Oracle case when then else end的两种用法

SELECT
T.COLUMN_ID,
T.COLUMN_NAME,
(CASE
WHEN (T.DATA_TYPE = 'VARCHAR2' OR T.DATA_TYPE = 'RAW') THEN
T.DATA_TYPE || '(' || T.DATA_LENGTH || ')'
WHEN (T.DATA_TYPE = 'NUMBER' AND T.DATA_PRECISION IS NOT NULL) THEN
T.DATA_TYPE || '(' || T.DATA_PRECISION || ',' || T.DATA_SCALE || ')'
ELSE
T.DATA_TYPE
END) AS DATA_TYPE,
B.COMMENTS
FROM USER_TAB_COLUMNS T
INNER JOIN ALL_COL_COMMENTS B
ON B.COLUMN_NAME = T.COLUMN_NAME
AND T.TABLE_NAME = B.TABLE_NAME
AND T.TABLE_NAME = 'T_WEIXIN_REMIND_FUND_CHANGE'
ORDER BY T.COLUMN_ID;