copy one table data from another

Question

table a contains:

ID: 1  Name: X 
    2        y
    3        z

table B contains:

ID:1    name:
   2         
   2

May i know how to copy the name from table a to table b and what will happen to to table b containing the same id.

Answer 1

Try to update table b.

Update b1
set b1.name=a1.name
from b b1
join a a1 on a1.id=b1.id

If table b is contain same id then same name updated.

Answer 2

Try to use UPDATE in following without joining tables:

UPDATE table_a a
SET Name = ( SELECT Name 
             FROM table_b b
             WHERE b.id = a.id )

Or you can do It by joining tables in following:

UPDATE a
SET a.Name = b.Name 
FROM table_a a
JOIN table_b b ON a.id = b.id

Answer 3

already id values are present in tableb so you have to use use update statement for copying name column values.

update tableb b set name= (select a.name from tablea a
    inner join
    tableb b
    on
    a.id=b.id)

Answer 4

This is for MysqL

Update b as b1 inner join a as a1 on a1.id=b1.id
set b1.name=a1.name