ORACLE knowledge points (eight): ORACLE multi-line one-way transfer

Example SQL:

WITH TESTTABLE AS (
	SELECT 'TEST1' GROUPNAME , 'A,B,C,D,E' VALUENAME FROM DUAL
	UNION ALL
	SELECT 'TEST2' GROUPNAME , 'A,B,C,D' VALUENAME FROM DUAL
)
SELECT
			GROUPNAME,
			SUBSTR( A.VALUENAME, INSTR( A.VALUENAME, ',', 1, LEVELS.LVL ) + 1, INSTR( A.VALUENAME, ',', 1, LEVELS.LVL + 1 ) -( INSTR( A.VALUENAME, ',', 1, LEVELS.LVL ) + 1 )) AS VALUENAME
		FROM
			(
				SELECT
					GROUPNAME,
					',' || VALUENAME || ',' AS VALUENAME,
					LENGTH(VALUENAME) - NVL( LENGTH( REPLACE( VALUENAME, ',' )), 0 ) + 1 AS CNT
					--取待拆分字段每行按照分隔符','分割后的记录数，用于CONNECT BY
				FROM
					TESTTABLE
			) A,
			(
				SELECT
					ROWNUM AS LVL
					--产生一个待拆分字段分割后最大记录数的序列
				FROM
					(
						SELECT
							MAX( LENGTH( VALUENAME || ',' ) - NVL( LENGTH( REPLACE( VALUENAME, ',' )), 0 )) MAX_LEN
						FROM
							TESTTABLE
					)
				CONNECT BY
					LEVEL <= MAX_LEN
			) LEVELS
		WHERE
			LEVELS.LVL <= A.CNT
			--笛卡尔连接
		ORDER BY
			GROUPNAME