While working with PHP ,handling connection's with Database (MySQL)
$result = mysql_query('select * from products');
$row = mysql_fetch_array($result);
And yesterday founded out that array $row had Duplicate data within.
First you have Data's selected from database arranged in Indexes like : $row[0] = ID; than you also could find $row['ID'] = ID.
So is this only a feature of the Framework ,which copies data Virtually or are these Data's stored twice in array .
To get only one value set, you need to pass a second parameter to mysql_fetch_array.
either "MYSQL_ASSOC" to get an associative array, or "MYSQL_NUM" to get a normal array.
Example:
$row = mysql_fetch_array($result, 'MYSQL_ASSOC')
This will return:
$row['id']
Documentation
Straight from the manual:
mysql_fetch_array — Fetch a result row as an associative array, a
numeric array, or both
The prototype of the function says that
array mysql_fetch_array ( resource $result [, int $result_type = MYSQL_BOTH ] )
meaning that it returns both arrays by default - that is - duplicating the info
mysql_fetch_array fetches a result row as an associative array, a numeric array, or both. Please see: mysql_fetch_array.
Each row in $result has an index, a name and a value. You can look up a row's value by either index or name.
See the documentation for mysql_fetch_array()
Default setting is to fetch an array with both numeric and associative array. See PHP manual to change that.
Related
I have a script that is outputting to a CSV file. However, even though there is currently one row in the database, the output I'm getting is echoing out each column from each row in the table twice.
For example:
1,1,John,John,Smith,Smith,2014,2014
Should be
1,John,Smith,2014
This worked fine before I went with PDO and prepared statements, so I'm thinking maybe I'm not understanding how fetch() works correctly.
Below is my code. Any idea what I could be doing wrong?
// get rows
$query_get_rows = "SELECT * FROM Contacts ORDER BY date_added DESC";
$result_get_rows = $conn->prepare($query_get_rows);
$result_get_rows->execute();
$num_get_rows = $result_get_rows->rowCount();
while ($rows_get_rows = $result_get_rows->fetch())
{
$csv .= '"'.join('","', str_replace('"', '""', $rows_get_rows))."\"\n";
}
echo $csv;
exit;
You should say to PDO, that you want only an associative array or a numbered array:
while ($rows_get_rows = $result_get_rows->fetch(PDO::FETCH_ASSOC))
to get an associative array or
while ($rows_get_rows = $result_get_rows->fetch(PDO::FETCH_NUM))
to get an array indexed by the column number
from PDOStatement::fetch
fetch_style
Controls how the next row will be returned to the caller.
This value must be one of the PDO::FETCH_* constants, defaulting to
value of PDO::ATTR_DEFAULT_FETCH_MODE (which defaults to
PDO::FETCH_BOTH).
PDO::FETCH_ASSOC: returns an array indexed by column name as returned
in your result set
PDO::FETCH_BOTH (default): returns an array indexed by both column
name and 0-indexed column number as returned in your result set
I have a script that is outputting to a CSV file. However, even though there is currently one row in the database, the output I'm getting is echoing out each column from each row in the table twice.
For example:
1,1,John,John,Smith,Smith,2014,2014
Should be
1,John,Smith,2014
This worked fine before I went with PDO and prepared statements, so I'm thinking maybe I'm not understanding how fetch() works correctly.
Below is my code. Any idea what I could be doing wrong?
// get rows
$query_get_rows = "SELECT * FROM Contacts ORDER BY date_added DESC";
$result_get_rows = $conn->prepare($query_get_rows);
$result_get_rows->execute();
$num_get_rows = $result_get_rows->rowCount();
while ($rows_get_rows = $result_get_rows->fetch())
{
$csv .= '"'.join('","', str_replace('"', '""', $rows_get_rows))."\"\n";
}
echo $csv;
exit;
You should say to PDO, that you want only an associative array or a numbered array:
while ($rows_get_rows = $result_get_rows->fetch(PDO::FETCH_ASSOC))
to get an associative array or
while ($rows_get_rows = $result_get_rows->fetch(PDO::FETCH_NUM))
to get an array indexed by the column number
from PDOStatement::fetch
fetch_style
Controls how the next row will be returned to the caller.
This value must be one of the PDO::FETCH_* constants, defaulting to
value of PDO::ATTR_DEFAULT_FETCH_MODE (which defaults to
PDO::FETCH_BOTH).
PDO::FETCH_ASSOC: returns an array indexed by column name as returned
in your result set
PDO::FETCH_BOTH (default): returns an array indexed by both column
name and 0-indexed column number as returned in your result set
I am querying the database for all values in one column, then putting it into an associative array. The db query is working, but PHP prints an array with only one item.
<?php
$acc_names = mysqli_query($con,"SELECT acc_name FROM accounts"); #successfully returns all values in column in mysql
$acc_names = (mysqli_fetch_assoc($acc_names));
print_r($acc_names); #only one item in array
print_r($acc_names['acc_name']); #that one item
?>
You should use mysqli_fetch_all($acc_names, MYSQLI_ASSOC) instead of mysqli_fetch_assoc.
$q = "SELECT * FROM user";
$res = mysqli_query($conn, $q) or die(mysql_error());
$userList = "";
while($user = mysqli_fetch_array($res))
{
$userList .= $user['userList'].";;";
}
echo $userList;
I don't understand the while part:
Why assign the mysqli_fetch_array to $user using while?
How can the $user have index of userList?
Why concatenate with ;;?
To answer your questions:
i) mysqli_fetch_array() has two possible return values. It either returns an array of the current row that the database result set pointer points to, then advances the pointer to the next row, or it returns false if you have reached the end of the result set. The while() evaluates the value that is set to $row either continuing the loop if it is an array or stopping the loop if $row equals false
ii) The $user array has both numerical indexes for each field (i.e. 0,1,2,... [#fields - 1]) and associative indexes of the column names for the table (i.e. 'field1', 'field2', etc.). In this case one of the fields in the database is userList, so accessing $user['userList'] returns that column value for the row being worked with. BNote that the query itself would have beeter been written as SELECT userList FROM user since that is the only field you are interested in. There is no reason whatsoever to select and transfer all field data if you have no need for it. It is also rarely useful to use just mysqli_fetch_array(), as you rarely need both numerical and associative indexes on the record.It is usually best to specifically request ther associative or numerical array result depending on which you need.
iii) This code is simply building a string rather than an array of results which might be more common. For whatever reason the code writer decided values in the string should be separated by ;;.
Now we can access the values from mysql result set based on the index and/or with the name.
For eg: SELECT name,id FROM tbl_user
name = resultset[0] OR name = resultset['name']
I need to retrieve the values from mysql result set with only index or with name.
i am using PHP.
You can get result row as an associative array, a numeric array, or both.
mysql_fetch_array can be used. Use make of the second optional parameter to get the result in desired array type.
array mysql_fetch_array ( resource $result [, int $result_type = MYSQL_BOTH ] )
result type can be MYSQL_ASSOC, MYSQL_NUM or MYSQL_BOTH (default)
you can also use the mysql_fetch_assoc, if you need result only an associative array.
use
mysql_fetch_array($resultset);
or to get associative array use
mysql_fetch_assoc($resultset);
Check this link for details mysql fetch array