===== SQL and PL/pgSQL =====

==== JSON ====
[[https://cdn.sanity.io/files/sczeoy4w/production/065818a8cd88cd048137368e5710ec35c0361185.pdf|| JSON Cheat Sheet]]

==== Arrays ====

Arrays can be displayed as ''ARRAY[1,2,3]'' or ''{1,2,3}''.\\

=== Operators ===
<code SQL>
SELECT 1 WHERE 'ian' = ANY(ARRAY['ian','bob']); --True
SELECT 1 WHERE 'ian' = ALL(ARRAY['ian','bob']); --False
-- Does each element appearing in the 2nd array equal some element of the 1st array
SELECT ARRAY[1,2,3] @> ARRAY[1,3];              --True
SELECT ARRAY[1,2,3] @> ARRAY[1,3,4];            --False
-- Does each element appearing in the 1st array equal some element of the 2nd array
SELECT ARRAY[1,3] <@ ARRAY[1,2,3];              --True
SELECT ARRAY[1,3,4] <@ ARRAY[1,2,3];            --False
-- Do the arrays have any elements in common.
SELECT ARRAY[1,2,3] && ARRAY[3,4];              --True
SELECT ARRAY[1,2,3] && ARRAY[4,5];              --False
</code>

=== Append / Prepend ===
<code SQL>
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]);
</code>

=== Replace / Remove ===
<code SQL>
SELECT array_replace(ARRAY[1,2,4], 4, 3);
SELECT array_remove(ARRAY[1,2,3,4], 4);
</code>

=== Concatenate ===
<code SQL>
SELECT ARRAY[1,2,3] || 4;
SELECT 0 || ARRAY[1,2,3];
SELECT array_cat(ARRAY[0], ARRAY[1,2.3]);
</code>

=== Length ===
<code SQL>
SELECT array_length(ARRAY[1,2,3], 1);
SELECT cardinality(ARRAY[1,2,3]);
</code>

=== Position ===
<code SQL>
SELECT array_position(ARRAY[1,2,3], 2);
SELECT array_positions(ARRAY[1,2,2,3], 2);
</code>

=== Conversion ===
<code SQL>
SELECT array_to_string(ARRAY[1,2,3], ',');         -- Returns 1 row (1,2,3)
SELECT unnest(ARRAY[1,2,3]);                       -- Returns 3 rows
SELECT generate_subscripts(ARRAY['A','B','C'], 1); -- Returns 3 rows

--Convert text column with comma separated values to array
ALTER TABLE name_basics ALTER primaryprofession TYPE text[] 
                        USING string_to_array(primaryprofession, ','); 
</code>

==== Templates ====

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

=== Procedures ===
<code>
CREATE [OR REPLACE] PROCEDURE prc_nme()
LANGUAGE plpgsql
AS $$
DECLARE
-- Variables
BEGIN
-- Body
END; $$
</code>

=== If Then Else ===
<code>
IF condition_1 THEN
  statement_1;
ELSIF condition_n THEN
  statement_n;
ELSE
  else-statement;
END IF;
</code>

=== Case ===
<code>
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;
</code>

=== Loop ===
<code>
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
</code>