mysql replace table data from another table when condition is met

Question

I am working on the database for a Wordpress Multisite install and need to copy multiple fields (but not all) from one table into another table, replace existing content and/or add row if they don't exist.

There are similar answers elsewhere but I can't seem to figure this out.

tables are sourcetable and targettable

columns are option_name and option_value

basically, if option_name field = condition1 is present in targettable copy option_value field from sourcetable and replace targettable option_value field, if not present then add it

would like to update/replace multiple fields with one query

REPLACE or UPDATE option_value_field in targettable with data 
from sourcetable value_field 
where name_field equals "condition1"

REPLACE or UPDATE option_value_field in targettable with data 
from sourcetable value_field 
where name_field equals "condition2"

REPLACE or UPDATE option_value_field in targettable with data 
from sourcetable value_field
where name_field equals "condition3" (add if does not exist)

thanks

Answer 1

Make option_name field unique, and use INSERT...ON DUPLICATE KEY UPDATE statement to insert/replace values in targettable -

INSERT INTO targettable
SELECT * FROM sourcetable
ON DUPLICATE KEY UPDATE option_value = VALUES(option_value)