w取最大db_id。
1 if($row=null){ 2 var_dump(123); 3 } 4 var_dump($row); 5 6 if($rowb=array('ww','w123')){ 7 var_dump(234); 8 } 9 var_dump($rowb); 10 11 $rowc=null; 12 if($rowc=null){ 13 var_dump(345); 14 } 15 var_dump($rowc);
| NULL | |
| int(234) | |
| array(2) { | |
| [0]=> | |
| string(2) "ww" | |
| [1]=> | |
| string(4) "w123" | |
| } | |
| NULL |
Returns an associative array that corresponds to the fetched row or NULL if there are no more rows.
1 id wint wchar 2 1 1001 1001www 3 2 1002 1002www 4 3 1003 1003www 5 4 1004 1004www 6 5 1005 1005www 7 6 1006 1006www 8 7 1007 1007www 9 8 1008 1008www 10 9 1009 1009www 11 10 1010 1010www 12 11 1011 1011www 13 12 1012 1012www 14 13 1013 1013www 15 14 1014 1014www 16 15 1015 1015www 17 16 1016 1016www 18 UPDATE w1 SET wint=id+1000; 19 UPDATE w1 SET wchar=CONCAT(wint,'www'); 20 DELETE FROM w1 WHERE id>16;
1 $sql = 'SELECT * FROM w1 '; 2 if ($result = mysqli_query($link, $sql)) { 3 while ($row = mysqli_fetch_assoc($result)) { 4 $w_id = $row['id']; 5 } 6 // mysqli_free_result($result); 7 } 8 var_dump($w_id); 9 var_dump($row); 10 var_dump($result);
string(2) "16" NULL object(mysqli_result)#3 (5) { ["current_field"]=> int(0) ["field_count"]=> int(3) ["lengths"]=> NULL ["num_rows"]=> int(16) ["type"]=> int(0) }
1 $sql = 'SELECT * FROM w1 '; 2 if ($result = mysqli_query($link, $sql)) { 3 while ($row = mysqli_fetch_assoc($result)) { 4 $w_id = $row['id']; 5 } 6 mysqli_free_result($result); 7 } 8 var_dump($w_id); 9 var_dump($row); 10 var_dump($result);
string(2) "16" NULL
Warning: var_dump() [function.var-dump]: Couldn't fetch mysqli_result
Warning: var_dump() [function.var-dump]: Couldn't fetch mysqli_result
Warning: var_dump() [function.var-dump]: Property access is not allowed yet
Warning: var_dump() [function.var-dump]: Couldn't fetch mysqli_result
Warning: var_dump() [function.var-dump]: Property access is not allowed yet
object(mysqli_result)#3 (5) { ["current_field"]=> NULL ["field_count"]=> NULL ["lengths"]=> NULL ["num_rows"]=> NULL ["type"]=> NULL }