PHP Mysql_fetch_array fails if fieldname is 0

using mysql_fetch_array() for a simple query-

SELECT id, name, roll FROM student

I get->

Array (
    [0] => 1
    [id] => 1
    [1] => sam
    [name] => sam
    [2] => 5
    [roll] => 5
)

But, if I replace roll with 0->

SELECT id, name, 0 FROM student

It sends->

Array (
    [0] => 0
    [id] => 1
    [1] => sam
    [name] => sam
    [2] => 0
)

The 'id' is giving '0'. Whereas the query works well in mysql.

is it a bug of mysql_fetch开发者_运维百科_array?

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It is not a bug. The array value with key as 0 is being overwritten.

Since you've not specified any alias for the column with constant value 0 its column name will be 0. And this column name when it becomes the key in the array will overwrite the array the already existing value with key 0.

[0] => 1      // for id
[id] => 1 

[1] => sam    // for name
[name] => sam 

[0] => 0     // for 0 .. THIS WILL OVERWRITE.

Easiest way to fix this is to provide a column alias as:

SELECT id, name, 0 AS FOO FROM student

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mysql_fetch_array takes two arguments. You signal with the second one how you want to get your results.

MYSQL_ASSOC will give you an associative array with field names (or even 0 if you decide to use it as a field name). You will get:

Array ( [id] => 1 [name] => sam [roll] => 5 )

MYSQL_NUM will give the resulting rows indexed with numbers, in the order you asked for them. You will get:

Array ( [0] => 1 [1] => sam [2] => 5 )

MYSQL_BOTH is the default, it will populate your array both ways and can complicate things like this.

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You should use mysql_fetch_assoc instead.

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Another solution is to change your query to:

SELECT id, name, 0 AS zero FROM student