Q:

How to insert data as new column without primary keys to existing table in MySQL? 

I have existing table with number of columns. 
And I have list of strings with the same number of rows as number of rows in existing table.  I want to add new column to table and insert all the data quickly in that column.  What the best way to achieve this?  I can create new table with one column, insert data in that table and then merge somehow two tables or somehow insert data in first table.  I don't know names of columns in first table. 
Also my tables doesn't have primary keys. 
Is this possible? 

A:

You can use an alter table for add the new column  eg:
ALTER TABLE my_table
ADD my_column varchr(255);

If the table are someway related
Then use an update with join for update the added  colum with the value form the table my_table_with_values eg:
update  my_table 
join my_table_with_values on my_table.id = my_table_with_values.key_id
set my_column  = my_table_with_values.value
;

Otherwise if the two table have not relation between them  ..this mean that you have not a proper value to related  each others so the relation is only row num based  in this case 
you can server side  select from the two tables and loop over the first  table  
and update  each row of thw first table  with the corresponding (index based) value of the second 

