Can we use multiple AND conditions for the same column in WHERE clause?

Question

I tried using AND for the same column in WHERE clause, but it is not giving me any output. But there are two Customer names in the data set which satisfies the given condition. Where have I gone wrong?

SELECT CONCAT(c.CustFirstName," ",c.CustLastName) AS CustomerName
FROM Musical_Preferences mp
JOIN Customers c ON c.CustomerID = mp.CustomerID 
WHERE mp.StyleID = 15 AND mp.StyleID = 24; 

This above query worked fine when I put OR for same column in WHERE clause, but why not for AND?

My data:

CustomerID  CustFirstName   CustLastName    CustStreetAddress       CustCity    CustState   CustZipCode CustPhoneNumber CustomerID  StyleID PreferenceSeq
10001       Doris           Hartwig         4726 - 11th Ave. N.E.   Seattle     WA          98105       555-2671        10001       10      2
10001       Doris           Hartwig         4726 - 11th Ave. N.E.   Seattle     WA          98105       555-2671        10001       22      1

Answer 1

The condition StyleID = 15 AND StyleID = 24 can never return anything because it can never be true. So what you're getting is expected. If you want to get the customers that have both StyleID 15 and 24 (in different records), then you need to group the records by customer:

SELECT CONCAT(c.CustFirstName," ",c.CustLastName) AS CustomerName
FROM Musical_Preferences mp
JOIN Customers c ON c.CustomerID = mp.CustomerID 
WHERE mp.StyleID IN(15, 24)
GROUP BY c.CustomerID, c.CustFirstName, c.CustLastName
HAVING COUNT(mp.CustomerID) = 2;

I added c.CustFirstName and c.CustLastName to the GROUP BY. Alternatively, you can only group by the ID and then use MIN() or MAX() on the first and last name. Both ways are more or less then same.

This query will only work if your data can never have a customer with the same StyleID more than once (example: customer 1001 has 3 records with StyleID 15, 24, and 24).

Answer 2

WHERE conditions operate on rows created by the FROM clause, not across rows if you try WHERE somefield = 1 AND somefield = 2 you will never get results, a field cannot have two values at the same time.

I think what you are looking for is

SELECT ...
FROM ...
WHERE somefield IN (15, 24)
GROUP BY ...
HAVING COUNT(DISINCT somefield ) = 2
;

Answer 3

If your query with a single condition does not return any row, your query won't return any row.

Please try this:

SELECT CONCAT(c.CustFirstName," ",c.CustLastName) AS CustomerName
FROM Musical_Preferences mp
JOIN Customers c ON c.CustomerID = mp.CustomerID 
WHERE mp.StyleID = 24;

Does it return anything?