select s.MountingsName as '品名',s.TypeSpecification as '規格',s.MaterialCode as '物料代碼',s.Number as '庫存數',
CASE
WHEN s.IsSafeStock=0 THEN '不滿足'
WHEN s.IsSafeStock=1 THEN '滿足'
END as '是否滿足安全庫存'
from CommonlyUsedAccessories as c left join Stock_Information as s on c.CuaId=s.MaterialCode
1.第一種寫法:
SELECT
s.s_id,
s.s_name,
s.s_sex,
CASE
WHEN s.s_sex = '1' THEN '男'
WHEN s.s_sex = '2' THEN '女'
ELSE '其他'
END as sex,
s.s_age,
s.class_id
FROM
t_b_student s
WHERE
1 = 1
2.第二種寫法
SELECT
s.s_id,
s.s_name,
s.s_sex,
CASE s.s_sex
WHEN '1' THEN '男'
WHEN '2' THEN '女'
ELSE '其他'
END as sex,
s.s_age,
s.class_id
FROM
t_b_student s
WHERE
1 = 1
兩個運行結果一樣:
有一個需要注意的問題,Case函數只返回第一個符合條件的值,剩下的Case部分將會被自動忽略
二:分組
表數據:
t_b_population
sql語句:
SELECT country,
SUM(CASE WHEN p.sex = '1' THEN p.population ELSE 0 END) AS '男',
SUM(CASE WHEN p.sex = '2' THEN p.population ELSE 0 END) AS '女'
FROM
t_b_population p
GROUP BY country;
運行結果:
表數據:
t_b_country
sql語句:
SELECT
SUM(c.population) AS '人口',
CASE c.country
WHEN '中國' THEN '亞洲'
WHEN '印度' THEN '亞洲'
WHEN '日本' THEN '亞洲'
WHEN '美國' THEN '北美洲'
WHEN '加拿大' THEN '北美洲'
WHEN '墨西哥' THEN '北美洲'
ELSE '其他' END AS '洲'
FROM
t_b_country c
GROUP BY CASE c.country
WHEN '中國' THEN '亞洲'
WHEN '印度' THEN '亞洲'
WHEN '日本' THEN '亞洲'
WHEN '美國' THEN '北美洲'
WHEN '加拿大' THEN '北美洲'
WHEN '墨西哥' THEN '北美洲'
ELSE '其他' END;
運行結果:
分類: 數據庫