Suggestions on how to convert my t-sql code to mysql

Question

I'm a T-SQL coder and I'm starting to code in MySQL Workbench. I'm trying to apply triggers and function in MySQL but am having difficulties with the syntax.

Basically my code below wants to use the StudentID (incrementing) as basis for my Studentnumber code having max value of 5 zero digits. liek this----> 13-00001 (where 13 is the last digit of the year and 1 is the StudentID value.) So if I insert 291 records, my last record will be 13-00291.

In T-SQL I have the following code:

create table Student
(   StudentID int identity not null primary key,
    Name varchar(100),
    StudentNumber varchar(10) 
)

create function StudentNumber (@id int) 
returns char(9) 
as 
begin 
return (SELECT SUBSTRING((CONVERT(VARCHAR(10),GETDATE(),112)),3,2)) + '-' + right('000000' + convert(varchar(10), @id), 6) 
end

create trigger Student_insert on Student 
after insert as 
update 
    Student 
set 
    Student.StudentNumber = dbo.StudentNumber(Student.StudentID) 
from 
    Student 
inner join 
    inserted on Student.StudentID= inserted.StudentID

When I started coding in MySQL creating tables is basic, but when I created my triggers and function, it seems there is a big difference with how mysql works. I've read that Identity's equivalent in MYSQL is AutoIncrement PK, but I've also read that when a trigger is fired, it can't get the value of my PK because the record hasnt been committed yet (or something along those lines) I've read that the only way to do the function I want in MySQL is to create a temp table which will store the ID or something. But I'd like to ask the opinion of others here if there's a way to recreate my function in MYSQL without having to resort to creating temp tables.

Thanks

Answer 1

If you want to use an auto_increment field for this in MySql you'll have to have a separate table for sequencing like this.

Your schema

CREATE TABLE student_seq(id INT AUTO_INCREMENT NOT NULL PRIMARY KEY)|

CREATE TABLE student
(   StudentID INT NOT NULL PRIMARY KEY,
    Name VARCHAR(100),
    StudentNumber VARCHAR(8) DEFAULT NULL
);

Function

CREATE FUNCTION student_number (id INT)
RETURNS VARCHAR(8) 
  RETURN CONCAT(DATE_FORMAT(CURDATE(), '%y'), '-', LPAD(id, 5, '0'));

Now the trigger

DELIMITER $$
CREATE TRIGGER tg_student_insert 
BEFORE INSERT ON Student
FOR EACH ROW 
BEGIN
  DECLARE nextid INT DEFAULT 0;
  INSERT INTO student_seq VALUES(NULL);
  SET nextid = LAST_INSERT_ID();
  SET NEW.studentid = nextid, NEW.studentnumber = student_number(nextid);
END$$
DELIMITER ;

Lets insert a new student

INSERT INTO student (studentid, name) VALUES(0, 'Jhon');

You'll get in student table

| STUDENTID | NAME | STUDENTNUMBER |
------------------------------------
|         1 | Jhon |      13-00001 |

Here is SQLFiddle demo.