Create Random String Function and Populate Table in PostgreSQL

-- Step 1: Create a table 'employees' to store employee data with an auto-incrementing 'id' and 'name' as text.
CREATE TABLE employees(
    id serial primary key,  -- 'id' will automatically increment with each new row.
    name text  -- 'name' stores the employee's name as a text field.
);

-- Step 2: Create a function to generate random strings of a specified length.
CREATE OR REPLACE FUNCTION random_string(length integer) RETURNS text AS
$$
DECLARE
  -- Step 2.1: Define an array 'chars' containing characters (digits and letters) to choose from.
  chars text[] := '{0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z,a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z}';

  -- Step 2.2: Initialize a variable 'result' to store the generated random string.
  result text := '';

  -- Step 2.3: Variable 'i' will be used in the loop to generate each character of the string.
  i integer := 0;

  -- Step 2.4: 'length2' is calculated randomly, determining the length of the generated string.
  length2 integer := (SELECT trunc(random() * length + 1));
BEGIN
  -- Step 2.5: Raise an exception if the calculated string length is negative (should not happen).
  IF length2 < 0 THEN
    RAISE EXCEPTION 'Given length cannot be less than 0';
  END IF;

  -- Step 2.6: Loop through and generate the random string by appending random characters from the 'chars' array.
  FOR i IN 1..length2 LOOP
    result := result || chars[1 + random() * (array_length(chars, 1) - 1)];  -- Append a random character.
  END LOOP;

  -- Step 2.7: Return the generated random string.
  RETURN result;
END;
$$ LANGUAGE plpgsql;  -- Define the function using the PL/pgSQL procedural language.

-- Step 3: Insert 100000 random names into the 'employees' table.
INSERT INTO employees (name)
SELECT random_string(10)
FROM generate_series(1, 100000);