Oracle sumvalue和加法怎么可以为空

如何对

NULL

值求和

例如：

select sum(nvl(a,0) + nvl(b,0)) s,  c from 
(
select 1 a, null b, 'A' c from dual union 
select null, null b , 'c' c from dual
)
group by c

---

预期结果：当

a

为

NULL

时，

b

为

NULL

则

sum（nvl（a，0）+nvl（b，0））

为

NULL

。如何执行此操作？

使用

CASE

语句检测

a

和

B

何时为

NULL

：

Oracle 11g R2架构设置：

CREATE TABLE sample_data ( a, b, c ) AS
SELECT 1, CAST( NULL AS NUMBER ), 'A' FROM DUAL UNION ALL
SELECT NULL, NULL, 'C' FROM DUAL

SELECT SUM(
         CASE
         WHEN a IS NULL AND b IS NULL
         THEN NULL
         ELSE nvl(a,0) + nvl(b,0)
         END
       ) AS s,
       c
FROM   sample_data
GROUP BY c

|      S | C |
|--------|---|
|      1 | A |
| (null) | C |

查询1：

CREATE TABLE sample_data ( a, b, c ) AS
SELECT 1, CAST( NULL AS NUMBER ), 'A' FROM DUAL UNION ALL
SELECT NULL, NULL, 'C' FROM DUAL

SELECT SUM(
         CASE
         WHEN a IS NULL AND b IS NULL
         THEN NULL
         ELSE nvl(a,0) + nvl(b,0)
         END
       ) AS s,
       c
FROM   sample_data
GROUP BY c

|      S | C |
|--------|---|
|      1 | A |
| (null) | C |

：

CREATE TABLE sample_data ( a, b, c ) AS
SELECT 1, CAST( NULL AS NUMBER ), 'A' FROM DUAL UNION ALL
SELECT NULL, NULL, 'C' FROM DUAL

SELECT SUM(
         CASE
         WHEN a IS NULL AND b IS NULL
         THEN NULL
         ELSE nvl(a,0) + nvl(b,0)
         END
       ) AS s,
       c
FROM   sample_data
GROUP BY c

|      S | C |
|--------|---|
|      1 | A |
| (null) | C |

---

使用

CASE

语句检测

a

和

B

何时为

NULL

：

Oracle 11g R2架构设置：

CREATE TABLE sample_data ( a, b, c ) AS
SELECT 1, CAST( NULL AS NUMBER ), 'A' FROM DUAL UNION ALL
SELECT NULL, NULL, 'C' FROM DUAL

SELECT SUM(
         CASE
         WHEN a IS NULL AND b IS NULL
         THEN NULL
         ELSE nvl(a,0) + nvl(b,0)
         END
       ) AS s,
       c
FROM   sample_data
GROUP BY c

|      S | C |
|--------|---|
|      1 | A |
| (null) | C |

查询1：

CREATE TABLE sample_data ( a, b, c ) AS
SELECT 1, CAST( NULL AS NUMBER ), 'A' FROM DUAL UNION ALL
SELECT NULL, NULL, 'C' FROM DUAL

SELECT SUM(
         CASE
         WHEN a IS NULL AND b IS NULL
         THEN NULL
         ELSE nvl(a,0) + nvl(b,0)
         END
       ) AS s,
       c
FROM   sample_data
GROUP BY c

|      S | C |
|--------|---|
|      1 | A |
| (null) | C |

：

CREATE TABLE sample_data ( a, b, c ) AS
SELECT 1, CAST( NULL AS NUMBER ), 'A' FROM DUAL UNION ALL
SELECT NULL, NULL, 'C' FROM DUAL

SELECT SUM(
         CASE
         WHEN a IS NULL AND b IS NULL
         THEN NULL
         ELSE nvl(a,0) + nvl(b,0)
         END
       ) AS s,
       c
FROM   sample_data
GROUP BY c

|      S | C |
|--------|---|
|      1 | A |
| (null) | C |

您可以尝试：

select Case when (sum(nvl(a,0) + nvl(b,0))) = 0 then null 
else sum(nvl(a,0) + nvl(b,0)) end s,  c 
from 
(
select 1 a, null b, 'A' c from dual union 
select null, null b , 'c' c from dual
)
group by c

您可以尝试：

select Case when (sum(nvl(a,0) + nvl(b,0))) = 0 then null 
else sum(nvl(a,0) + nvl(b,0)) end s,  c 
from 
(
select 1 a, null b, 'A' c from dual union 
select null, null b , 'c' c from dual
)
group by c

---

oracle还是sql server？请选择正确的标签。您的问题不清楚。请编辑它。sql-server是否相同？我要alloracle还是sql server？请选择正确的标签。您的问题不清楚。请编辑它。sql-server是否相同？我要求所有，但如果我有很多列，例如sum（a+b+c+d+…），那么很难判断何时？@ILoveYou否-只需包括所有术语：

如果a为NULL，b为NULL，c为NULL，c为NULL，d为NULL，则为NULL，否则为NVL（a，0）+NVL（b，0）+NVL c，0）+NVL d（d，0）END（a+b+c+d+…）很难区分什么时候？@ILoveYou不-只需包括所有术语：
如果a为空，b为空，c为空，d为空，则为空，否则NVL（a，0）+NVL（b，0）+NVL（c，0）+NVL（d，0）结束
如果某些值为0（而不是全部
空
）然后，即使存在已知值，输出也将为
NULL
。如果某些值为0（而不是所有
NULL
），则即使存在已知值，输出也将为
NULL
。