Oracle case when then else end的兩種用法

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查詢表結構

　　

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;

　　第二種：紅色部分可以把 T.DATA_TYPE 欄位移動到CASE，WHEN 之間，這樣when之後就直接寫DATA_TYPE對應的值即可

 

Oracle case when then else end的兩種用法