如何通过 PostgreSQL 中的条件替换表中列中的值？

Question

I have a table named "building" in PostgreSQL. It has several columns and millions of rows. Each row has a unique id. It looks like

id        tags    height     building:levels    area
 1   apartment     58 m                  17      109
 2   apartment     null                null      111
 3        shed        7                   2    75sqm
 4  greenhouse       6m                   3      159
 5  industrial       16                 2;4      105
 6  commercial       27                   8      474

And I have another csv file with cleaned data for column height and building:levels . The csv looks like:

id    height     building:levels  
 1       58                  17   
 3        7                   2  
 4        6                   3  
 5       16                   4 
 6       27                   8 

I want to join the csv file back to the table on the server, and the final outcome might look like this:

id        tags    height     building:levels    area
 1   apartment       58                  17      109
 2   apartment     null                null      111
 3        shed        7                   2    75sqm
 4  greenhouse        6                   3      159
 5  industrial       16                   4      105
 6  commercial       27                   8      474

I want to replace the values in height and building:levels where the id are the same in the table and the csv file. I've tried to import data from csv but it didn't replace the values, only adding new rows. How can I achieve this?

Answer 1

You can import the csv file data in a temporary table first:

CREATE TEMPORARY TABLE IF NOT EXISTS building_temp LIKE building ;
COPY building_temp (id, height, "building:levels") FROM your_csv_file.csv WITH options_list ;

See the manual for building the options_list.

and then update the building table from that temporary table

UPDATE building AS b
   SET height = bt.height
     , "building:levels" = bt."building:levels"
  FROM building_temp AS bt
 WHERE b.id = bt.id