case when

case when 的简单使用：

如：

SELECT BAE001,
       (CASE AAE180
         WHEN 30 THEN
          '学生'
         WHEN 104 THEN
          '低保,残疾'
         WHEN 160 THEN
          '成年人'
       END) AAE180,
       COUNT(DISTINCT(AAC001)) aac001 
  FROM SKC84
 WHERE AAE140 IN ('340', '350')
   AND AAE341 = '0'
   AND AAE180 IN (30, 104, 160)
 GROUP BY BAE001, AAE180
 ORDER BY BAE001;

查询结果：