PSQL query to insert the records from one table to another based on condition

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I have 2 Postgres tables with the following structure:


                              Table "public.tmp"
      Column       |          Type           | Collation | Nullable | Default 
-------------------+-------------------------+-----------+----------+---------
 MY_SL             | character varying(50)   |           |          | 
 Release           | character varying(50)   |           |          | 
 HOST              | character varying(50)   |           | not null | 
 UN NO.            | character varying(50)   |           |          | 
 STATUS            | character varying(50)   |           |          | 
 S_DATE            | character varying(50)   |           | not null | 

                                        Table "public.mo"
      Column       |          Type           | Collation | Nullable |                 Default                 
-------------------+-------------------------+-----------+----------+-----------------------------------------
 id                | integer                 |           | not null | nextval('mbss_output_id_seq'::regclass)
 HOST              | character varying(50)   |           | not null | 
 UN NO.            | character varying(50)   |           |          | 
 STATUS            | character varying(50)   |           |          | 
 S_DATE            | character varying(50)   |           | not null | 
 compliant_status  | character varying(50)   |           | not null |

Lets say I have data in the tmp table as below:

Table: tmp

 MY_SL | Release | HOST       |  UN NO.|  STATUS   |      S_DATE    
------------+-------------+-----------+----------------------+------------------
 2     | 1       | RhelTest   | 7:1:8  | COMPLIANT | 2020-08-26T15:16:48Z 
 12    | 1       | RhelTest   | 7:1:9  | COMPLIANT | 2020-08-26T15:16:48Z 
 22    | 2       | RhelTest   | 7:2:1  | COMPLIANT | 2020-08-26T15:16:48Z 
 4     | 1       | RhelTest   | 7:2:10 | NC        | 2020-08-26T15:16:48Z 
 11    | 2       | RhelTest   | 7:2:11 | NC        | 2020-08-26T15:16:48Z 
 1     | 3       | Demo1      | 7:2:11 | NC        | 2020-08-26T15:16:48Z 
 23    | 3       | Demo1      | 7:2:11 | NC        | 2020-08-26T15:16:48Z 
 333   | 3       | Demo2      | 7:2:11 | COMPLIANT | 2020-08-26T15:16:48Z

Now I want to write a psql INSERT INTO query which will copy the data from public.tmp to public.mo table and also perform below condition

When a Host has mix values in STATUS column, for eg if HOST: RhelTest

  • has 2 values in STATUS column as 'COMPLIANT' and 'NC' then the column compliant_status should have the value 'PARTIAL' for such rows
  • or if there is only one value like 'COMPLIANT' then the column compliant_status should have the value 'COMPLIANT' for such rows
  • or if there is only one value like 'NC' then the column compliant_status should have the value 'NON_COMPLIANT' for such rows

Finally Expected output in the public.mo table:

Table: public.mo

 id | HOST       |  UN NO.|  STATUS   |      S_DATE          | compliant_status 
------------+-------------+-----------+----------------------+------------------
 1  | RhelTest   | 7:1:8  | COMPLIANT | 2020-08-26T15:16:48Z | PARTIAL
 2  | RhelTest   | 7:1:9  | COMPLIANT | 2020-08-26T15:16:48Z | PARTIAL
 3  | RhelTest   | 7:2:1  | COMPLIANT | 2020-08-26T15:16:48Z | PARTIAL
 4  | RhelTest   | 7:2:10 | NC        | 2020-08-26T15:16:48Z | PARTIAL
 5  | RhelTest   | 7:2:11 | NC        | 2020-08-26T15:16:48Z | PARTIAL
 6  | Demo1      | 7:2:11 | NC        | 2020-08-26T15:16:48Z | NON_COMPLIANT
 7  | Demo1      | 7:2:11 | NC        | 2020-08-26T15:16:48Z | NON_COMPLIANT
 8  | Demo2      | 7:2:11 | COMPLIANT | 2020-08-26T15:16:48Z | COMPLIANT
sql-insert subquery case postgresql sql
1 Answers

You can use window functions and a case expression. Here is one way to do it, assuming that there are only two possible values for status, as shown in your data:

insert in mo (host, un_no, status, s_date, compliant_status)
select host, un_no, status, s_date,
    case 
        when min_host_status <> max_host_status then 'PARTIAL'
        when min_host_status = 'NC' then 'NON_COMPLIANT'
        else min_host_status
    end
from (
    select t.*,
        min(status) over(partition by host) min_host_status,
        max(status) over(partition by host) max_host_status
    from tmp t
) t

The idea is to compare the minimum and maximum values of status for each host. If there are different, then compliant_status is "PARTIAL". Else, we turn "NC" to "NON_COMPLIANT", and leave the other value ("COMPLIANT") as it is.

The subquery is not strictly necessary here, we could very well use the window functions directly in the outer query; I used it because it avoids repeating the same expressions again and again.

user_106767160
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