根据另一列的值将值插入新表的列中

Question

I have the following two tables:

table 1:
------------------
table1_id   name
------------------
1           tom
2           bob
3           anne



table 2:
------------------------------------
table2_id     table1_id       name
------------------------------------
1                             tom
2                             tom
3                             anne
4                             tom
5                             bob
6                             bob
7                             anne
8                             tom

I want to add the correct table1_id from table 1 into the table1_id column of table 2 based on the name. So that the first row is 1 - 1 - tom, ect.

How can this be executed in a MySQL query?

Thanks for help!

Answer 1

You can use join :

update table2 t2 join
       table1 t1
       on t2.name = t1.name
    set t2.table1_id = t1.table1_id;

For performance, you want an index on table1(name) . You also want to be sure that the column is not duplicated in table1 .