I have a php comma seperated string
$string = (x,y,z)
I have a column in mysql that has items (y,z)
how do i compare the two and echo which items in $string are not in the column?
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4 Answers
I think that should do the trick. Good Luck.
$myString="v1,v2,v3";
$stringA=explode(",",$myString);
$result=mysql_query("SELECT * FROM data");
while($row = mysql_fetch_array($result)){
$data=$row['dataColumn'];
if (!in_array($data,$stringA)) echo $data . "<br>";
}//end while
If you have data that needs to be exploded in the column we can go deeper.
$myString="v1,v2,v3";
$stringA=explode(",",$myString);
$result=mysql_query("SELECT * FROM data");
while($row = mysql_fetch_array($result)){
$data=$row['dataColumn'];
$da=explode(",",$data);
foreach($da as $value) if (!in_array($value,$stringA)) echo $data . "<br>";
}//end while
3 Comments
Michael Mior
There's rarely a good reason for doing
SELECT * FROM data. If the goal is to check the value of one column, it would be good to select only that column. It's also good to consider only fetching data for the rows that need to be tested instead of the whole table.
Adam Fowler
Yeah I know this. I'm just used to doing it this way.
Michael Mior
Just pointing this out for the benefit of the OP since it's bad practice.
I think you want to compute differente in two comma separated strings.
Just convert your strings in to array using explode and use array_diff
array_diff - Computes the difference of arrays
Example :
<?php
$array1=explode(",",$string);
$array2=explode(",",$yourstring_of_db_column);
$array1 = array("x", "y", "z");
$array2 = array( "y","z");
$result = array_diff($array1, $array2);
print_r($result);
?>
Be aware Values are compared using ===, so 1 and "1" are considered different.
Comments
the logic behind this is first explode the string with the explode(", ", $string) function.
So that it will become an array.
And on the other hand check the value with the function in_array(),
For example:
$a = array(array('p', 'h'), array('p', 'r'), 'o');
if (in_array(array('p', 'h'), $a)) {
echo "'ph' was found\n";
}
//output : 'ph' was found
3 Comments
Michael Mior
This doesn't explain how to compare with data stored in MySQL.
jogesh_pi
@MichaelMior i just clear the logic, because the asker didn't provide any code,
Michael Mior
The OP didn't mention anything about nested arrays. You might consider simplifying your example.
you could solve this with one query, retrieving just the rows that do not match, eg.:
$string= "(str1, str2, str3)"; //formatted as the OP indicated
$input = explode(",",trim($string,"() "));
$filter = "(".$input[1].",".$input[2].")";
$sql = "select interestingColumn from greatTable where interestingColumn not like '".$filter."'";
$rez = mysql_query($sql);
while($row = mysql_fetch_array($rez)){
echo $row["interestingColumn"]."<br>\n";
}
this has the added benefit of retrieving fewer results from the database, which is desirable especially if you have a large dataset
edit : fixed a typo on the second line (thanks Michael)
2 Comments
Michael Mior
@Bogan The stuff in
$filter needs to be quoted and potentially escaped. You also have several syntax errors on the second line.
Bogdan
yes, obviously you need to filter your data and make it secure, i was trying a barebones implementation to show the general idea (didn't run the code, so syntax errors are probable)
