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Editorial Team
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Asked: 2026-06-18T02:55:07+00:00

Table pc – code model speed ram hd cd price 1 1232 500 64

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Table pc –

 code   model   speed   ram hd  cd  price
 1  1232    500 64  5.0 12x 600.0000
 10 1260    500 32  10.0    12x 350.0000
 11 1233    900 128 40.0    40x 980.0000
 12 1233    800 128 20.0    50x 970.0000
 2  1121    750 128 14.0    40x 850.0000
 3  1233    500 64  5.0 12x 600.0000
 4  1121    600 128 14.0    40x 850.0000
 5  1121    600 128 8.0 40x 850.0000
 6  1233    750 128 20.0    50x 950.0000
 7  1232    500 32  10.0    12x 400.0000
 8  1232    450 64  8.0 24x 350.0000
 9  1232    450 32  10.0    24x 350.0000

Desired output –

model   speed   hd
1232    450 10.0
1232    450 8.0
1232    500 10.0
1260    500 10.0

Query 1 –

SELECT model, speed, hd
FROM pc
WHERE cd = '12x' AND price < 600
OR
cd = '24x' AND price < 600

Query 2 – 

SELECT model, speed, hd
FROM pc
WHERE cd = '12x' OR cd = '24x' 
AND price < 600

Query 1 is definitely working correctly, however when i tried to reduce the query to use price at once only, it is not showing the correct result..let me know what I am missing in the logic.

Find the model number, speed and hard drive capacity of the PCs having
12x CD and prices less than $600 or having 24x CD and prices less than
$600.

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1 Answer

  1. Editorial Team

    Since AND comes before OR, your query is being interpreted as:

    WHERE (cd = '12x') OR ((cd = '24x') AND (price < 600))

    Or, in words: All PCs having 12x CD, or PCs < $600 having 24x CD

    You need to use parentheses to specify order of operations:

    WHERE (cd = '12x' OR cd = '24x') AND price < 600

    Or, you can use IN:

    WHERE cd IN ('12x', '24x') AND price < 600

    See Also: http://dev.mysql.com/doc/refman/5.5/en/operator-precedence.html

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