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SELECT ARRAY[1,2,3] || 4;
SELECT array_append(ARRAY[1,2,3], 4);

SELECT 0 || ARRAY[1,2,3];
SELECT array_prepend(0, ARRAY[1,2,3]);

SELECT array_replace(ARRAY[1,2,4], 4, 3);
SELECT array_remove(ARRAY[1,2,3,4], 4);

SELECT ARRAY[1,2,3] || 4;
SELECT 0 || ARRAY[1,2,3];
SELECT array_cat(ARRAY[0], ARRAY[1,2.3]);

SELECT array_length(ARRAY[1,2,3], 1);
SELECT cardinality(ARRAY[1,2,3]);

SELECT array_position(ARRAY[1,2,3], 2);
SELECT array_positions(ARRAY[1,2,2,3], 2);

SELECT array_to_string(ARRAY[1,2,3], ',');
SELECT unnest(ARRAY[1,2,3]);

CREATE [OR REPLACE] FUNCTION fnc_nme()
   RETURNS <return type> 
   LANGUAGE plpgsql
AS $$
DECLARE 
-- Variables
BEGIN
 -- Logic
END; $$

CREATE [OR REPLACE] PROCEDURE prc_nme()
LANGUAGE plpgsql
AS $$
DECLARE
-- Variables
BEGIN
-- Body
END; $$

IF condition_1 THEN
  statement_1;
ELSIF condition_n THEN
  statement_n;
ELSE
  else-statement;
END IF;

CASE RATE
  WHEN 'a' THEN variable = 1;
  WHEN 'b' THEN variable = 2;
  ELSE PRICE_SEGMENT = 0;
END CASE;

CASE 
  WHEN total > 200 THEN variable = 'PLATINUM' ;
  WHEN total > 100 THEN variable = 'GOLD' ;
  ELSE variable = 'SILVER' ;
END CASE;

LOOP
   -- Statements
   IF condition THEN
      EXIT;
   END IF;
END LOOP;

WHILE CONDITION LOOP
   -- Statements;
END LOOP;

FOR loop_counter in [ reverse ] FROM.. TO [ by step ] LOOP
    -- Statements
END LOOP