SELECT a FROM x;
SELECT a FROM x;

SELECT "A" FROM "X";
SELECT "A" FROM "X";

SELECT a AS A FROM x;
SELECT a AS A FROM x;

SELECT * FROM x;
SELECT * FROM x;

SELECT A FROM x;
SELECT a FROM x;

SELECT a FROM X;
SELECT a FROM x;

SELECT A AS A FROM (SELECT a AS A FROM x);
SELECT a AS A FROM (SELECT a AS a FROM x);

SELECT a AS B FROM x ORDER BY B;
SELECT a AS B FROM x ORDER BY B;

SELECT A FROM x ORDER BY A;
SELECT a FROM x ORDER BY a;

SELECT A AS B FROM X GROUP BY A HAVING SUM(B) > 0;
SELECT a AS B FROM x GROUP BY a HAVING SUM(b) > 0;

SELECT A AS B, SUM(B) AS C FROM X GROUP BY A HAVING C > 0;
SELECT a AS B, SUM(b) AS C FROM x GROUP BY a HAVING C > 0;

SELECT A FROM X UNION SELECT A FROM X;
SELECT a FROM x UNION SELECT a FROM x;

SELECT A AS A FROM X UNION SELECT A AS A FROM X;
SELECT a AS A FROM x UNION SELECT a AS A FROM x;

(SELECT A AS A FROM X);
(SELECT a AS A FROM x);