(PHP 5, PHP 7)
mysqli_result::fetch_array -- mysqli_fetch_array — Fetch a result row as an associative, a numeric array, or both
面向对象风格
过程化风格
Returns an array that corresponds to the fetched row or NULL if there
are no more rows for the resultset represented by the
result parameter.
mysqli_fetch_array() is an extended version of the mysqli_fetch_row() function. In addition to storing the data in the numeric indices of the result array, the mysqli_fetch_array() function can also store the data in associative indices, using the field names of the result set as keys.
Note: 此函数返回的字段名大小写敏感。
Note: 此函数将 NULL 字段设置为 PHP
NULL值。
If two or more columns of the result have the same field names, the last column will take precedence and overwrite the earlier data. In order to access multiple columns with the same name, the numerically indexed version of the row must be used.
result仅以过程化样式：由 mysqli_query()，mysqli_store_result() 或 mysqli_use_result()返回的结果集标识。
resulttype
This optional parameter is a constant indicating what type of array
should be produced from the current row data. The possible values for
this parameter are the constants MYSQLI_ASSOC,
MYSQLI_NUM, or MYSQLI_BOTH.
By using the MYSQLI_ASSOC constant this function
will behave identically to the mysqli_fetch_assoc(),
while MYSQLI_NUM will behave identically to the
mysqli_fetch_row() function. The final option
MYSQLI_BOTH will create a single array with the
attributes of both.
Returns an array of strings that corresponds to the fetched row or NULL if there
are no more rows in resultset.
Example #1 面向对象风格
<?php
$mysqli = new mysqli("localhost", "my_user", "my_password", "world");
/* check connection */
if ($mysqli->connect_errno) {
printf("Connect failed: %s\n", $mysqli->connect_error);
exit();
}
$query = "SELECT Name, CountryCode FROM City ORDER by ID LIMIT 3";
$result = $mysqli->query($query);
/* numeric array */
$row = $result->fetch_array(MYSQLI_NUM);
printf ("%s (%s)\n", $row[0], $row[1]);
/* associative array */
$row = $result->fetch_array(MYSQLI_ASSOC);
printf ("%s (%s)\n", $row["Name"], $row["CountryCode"]);
/* associative and numeric array */
$row = $result->fetch_array(MYSQLI_BOTH);
printf ("%s (%s)\n", $row[0], $row["CountryCode"]);
/* free result set */
$result->free();
/* close connection */
$mysqli->close();
?>
Example #2 过程化风格
<?php
$link = mysqli_connect("localhost", "my_user", "my_password", "world");
/* check connection */
if (mysqli_connect_errno()) {
printf("Connect failed: %s\n", mysqli_connect_error());
exit();
}
$query = "SELECT Name, CountryCode FROM City ORDER by ID LIMIT 3";
$result = mysqli_query($link, $query);
/* numeric array */
$row = mysqli_fetch_array($result, MYSQLI_NUM);
printf ("%s (%s)\n", $row[0], $row[1]);
/* associative array */
$row = mysqli_fetch_array($result, MYSQLI_ASSOC);
printf ("%s (%s)\n", $row["Name"], $row["CountryCode"]);
/* associative and numeric array */
$row = mysqli_fetch_array($result, MYSQLI_BOTH);
printf ("%s (%s)\n", $row[0], $row["CountryCode"]);
/* free result set */
mysqli_free_result($result);
/* close connection */
mysqli_close($link);
?>
以上例程会输出：
Kabul (AFG) Qandahar (AFG) Herat (AFG)
Please note that under PHP 5.x there appears to be a globally defined variable MYSQL_ASSOC, MYSQL_NUM, or MYSQL_BOTH which is the equivalent of MYSQLI_ASSOC, MYSQLI_NUM, or MYSQLI_BOTH!!! Yet under PHP 7.x this is NOT the case and will cause a failure in trying to retrieve the result set!
This can cause severe headaches when trying to find out why you are getting the error:
- mysqli_result::fetch_array() expects parameter 1 to be integer, string given in 'Filename' on line 'XX'
Note that the array returned contains only strings.
E.g. when a MySQL field is an INT you may expect the field to be returned as an integer, however all fields are simply returned as strings.
What this means: use double-equals not triple equals when comparing numbers.
<?php
print $array_from_mysqli_fetch_array['id'] == 1 ? "true" : "false"; // true
print $array_from_mysqli_fetch_array['id'] === 1 ? "true" : "false"; // false
?>
Here is a function to return an associative array with multiple columns as keys to the array.
This is a rough approximation of the perl DBI->fetchall_hashref function - something I find myself using quite a bit.
Given a simple mySQL table:
mysql> select * from city;
+----------------+----------------+------------------+------------+
| country | region | city | hemisphere |
+----------------+----------------+------------------+------------+
| South Africa | KwaZulu-Natal | Durban | South |
| South Africa | Gauteng | Johannesburg | South |
| South Africa | Gauteng | Tshwane | South |
| South Africa | KwaZulu-Natal | Pietermaritzburg | South |
| United Kingdom | Greater London | City of London | North |
| United Kingdom | Greater London | Wimbledon | North |
| United Kingdom | Lancashire | Liverpool | North |
| United Kingdom | Lancashire | Manchester | North |
+----------------+----------------+------------------+------------+
*Note* - this is a simple function that makes no attempt to keep multiple values per key, so you need to specify all the unique keys you require.
<?php
$link = mysqli_connect("localhost", "username", "password", "test");
$result = mysqli_query($link, "select * from city");
$results_arr = fetch_all_assoc($result,array('hemisphere','country','region','city'));
function fetch_all_assoc(& $result,$index_keys) {
// Args : $result = mysqli result variable (passed as reference to allow a free() at the end
// $indexkeys = array of columns to index on
// Returns : associative array indexed by the keys array
$assoc = array(); // The array we're going to be returning
while ($row = mysqli_fetch_array($result, MYSQLI_ASSOC)) {
$pointer = & $assoc; // Start the pointer off at the base of the array
for ($i=0; $i<count($index_keys); $i++) {
$key_name = $index_keys[$i];
if (!isset($row[$key_name])) {
print "Error: Key $key_name is not present in the results output.\n";
return(false);
}
$key_val= isset($row[$key_name]) ? $row[$key_name] : "";
if (!isset($pointer[$key_val])) {
$pointer[$key_val] = ""; // Start a new node
$pointer = & $pointer[$key_val]; // Move the pointer on to the new node
}
else {
$pointer = & $pointer[$key_val]; // Already exists, move the pointer on to the new node
}
} // for $i
// At this point, $pointer should be at the furthest point on the tree of keys
// Now we can go through all the columns and place their values on the tree
// For ease of use, include the index keys and their values at this point too
foreach ($row as $key => $val) {
$pointer[$key] = $val;
}
} // $row
/* free result set */
$result->close();
return($assoc);
}
?>
Putting multiple rows into an array:
<?php
$mysqli = new mysqli("localhost", "my_user", "my_password", "world");
/* check connection */
if (mysqli_connect_errno()) {
printf("Connect failed: %s\n", mysqli_connect_error());
exit();
}
$query = "SELECT Name, CountryCode FROM City ORDER by ID LIMIT 3";
$result = $mysqli->query($query);
while($row = $result->fetch_array())
{
$rows[] = $row;
}
foreach($rows as $row)
{
echo $row['CountryCode'];
}
/* free result set */
$result->close();
/* close connection */
$mysqli->close();
?>