Several methods for mysqli in PHP to process query result sets, mysqli query results_PHP tutorial

Several methods of mysqli processing query result sets in php, mysqli query results

　Recently, I don’t quite understand the several methods of querying mysql processing result sets in php I checked the information and compiled it here

Php uses the mysqli_result class to process result sets in the following ways

fetch_all()	抓取所有的结果行并且以关联数据，数值索引数组，或者两者皆有的方式返回结果集。
fetch_array()	以一个关联数组，数值索引数组，或者两者皆有的方式抓取一行结果。
fetch_object()	以对象返回结果集的当前行。
fetch_row()	以枚举数组方式返回一行结果
fetch_assoc()	以一个关联数组方式抓取一行结果。
fetch_field_direct()	以对象返回结果集中单字段的元数据。
fetch_field()	以对象返回结果集中的列信息。
fetch_fields()	以对象数组返回代表结果集中的列信息。

fetch_all (fetch all rows from result set as associative array)

  <span>$sql</span>="select * from user"<span>;
  </span><span>$result</span>=<span>$link</span>->query(<span>$sql</span><span>);
  </span><span>$row</span>=<span>$result</span>->fetch_all(MYSQLI_BOTH);<span>//</span><span>参数MYSQL_ASSOC、MYSQLI_NUM、MYSQLI_BOTH规定产生数组类型</span>
  <span>$n</span>=0<span>;
  </span><span>while</span>(<span>$n</span><<span>mysqli_num_rows</span>(<span>$result</span><span>)){
   </span><span>echo</span> "ID:".<span>$row</span>[<span>$n</span>]["id"]."用户名：".<span>$row</span>[<span>$n</span>]["name"]."密码：".<span>$row</span>[<span>$n</span>]["password"]."<br />"<span>;
   </span><span>$n</span>++<span>;
  }</span>

fetch_array (Fetch a row of results as an associative array, a numeric index array, or both)

        <span>$sql</span>="select * from user"<span>;
        </span><span>$result</span>=<span>$link</span>->query(<span>$sql</span><span>);
        </span><span>while</span>(<span>$row</span>=<span>$result</span>-><span>fetch_array()){
            </span><span>echo</span> "ID:".<span>$row</span>["id"]."用户名：".<span>$row</span>[1]."密码：".<span>$row</span>["password"]."<br />"<span>;
        }
</span><span>//</span><span>fetch_array方法不再有结果时返回返回NULL
//其返回结果可以是关联数组也可以是数值数组索引,故$row["id"]、$row[1]都可以</span>

fetch_object (Returns the current row of the result set as an object)

        $sql=<span>"</span><span>select * from user</span><span>"</span><span>;
        $result</span>=$link-><span>query($sql);
        </span><span>while</span>($row=$result-><span>fetch_object()){
            echo </span><span>"</span><span>ID:</span><span>"</span>.$row->id.<span>"</span><span>用户名：</span><span>"</span>.$row->name.<span>"</span><span>密码：</span><span>"</span>.$row->password.<span>"</span><span><br /></span><span>"</span><span>;
        }
</span><span>//</span><span>如果无更多的行则返回NULL
</span><span>//</span><span>返回的结果是对象，要以对象的方式调用</span>

fetch_row (Returns one row of results in an enumeration array)

        <span>$sql</span>="select * from user"<span>;
        </span><span>$result</span>=<span>$link</span>->query(<span>$sql</span><span>);
        </span><span>while</span>(<span>$row</span>=<span>$result</span>-><span>fetch_row()){
            </span><span>echo</span> "ID:".<span>$row</span>[0]."用户名：".<span>$row</span>[1]."密码：".<span>$row</span>[2]."<br />"<span>;
        }
</span><span>//</span><span>无更多行时返回NULL
//以数值下标调用数组，a[0]正确、a["id"]则不</span>

fetch_assoc (Fetch a row of results in an associative array)

        <span>$sql</span>="select * from user"<span>;
        </span><span>$result</span>=<span>$link</span>->query(<span>$sql</span><span>);
        </span><span>while</span>(<span>$row</span>=<span>$result</span>-><span>fetch_assoc()){
            </span><span>echo</span> "ID:".<span>$row</span>["id"]."用户名：".<span>$row</span>["name"]."密码：".<span>$row</span>["password"]."<br />"<span>;
        }
</span><span>//</span><span>无更多行时返回NULL
//以关联索引访问数组，a["id"]正确、a[0]则不</span>

fetch_field_direct (Returns the metadata of a single field in the result set as a single column of information )

        <span>$sql</span>="select * from user"<span>;
        </span><span>$result</span>=<span>$link</span>->query(<span>$sql</span><span>);
        </span><span>$n</span>=0<span>;
        </span><span>while</span>(1<span>){
            </span><span>if</span>(!<span>$row</span>=<span>$result</span>->fetch_field_direct(<span>$n</span>++)) <span>break</span><span>;
            </span><span>echo</span> "列名:".<span>$row</span>->name."所在表：".<span>$row</span>->table."数据类型：".<span>$row</span>->type."<br />"<span>;
        }
</span><span>//</span><span>fetch_field_direct（$n）只返回单个列,所以得不断调用该方法，没有该列时返回false</span>

fetch_field (returns the column information in the result set as an object)

        <span>$sql</span>="select * from user"<span>;
        </span><span>$result</span>=<span>$link</span>->query(<span>$sql</span><span>);
        </span><span>while</span>(<span>$row</span>=<span>$result</span>-><span>fetch_field()){
            </span><span>echo</span> "列名:".<span>$row</span>->name."所在表：".<span>$row</span>->table."数据类型：".<span>$row</span>->type."<br />"<span>;
        }
</span><span>//</span><span>该方法检索所有的列
//以对象方式返回列信息
//返回对象属性如：name - 列名，table - 该列所在的表名，type - 该列的类型，等</span>

fetch_fields (returns column information representing the result set as an object array)

        <span>$sql</span>="select * from user"<span>;
        </span><span>$result</span>=<span>$link</span>->query(<span>$sql</span><span>);
        </span><span>$row</span>=<span>$result</span>-><span>fetch_fields();
        </span><span>foreach</span>(<span>$row</span> <span>as</span> <span>$val</span><span>){
            </span><span>echo</span> "列名:".<span>$val</span>->name."所在表：".<span>$val</span>->table."数据类型：".<span>$val</span>->type."<br />"<span>;
        }
</span><span>//</span><span>该方法功能与目的fetch_field一样
//不一样的是该方法返回一个对象数组(如：echo $row[0]->name;输出第一列的名字），而不是一次检索一列</span>

Another: The mysqli_result class has other methods

field_tell()	返回字段指针的位置
data_seek()	调整结果指针到结果集中的一个任意行
num_fields()	返回结果集中的字段数（列数）
field_seek()	调整字段指针到特定的字段开始位置
free()	释放与某个结果集相关的内存
fetch_lengths()	返回结果集中当前行的列长度
num_rows()	返回结果集中的行数

field_tell()

Returns the position of the field pointer

data_seek()

Adjust the result pointer to an arbitrary row in the result set

num_fields()

Returns the number of fields (number of columns) in the result set

field_seek()

Adjust the field pointer to the specific field start position

free()

Release the memory associated with a result set

fetch_lengths()

Returns the column length of the current row in the result set

num_rows()

Returns the number of rows in the result set

Reference material: php manual (http://php.net/manual/zh/class.mysqli-result.php)

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