Merge a specific table column from one database to another - mysql

Question

I have two SQL databases. One is an older backup of the other.
I would like to merge only 1 specific table from [user_database0] into [user_database1] using either ssh or inside phpMyAdmin.
That table that I want to restore from backup is called [prefix_table].
However, I don't want to restore all columns from that table [prefix_table], just the [comment] column.
One of my biggest concerns is that some of the rows from the [prefix_table] have been deleted and I DO NOT want to restore those deleted rows from the old database.
Here is an Example:
*- Merge table [prefix_table]from [user_database0]:
prefix_table
+---------------------------------------------------+
| id | name | comment | age | person_id |
+++++++++++++++++++++++++++++++++++++++++++++++++++++
| 1111 | name1 | old text 1 | 01 | 001 |
+------------+-------+------------+-----+-----------+
| 2222 | name2 | old text 2 | 02 | 002 |
+------------+-------+------------+-----+-----------+
| 3333 | name3 | old text 3 | 03 | 003 |
+------------+-------+------------+-----+-----------+
| 4444 | name4 | old text 4 | 04 | 004 |
+------------+-------+------------+-----+-----------+
*-Into table [prefix_table] in [user_database1] :
prefix_table
+-----------------------------------------------------+
| id | name | comment | age | person_id |
+++++++++++++++++++++++++++++++++++++++++++++++++++++++
| 1111 | namenew | new text 1 | 99 | 001 |
+------------+---------+------------+-----+-----------+
| 4444 | name4 | new text 4 | 04 | 004 |
+------------+---------+------------+-----+-----------+
| 5555 | name5 | text 1 | 05 | 005 |
+------------+---------+------------+-----+-----------+
| 6666 | name6 | text 2 | 06 | 006 |
+------------+---------+------------+-----+-----------+
*- Resulting database [user_database1]:
prefix_table
+-----------------------------------------------------+
| id | name | comment | age | person_id |
+++++++++++++++++++++++++++++++++++++++++++++++++++++++
| 1111 | namenew | old text 1 | 99 | 001 |
+------------+---------+------------+-----+-----------+
| 4444 | name4 | old text 4 | 04 | 004 |
+------------+---------+------------+-----+-----------+
| 5555 | name5 | text 1 | 05 | 005 |
+------------+---------+------------+-----+-----------+
| 6666 | name6 | text 2 | 06 | 006 |
+------------+---------+------------+-----+-----------+
So it basically has to check if the table [prefix_table] matches in both databases then overwrite the data in the [comment] column. Note that if other column data changes, it should leave it as is, only the [comment] should be updated.
In Summary (both databases are on same server in one phpMyAdmin account)
FROM: [user_database0].[prefix_table].[content]
TO: [user_database1].[prefix_table].[content]
IF: [id] column matches in both tables.
Here is a working version from the recommendations below:
UPDATE
[new_db_name].[table_name]
INNER JOIN
[old_db_name].[table_name]
ON
[new_db_name].[table_name].[column name] = [old_db_name].[table_name].[column name]
SET
[new_db_name].[table_name].[matching column name] = [new_db_name].[table_name].[matching column name]

Answer 1

The following will work. Here it is updating the new comment with the old comment for any matching IDs in both.
Edit: This should point you in the correct direction. I had your schema before, I misunderstood what you wrote - my bad.
UPDATE [new_table_name] SET comment = [old_table_name].onecomment
FROM [new_table_name]
INNER JOIN [old_table_name] ON [new_table_name].aboutme_id = [old_table_name].aboutme_id
Note: the above syntax is SQL Server because the question was at first erroneously tagged sql-server.