php - Update one field so that the order value will be continuous -

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in table 1 field "ord" contains order of values particular group.

tbl_test , fields group,time,ord,name

sample entries

id       group time                      ord          name ---------------------------------------------------------------- 1        1     1340865990                1            john 2        1     1340865880                2            jos 3        1     1340867830                3            mery 4        1     1340867830                4            bill 5        1     1340867830                5            stiev 6        1     1340867830                6            tom 7        2     1340867830                1            test 8        3     1340867830                2            john

if remove set of values group 1 example removed "mery" , "tom" "ord" field must have updated order value remaining items 

id       group time                      ord          name ---------------------------------------------------------------- 1        1     1340865990                1            john 2        1     1340865880                2            jos 4        1     1340867830                3            bill 5        1     1340867830                4            stiev

the item removed may of order. remove item user give list of ids , group.

how can implement in mysql?

note :

to update ord when single entry deleted using following query:

set @a = 3; update tbl_test  set ord = 5,time = 1337690755  group = 1 , id = 6;

if order related time (or id) work.

set @order:=0; update tbl_test set ord=@order:=@order+1 group=1 order time, id

the answer above borrowed from: updating columns sequence number mysql

alternative method found from: mysql insert order number varchar field

set @order:=0; update  set ord=@order:=@order + 1 tbl_test order time, id

resetting auto_increment id might option if no ord column not in use.


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