mysql - 如何根据条件对列进行计数？

Question

我正在尝试计算 state = 0 和 state = 1 以及如果其他状态没有值则显示 0。

我的表:

|policies|
  |id|  |client|  |policy_business_unit_id|  |cia_ensure_id|   |state|       
   1      MATT                  1                   1             0
   2      STEVE                 2                   1             0
   3      BILL                  3                   2             1
   4      LARRY                 4                   2             1

|policy_business_units|
   |id|   |name|  |comercial_area_id|
     1     LIFE         2 
     2     ROB          1
     3     SECURE       2
     4     ACCIDENT     1

|comercial_areas|
   |id|   |name|
    1      BANK
    2      HOSPITAL

|cia_ensures|
   |id|   |name|
    1      SPRINT
    2      APPLE

信息如下:

http://sqlfiddle.com/#!2/54d2f/15

我正在尝试获取 states = 0,1,2 anc 计数，如果它不存在或显示 0

Select p.id, p.client, 
  pb.name as BUSINESS_UNITS,
  ce.name as CIA,ca.name as COMERCIAL_AREAS,
  count(p.state) as status_0,count(p.state) as status_1,count(p.state) as status_2
From policies p 
INNER JOIN policy_business_units pb ON pb.id = p.policy_business_unit_id
INNER JOIN comercial_areas ca ON ca.id = pb.comercial_area_id
INNER JOIN cia_ensures ce ON ce.id = p.cia_ensure_id

我得到这个结果:

ID  CLIENT  BUSINESS_UNITS      CIA      COMERCIAL_AREAS    STATE_0 STATE_1   STATUS_2
 1  MATT    LIFE             SPRINT       HOSPITAL                4    4           4

我正在尝试计算 state = 0,1,2 否则在没有值的状态下显示 0

我该怎么做才能得到这个结果？

ID      CLIENT      BUSINESS_UNITS      CIA        COMERCIAL_AREAS  STATE_0   STATE_1    STATE_2
 1      MATT         LIFE              SPRINT       HOSPITAL          1         0         0
 2      STEVE        ROB               SPRINT       BANK              1         0         0
 3      BILL         SECURE            APPLE        HOSPITAL          0         1         0
 4      LARRY        ACCIDENT          APPLE        BANK              0         1         0

拜托，我将不胜感激所有类型的帮助。 谢谢。

Answer 1

这应该可以解决问题。做一个 if 条件。如果 state = 0 然后计数 else 放入 0 查看工作 FIDDLE

SELECT
    p.id,
    p.client,
    pb.name AS BUSINESS_UNITS,
    ce.name AS CIA,ca.name AS COMERCIAL_AREAS,
    IF (p.state = 0, count(p.state), 0) AS state_0,
    IF (p.state = 1, count(p.state), 0) AS state_1,
    IF (p.state = 2, count(p.state), 0) AS state_2
FROM policies p
INNER JOIN policy_business_units pb ON pb.id = p.policy_business_unit_id
INNER JOIN comercial_areas ca ON ca.id = pb.comercial_area_id
INNER JOIN cia_ensures ce ON ce.id = p.cia_ensure_id
GROUP BY pb.id
ORDER BY p.id;

---

如果您想考虑空状态，这将是查询.. FIDDLE

SELECT
    p.id,
    p.client,
    pb.name AS BUSINESS_UNITS,
    ce.name AS CIA,ca.name AS COMERCIAL_AREAS,
    IF (p.state = 0, count(p.state), 0) AS state_0,
    IF (p.state = 1, count(p.state), 0) AS state_1,
    IF (p.state IS NULL, count(p.id), 0) AS state_null
FROM policies p
INNER JOIN policy_business_units pb ON pb.id = p.policy_business_unit_id
INNER JOIN comercial_areas ca ON ca.id = pb.comercial_area_id
INNER JOIN cia_ensures ce ON ce.id = p.cia_ensure_id
GROUP BY pb.id
ORDER BY p.id;