text: --
  -- Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
  --
  --
  -- CASE
  -- https://github.com/postgres/postgres/blob/REL_12_BETA2/src/test/regress/sql/case.sql
  -- Test the CASE statement
  --
  -- This test file was converted from pgSQL/case.sql.
  
  CREATE TABLE CASE_TBL (
    i integer,
    f double
  ) USING parquet;
  
  CREATE TABLE CASE2_TBL (
    i integer,
    j integer
  ) USING parquet;
  
  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 udf(1 < 2) THEN 3
    END AS `Simple WHEN`;
  
  SELECT '<NULL>' AS `One`,
    CASE
      WHEN 1 > 2 THEN udf(3)
    END AS `Simple default`;
  
  SELECT '3' AS `One`,
    CASE
      WHEN udf(1) < 2 THEN udf(3)
      ELSE udf(4)
    END AS `Simple ELSE`;
  
  SELECT udf('4') AS `One`,
    CASE
      WHEN 1 > 2 THEN 3
      ELSE 4
    END AS `ELSE default`;
  
  SELECT udf('6') AS `One`,
    CASE
      WHEN udf(1 > 2) THEN 3
      WHEN udf(4) < 5 THEN 6
      ELSE 7
    END AS `Two WHEN with default`;
  
  SELECT '7' AS `None`,
    CASE WHEN rand() < udf(0) THEN 1
    END AS `NULL on no matches`;
  
  -- Constant-expression folding shouldn't evaluate unreachable subexpressions
  SELECT CASE WHEN udf(1=0) THEN 1/0 WHEN 1=1 THEN 1 ELSE 2/0 END;
  SELECT CASE 1 WHEN 0 THEN 1/udf(0) WHEN 1 THEN 1 ELSE 2/0 END;
  
  -- [SPARK-27923] PostgreSQL throws an exception but Spark SQL is NULL
  -- However we do not currently suppress folding of potentially
  -- reachable subexpressions
  SELECT CASE WHEN i > 100 THEN udf(1/0) ELSE udf(0) END FROM case_tbl;
  
  -- Test for cases involving untyped literals in test expression
  SELECT CASE 'a' WHEN 'a' THEN udf(1) ELSE udf(2) END;
  
  --
  -- Examples of targets involving tables
  --
  
  SELECT '' AS `Five`,
    CASE
      WHEN i >= 3 THEN i
    END AS `>= 3 or Null`
    FROM CASE_TBL;
  
  SELECT '' AS `Five`,
    CASE WHEN i >= 3 THEN (i + i)
         ELSE i
    END AS `Simplest Math`
    FROM CASE_TBL;
  
  SELECT '' AS `Five`, 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;
  
  SELECT '' AS `Five`,
    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;
  
  --
  -- Examples of qualifications involving tables
  --
  
  --
  -- NULLIF() and COALESCE()
  -- Shorthand forms for typical CASE constructs
  --  defined in the SQL standard.
  --
  
  SELECT * FROM CASE_TBL WHERE udf(COALESCE(f,i)) = 4;
  
  SELECT * FROM CASE_TBL WHERE udf(NULLIF(f,i)) = 2;
  
  SELECT udf(COALESCE(a.f, b.i, b.j))
    FROM CASE_TBL a, CASE2_TBL b;
  
  SELECT *
     FROM CASE_TBL a, CASE2_TBL b
     WHERE udf(COALESCE(a.f, b.i, b.j)) = 2;
  
  SELECT udf('') AS Five, 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;
  
  SELECT '' AS `Two`, *
    FROM CASE_TBL a, CASE2_TBL b
    WHERE udf(COALESCE(f,b.i) = 2);
  
  -- We don't support update now.
  --
  -- Examples of updates involving tables
  --
  
  -- UPDATE CASE_TBL
  --   SET i = CASE WHEN i >= 3 THEN (- i)
  --                 ELSE (2 * i) END;
  
  -- SELECT * FROM CASE_TBL;
  
  -- UPDATE CASE_TBL
  --   SET i = CASE WHEN i >= 2 THEN (2 * i)
  --                 ELSE (3 * i) END;
  
  -- SELECT * FROM CASE_TBL;
  
  -- 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;
  
  --
  -- 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 udf('foo') THEN 'it was foo!'
      WHEN udf(vol(null)) THEN 'null input'
      WHEN 'bar' THEN 'it was bar!' END
    )
    WHEN udf('it was foo!') THEN 'foo recognized'
    WHEN 'it was bar!' THEN udf('bar recognized')
    ELSE 'unrecognized' END AS col;
  
  -- We don't support the features below:
  -- 1. CREATE DOMAIN ...
  -- 2. CREATE OPERATOR ...
  -- 3. CREATE TYPE ...
  
  -- 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;
  
  -- 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;
  
  -- 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;
  
  -- ROLLBACK;
  
  --
  -- Clean up
  --
  
  DROP TABLE CASE_TBL;
  DROP TABLE CASE2_TBL;
  