在oracle sql中解析字符串

SELECT SUBSTR('A,B,C,D', 1, INSTR('A,B,C,D', ',')-1) AS Substring1,
       SUBSTR('A,B,C,D', INSTR('A,B,C,D', ',')+1, INSTR('A,B,C,D', ',', 1, 2)-INSTR('A,B,C,D', ',')-1) AS Substring2,
       SUBSTR('A,B,C,D', INSTR('A,B,C,D', ',', 1, 2)+1, INSTR('A,B,C,D', ',', 1, 3)-INSTR('A,B,C,D', ',', 1, 2)-1) AS Substring3,
       SUBSTR('A,B,C,D', INSTR('A,B,C,D', ',', 1, 3)+1) AS Substring4
FROM dual;

SELECT REGEXP_SUBSTR('A1B2C3D4', '\d+', 1, LEVEL) AS ExtractedNumber
FROM dual
CONNECT BY REGEXP_SUBSTR('A1B2C3D4', '\d+', 1, LEVEL) IS NOT NULL;

SELECT UPPER('hello world') AS UppercaseString
FROM dual;