Question

What is the best way to assign orders to mysql table rows? If I have rows 1 to 5 and I want to remove 4, how can I make 5 the new 4? If I make make 3 the new 1, I need to add 1 to each of the other rows. There could be 1 or 2 rows or a hundred.

Is there a simpler way than manually programming each contingency?

Thanks in advance.

additional:
I have an interface where I add packages for customers to see. They are automatically ordered ascending by id. I can reorder them by price, package name, or whatever, but I want to arbitrarily order them by my own preference from time to time.

Thanks again.

Answer 1

Assuming you have a unique order_column column in your database:

To add a new row at position x:

• Lock tables
• update all rows where position >= x and add 1
• Then insert the new row at position x
• Unlock tables

To swap positions x and y:

• UPDATE table SET x=(@temp:=x), x = y, y = @temp;

(source)

To remove a row at position x:

• Lock tables
• Remove row at position x
• update all rows where position > x and subtract 1
• Unlock tables

To display data:
Just ORDER BY by the order_column column.