COUNT 多种类型的同一列

Question

在我当前的查询中：

SELECT COUNT(WC.ID) AS "Regions" 
FROM WHOLE_FEATURES_PDB_CHAINS AS WC 
;

我COUNT(WC.ID) AS "Regions" 。 但是，我们有多个区域，WC.Type 可以是1,2,3,4。我需要将每种类型的出现计数为COUNT(WC.ID) AS "Region_1"、COUNT(WC.ID) AS "Region_2" ...，具体取决于WC.Type。 有没有办法在一个查询中解决这个问题？我正在看 MySQL IF，但不知道如何将它集成到 count 函数中。

我需要它在一行中（这里显示的查询减少了，这是一个更大的查询）

SELECT COUNT(WC.ID) AS "Region_1" , COUNT(WC.ID) AS "Region_2" ...

如果有人感兴趣，这里是完整的查询：

SELECT PCS.PDB_id, PCS.Chain, PPA.ENSEMBL_start, PPA.ENSEMBL_end, PPA.eValue, PIN.TITLE AS "pdbTitle", COUNT(WC.ID) AS "Regions" 
FROM PDB_Chains AS PCS 
LEFT JOIN WHOLE_FEATURES_PDB_CHAINS AS WC ON WC.PDB_CHAIN_ID = PCS.idPDB_chains, PDB_protein_alignment PPA, PDB_INFOS PIN 
WHERE PCS.idPDB_chains = PPA.idPDB_Chains 
AND PCS.PDB_id = PIN.PDB_ID 
AND PPA.idProteins = (SELECT idProteins from Proteins WHERE ENSEMBL_protein_id = "'+submittedID+'") 
GROUP BY PCS.PDB_id, PCS.Chain ORDER BY PCS.PDB_id;

---

这是基于您的回答的有效解决方案

SELECT PIN.TITLE AS "pdbTitle", COUNT(CASE WHEN WC.STRUCTURAL_FEATURES_ID = 1 then 1 end) AS "PPInterface" , COUNT(CASE WHEN WC.STRUCTURAL_FEATURES_ID = 4 then 1 end) AS "flexibleRegions" 
FROM PDB_Chains AS PCS LEFT JOIN WHOLE_FEATURES_PDB_CHAINS AS WC ON WC.PDB_CHAIN_ID = PCS.idPDB_chains, PDB_protein_alignment PPA, PDB_INFOS PIN 
WHERE PCS.idPDB_chains = PPA.idPDB_Chains 
AND PCS.PDB_id = PIN.PDB_ID 
AND PPA.idProteins = (SELECT idProteins from Proteins WHERE ENSEMBL_protein_id = "ENSP00000256078.4") 
GROUP BY PCS.PDB_id, PCS.Chain ORDER BY PCS.PDB_id;

Answer 1

您可以在聚合函数中使用 case when 语句。

试试这个。

count(WC.type = 1 then 1 end) as region_1，类似地重复另一列。

Answer 2

Select
...
...
sum(if WC.ID = 1 then 1 else 0) as Region1,
sum(if WC.ID = 2 then 1 else 0) as Region2,
sum(if WC.ID = 3 then 1 else 0) as Region3,
sum(if WC.ID = 4 then 1 else 0) as Region4

可以做你想做的。

Answer 3

您可以使用GROUP BY 和COUNT 来获得所需的结果，例如：

SELECT WC.Type, COUNT(WC.ID) AS "Regions" 
FROM WHOLE_FEATURES_PDB_CHAINS AS WC 
GROUP BY WC.Type;

更新

如果您希望将计数作为每个区域的透视列，那么您可以编写内部 SELECT 查询，例如：

SELECT
 (SELECT COUNT(ID) FROM WHOLE_FEATURES_PDB_CHAINS WHERE type = 1) AS "Region_1",
 (SELECT COUNT(ID) FROM WHOLE_FEATURES_PDB_CHAINS WHERE type = 2) AS "Region_2",
other_column
FROM WHOLE_FEATURES_PDB_CHAINS AS WC
WHERE <some condition>;