sql - Problem with MySql INSERT MAX()+1 -

I have a table with many users in that table, I have a column called user_id (INT), which I I want to pay a separate salary for User_id should start with 1

I have prepared a simple example:

  Showing all names ------------- - + - ---------------------- + | User_id | Name | + -------------- + ----------------------- + | 1 | Bob | | 1 | Marriage | | 2 | Bob | | 1 | John | | 3 | Bob | | 2 | Marriage | + -------------- + ----------------------- + Showing only where name = Bob + - - ----------- + ----------------------- + | User_id | Name | + -------------- + ----------------------- + | 1 | Bob | | 2 | Bob | | 3 | Bob | + -------------- + ----------------------- +  

The following questions will do this, but this only works if 'Bob' is already present in the table ...

  Log in user (user_id, name) SELECT (SELECT MAX ( User_id) +1 from users where name = 'bob'), 'bob';  

If Bob is not present (first entry) user_id 0 (zero) is set to the same problem. I need user_id to start with 1_ 0.

You can use something like this:

  Log in user (user_id, name) Select + 1 code (maximum number (user_id) from where user name = 'bob'), 0), 'bob';  

But such a query may have a running position. Make sure you are in the transaction and you lock the user table before running it. Otherwise you may end up with two Bobs with the same number.