Re: MySQL query

[Phillip Ward]

Quote

... in the end all data from column a has to added to column b and then column a should be null. How can we achieve it ?

Defined "added".

1. Value of b overwritten with value of a?
2. Value of a numerically added to the value of b?
3. Value of a concatenated to the value of b?
4. (Something else)

update table1 
set 
  column_b = column_a                      -- (case 1) 
, column_b = column_b + column_a           -- (case 2) 
, column_b = concat( column_b, column_a )  -- (case 3) 
, column_a = NULL                          -- (All Cases)
;

Of course, wrap this in a Transaction so you get everything (or nothing) done in one.

Regards, Phill W.