How to create or insert data into a table that has no unique values using 2 different tables which also has no unique valus?

I have 3 tables.

1. Pin Code Master
2. Pin code temp
3. City temp

in pin code columns are entry id - number picode - number state - number district - number

pin code temp is same as master

city temp entry id - number city name - string state - number district - number state name - string

example data = pin code temp 32899, 343031, 29, 122

example data = city temp 6604, A Vellalapatti, 31, 666, Tamil Nadu

my problem is in some condition there are multiple entries available in city table with state and district.

now to fill my master table how to actually figure out the query to select the accurate data and fill my master table.

I tried to get the city name using state and district. which gave multiple results. but my master table must have only one result per state. I know i have to use FIU dabase to get the actual data but the same issue in their list. multiple cities with same state and district.

You state:

pin code temp is same as master

and ask

how to actually figure out the query to select the accurate data and fill my master table

Ignore the city table and use only the pin_code_temp data to populate pin_code_master.

For example, if you want to insert all the rows from pin_code_temp into pin_code_master that have new primary key values then:

INSERT INTO pin_code_master (id, picode, state, district)
SELECT id, picode, state, district
FROM   pin_code_temp t
WHERE  NOT EXISTS (
         SELECT 1
         FROM   pin_code_master m
         WHERE  t.id = m.id       -- Compare primary key columns
                                  -- If you have different primary/unique keys then
                                  -- change the filter and compare those columns.
       )

Which, for the sample data:

CREATE TABLE city (
  id        NUMERIC(10) PRIMARY KEY,
  city_name VARCHAR(50),
  state     NUMERIC(10),
  district  NUMERIC(10)
);

CREATE TABLE pin_code_master (
  id        NUMERIC(10) PRIMARY KEY,
  picode    NUMERIC(10),
  state     NUMERIC(10),
  district  NUMERIC(10)
);

CREATE TABLE pin_code_temp (
  id        NUMERIC(10) PRIMARY KEY,
  picode    NUMERIC(10),
  state     NUMERIC(10),
  district  NUMERIC(10)
);

INSERT INTO pin_code_master (id, picode, state, district)
SELECT 1, 1, 1, 1 FROM DUAL UNION ALL
SELECT 4, 3, 2, 2 FROM DUAL

INSERT INTO pin_code_temp (id, picode, state, district)
SELECT 1, 1, 1, 1 FROM DUAL UNION ALL
SELECT 2, 2, 1, 2 FROM DUAL UNION ALL
SELECT 3, 1, 2, 1 FROM DUAL UNION ALL
SELECT 4, 3, 2, 2 FROM DUAL

Then, after the INSERT, pin_code_master contains:

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