid, tech_passwrd, tech_accesslevel) 
    SELECT 
GetTechId(),surname, firstname, loginid , passwrd, accesslevel  FROM users u
    WHERE
NOT EXISTS (select 1 from technicians t where t.loginid=u.loginid) and 
u.accesslevel='tech'.