--
-- CASE
-- Test the case statement
--
CREATE TABLE CASE_TBL (
  i integer,
  f double precision
);
CREATE TABLE CASE2_TBL (
  i integer,
  j integer
);
INSERT INTO CASE_TBL VALUES (1, 10.1);
INSERT INTO CASE_TBL VALUES (2, 20.2);
INSERT INTO CASE_TBL VALUES (3, -30.3);
INSERT INTO CASE_TBL VALUES (4, NULL);
INSERT INTO CASE2_TBL VALUES (1, -1);
INSERT INTO CASE2_TBL VALUES (2, -2);
INSERT INTO CASE2_TBL VALUES (3, -3);
INSERT INTO CASE2_TBL VALUES (2, -4);
INSERT INTO CASE2_TBL VALUES (1, NULL);
INSERT INTO CASE2_TBL VALUES (NULL, -6);
--
-- Simplest examples without tables
--
SELECT '3' AS "One",
  CASE
    WHEN 1 < 2 THEN 3
  END AS "Simple WHEN";
 One | Simple WHEN 
-----+-------------
 3   |           3
(1 row)

SELECT '<NULL>' AS "One",
  CASE
    WHEN 1 > 2 THEN 3
  END AS "Simple default";
  One   | Simple default 
--------+----------------
 <NULL> |               
(1 row)

SELECT '3' AS "One",
  CASE
    WHEN 1 < 2 THEN 3
    ELSE 4
  END AS "Simple ELSE";
 One | Simple ELSE 
-----+-------------
 3   |           3
(1 row)

SELECT '4' AS "One",
  CASE
    WHEN 1 > 2 THEN 3
    ELSE 4
  END AS "ELSE default";
 One | ELSE default 
-----+--------------
 4   |            4
(1 row)

SELECT '6' AS "One",
  CASE
    WHEN 1 > 2 THEN 3
    WHEN 4 < 5 THEN 6
    ELSE 7
  END AS "Two WHEN with default";
 One | Two WHEN with default 
-----+-----------------------
 6   |                     6
(1 row)

SELECT '7' AS "None",
   CASE WHEN random() < 0 THEN 1
   END AS "NULL on no matches";
 None | NULL on no matches 
------+--------------------
 7    |                   
(1 row)

-- Constant-expression folding shouldn't evaluate unreachable subexpressions
SELECT CASE WHEN 1=0 THEN 1/0 WHEN 1=1 THEN 1 ELSE 2/0 END;
 case 
------
    1
(1 row)

SELECT CASE 1 WHEN 0 THEN 1/0 WHEN 1 THEN 1 ELSE 2/0 END;
 case 
------
    1
(1 row)

-- However we do not currently suppress folding of potentially
-- reachable subexpressions
SELECT CASE WHEN i > 100 THEN 1/0 ELSE 0 END FROM case_tbl;
ERROR:  division by zero
-- Test for cases involving untyped literals in test expression
SELECT CASE 'a' WHEN 'a' THEN 1 ELSE 2 END;
 case 
------
    1
(1 row)

--
-- Examples of targets involving tables
--
SELECT
  CASE
    WHEN i >= 3 THEN i
  END AS ">= 3 or Null"
  FROM CASE_TBL;
 >= 3 or Null 
--------------
             
             
            3
            4
(4 rows)

SELECT
  CASE WHEN i >= 3 THEN (i + i)
       ELSE i
  END AS "Simplest Math"
  FROM CASE_TBL;
 Simplest Math 
---------------
             1
             2
             6
             8
(4 rows)

SELECT i AS "Value",
  CASE WHEN (i < 0) THEN 'small'
       WHEN (i = 0) THEN 'zero'
       WHEN (i = 1) THEN 'one'
       WHEN (i = 2) THEN 'two'
       ELSE 'big'
  END AS "Category"
  FROM CASE_TBL;
 Value | Category 
-------+----------
     1 | one
     2 | two
     3 | big
     4 | big
(4 rows)

SELECT
  CASE WHEN ((i < 0) or (i < 0)) THEN 'small'
       WHEN ((i = 0) or (i = 0)) THEN 'zero'
       WHEN ((i = 1) or (i = 1)) THEN 'one'
       WHEN ((i = 2) or (i = 2)) THEN 'two'
       ELSE 'big'
  END AS "Category"
  FROM CASE_TBL;
 Category 
----------
 one
 two
 big
 big
(4 rows)

--
-- Examples of qualifications involving tables
--
--
-- NULLIF() and COALESCE()
-- Shorthand forms for typical CASE constructs
--  defined in the SQL standard.
--
SELECT * FROM CASE_TBL WHERE COALESCE(f,i) = 4;
 i | f 
---+---
 4 |  
(1 row)

SELECT * FROM CASE_TBL WHERE NULLIF(f,i) = 2;
 i | f 
---+---
(0 rows)

SELECT COALESCE(a.f, b.i, b.j)
  FROM CASE_TBL a, CASE2_TBL b;
 coalesce 
----------
     10.1
     20.2
    -30.3
        1
     10.1
     20.2
    -30.3
        2
     10.1
     20.2
    -30.3
        3
     10.1
     20.2
    -30.3
        2
     10.1
     20.2
    -30.3
        1
     10.1
     20.2
    -30.3
       -6
(24 rows)

SELECT *
  FROM CASE_TBL a, CASE2_TBL b
  WHERE COALESCE(a.f, b.i, b.j) = 2;
 i | f | i | j  
---+---+---+----
 4 |   | 2 | -2
 4 |   | 2 | -4
(2 rows)

SELECT NULLIF(a.i,b.i) AS "NULLIF(a.i,b.i)",
  NULLIF(b.i, 4) AS "NULLIF(b.i,4)"
  FROM CASE_TBL a, CASE2_TBL b;
 NULLIF(a.i,b.i) | NULLIF(b.i,4) 
-----------------+---------------
                 |             1
               2 |             1
               3 |             1
               4 |             1
               1 |             2
                 |             2
               3 |             2
               4 |             2
               1 |             3
               2 |             3
                 |             3
               4 |             3
               1 |             2
                 |             2
               3 |             2
               4 |             2
                 |             1
               2 |             1
               3 |             1
               4 |             1
               1 |              
               2 |              
               3 |              
               4 |              
(24 rows)

SELECT *
  FROM CASE_TBL a, CASE2_TBL b
  WHERE COALESCE(f,b.i) = 2;
 i | f | i | j  
---+---+---+----
 4 |   | 2 | -2
 4 |   | 2 | -4
(2 rows)

-- Tests for constant subexpression simplification
explain (costs off)
SELECT * FROM CASE_TBL WHERE NULLIF(1, 2) = 2;
        QUERY PLAN        
--------------------------
 Result
   One-Time Filter: false
(2 rows)

explain (costs off)
SELECT * FROM CASE_TBL WHERE NULLIF(1, 1) IS NOT NULL;
        QUERY PLAN        
--------------------------
 Result
   One-Time Filter: false
(2 rows)

explain (costs off)
SELECT * FROM CASE_TBL WHERE NULLIF(1, null) = 2;
        QUERY PLAN        
--------------------------
 Result
   One-Time Filter: false
(2 rows)

--
-- Examples of updates involving tables
--
UPDATE CASE_TBL
  SET i = CASE WHEN i >= 3 THEN (- i)
                ELSE (2 * i) END;
SELECT * FROM CASE_TBL;
 i  |   f   
----+-------
  2 |  10.1
  4 |  20.2
 -3 | -30.3
 -4 |      
(4 rows)

UPDATE CASE_TBL
  SET i = CASE WHEN i >= 2 THEN (2 * i)
                ELSE (3 * i) END;
SELECT * FROM CASE_TBL;
  i  |   f   
-----+-------
   4 |  10.1
   8 |  20.2
  -9 | -30.3
 -12 |      
(4 rows)

UPDATE CASE_TBL
  SET i = CASE WHEN b.i >= 2 THEN (2 * j)
                ELSE (3 * j) END
  FROM CASE2_TBL b
  WHERE j = -CASE_TBL.i;
SELECT * FROM CASE_TBL;
  i  |   f   
-----+-------
   8 |  20.2
  -9 | -30.3
 -12 |      
  -8 |  10.1
(4 rows)

--
-- Nested CASE expressions
--
-- This test exercises a bug caused by aliasing econtext->caseValue_isNull
-- with the isNull argument of the inner CASE's CaseExpr evaluation.  After
-- evaluating the vol(null) expression in the inner CASE's second WHEN-clause,
-- the isNull flag for the case test value incorrectly became true, causing
-- the third WHEN-clause not to match.  The volatile function calls are needed
-- to prevent constant-folding in the planner, which would hide the bug.
-- Wrap this in a single transaction so the transient '=' operator doesn't
-- cause problems in concurrent sessions
BEGIN;
CREATE FUNCTION vol(text) returns text as
  'begin return $1; end' language plpgsql volatile;
SELECT CASE
  (CASE vol('bar')
    WHEN 'foo' THEN 'it was foo!'
    WHEN vol(null) THEN 'null input'
    WHEN 'bar' THEN 'it was bar!' END
  )
  WHEN 'it was foo!' THEN 'foo recognized'
  WHEN 'it was bar!' THEN 'bar recognized'
  ELSE 'unrecognized' END;
      case      
----------------
 bar recognized
(1 row)

-- In this case, we can't inline the SQL function without confusing things.
CREATE DOMAIN foodomain AS text;
CREATE FUNCTION volfoo(text) returns foodomain as
  'begin return $1::foodomain; end' language plpgsql volatile;
CREATE FUNCTION inline_eq(foodomain, foodomain) returns boolean as
  'SELECT CASE $2::text WHEN $1::text THEN true ELSE false END' language sql;
CREATE OPERATOR = (procedure = inline_eq,
                   leftarg = foodomain, rightarg = foodomain);
SELECT CASE volfoo('bar') WHEN 'foo'::foodomain THEN 'is foo' ELSE 'is not foo' END;
    case    
------------
 is not foo
(1 row)

ROLLBACK;
-- Test multiple evaluation of a CASE arg that is a read/write object (#14472)
-- Wrap this in a single transaction so the transient '=' operator doesn't
-- cause problems in concurrent sessions
BEGIN;
CREATE DOMAIN arrdomain AS int[];
CREATE FUNCTION make_ad(int,int) returns arrdomain as
  'declare x arrdomain;
   begin
     x := array[$1,$2];
     return x;
   end' language plpgsql volatile;
CREATE FUNCTION ad_eq(arrdomain, arrdomain) returns boolean as
  'begin return array_eq($1, $2); end' language plpgsql;
CREATE OPERATOR = (procedure = ad_eq,
                   leftarg = arrdomain, rightarg = arrdomain);
SELECT CASE make_ad(1,2)
  WHEN array[2,4]::arrdomain THEN 'wrong'
  WHEN array[2,5]::arrdomain THEN 'still wrong'
  WHEN array[1,2]::arrdomain THEN 'right'
  END;
 case  
-------
 right
(1 row)

ROLLBACK;
-- Test interaction of CASE with ArrayCoerceExpr (bug #15471)
BEGIN;
CREATE TYPE casetestenum AS ENUM ('e', 'f', 'g');
SELECT
  CASE 'foo'::text
    WHEN 'foo' THEN ARRAY['a', 'b', 'c', 'd'] || enum_range(NULL::casetestenum)::text[]
    ELSE ARRAY['x', 'y']
    END;
      array      
-----------------
 {a,b,c,d,e,f,g}
(1 row)

ROLLBACK;
--
-- Clean up
--
DROP TABLE CASE_TBL;
DROP TABLE CASE2_TBL;