To count ALL users which selected a BLACK BALL, try this query:
SELECT COUNT(userID)
FROM table1
WHERE itemID = 1 AND itemType = 1
I am not sure what you mean by "How can I count the primary key of this table"
Frage
I have a table the primary key of which is a composite formed on 3 columns:
userID FK of users table
itemID FK of items table
itemType FK of itemtypes table
Primary Key is combination of (userID, itemID, itemType )
Assume: itemID 1 is a BALL, and itemType 1 is BLACK COLOR.
so in below example,
User 1 is selecting a BALL which is BLACK
User 2 is selecting a BALL which is WHITE
User 3 is selecting a BALL which is BLACK
+------+------+--------+
|userID|itemID|itemType|
+------+------+--------+
| 1 | 1 | 1 |
+------+------+--------+
| 2 | 1 | 2 |
+------+------+--------+
| 3 | 1 | 1 |
Now I want to count ALL users which selected a BLACK BALL, How can I count the primary key of this table which is composite
Thanks in advanced.
Lösung 2
To count ALL users which selected a BLACK BALL, try this query:
SELECT COUNT(userID)
FROM table1
WHERE itemID = 1 AND itemType = 1
I am not sure what you mean by "How can I count the primary key of this table"
Andere Tipps
I solved for this by concating the composite key, and counting that:
SELECT COUNT( CONCAT(userID, '-', itemID, '-', itemType) ) FROM myTable