Multiple methods for mysqli to process query result sets in PHP

Recently, I looked up information that I didn’t quite understand about several methods of PHP query mysql processing result sets, so I compiled them here (related recommendations: mysql tutorial)

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

fetch_all()	grab Takes all result rows and returns the result set as associative data, a numerically indexed array, or both.
fetch_array()	Fetch as an associative array, a numeric index array, or both Get a row of results.
fetch_object()	Returns the current row of the result set as an object.
fetch_row()	Returns a row of results in the form of an enumeration array
fetch_assoc()	Fetch a row of results in an associative array.
fetch_field_direct()	Returns the metadata of a single field in the result set as an object.
fetch_field()	Returns the column information in the result set as an object.
fetch_fields()	Returns the column information representing the result set in an object array .

fetch_all (Get all rows from the result set as an associative array)

  $sql="select * from user";
  $result=$link->query($sql);
  $row=$result->fetch_all(MYSQLI_BOTH);//参数MYSQL_ASSOC、MYSQLI_NUM、MYSQLI_BOTH规定产生数组类型
  $n=0;
  while($n<mysqli_num_rows></mysqli_num_rows>";
   $n++;
  }

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

 $sql="select * from user";
        $result=$link->query($sql);
        while($row=$result->fetch_array()){
            echo "ID:".$row["id"]."用户名：".$row[1]."密码：".$row["password"]."<br>";
        }
//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

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

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

fetch_row (Return a row of results in the form of an enumeration array)

  $sql="select * from user";
        $result=$link->query($sql);
        while($row=$result->fetch_row()){
            echo "ID:".$row[0]."用户名：".$row[1]."密码：".$row[2]."<br>";
        }
//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

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

 $sql="select * from user";
        $result=$link->query($sql);
        while($row=$result->fetch_assoc()){
            echo "ID:".$row["id"]."用户名：".$row["name"]."密码：".$row["password"]."<br>";
        }
//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

fetch_field_direct (Returns the metadata of a single field in the result set as an object and is a single column Information)

$sql="select * from user";
        $result=$link->query($sql);
        $n=0;
        while(1){
            if(!$row=$result->fetch_field_direct($n++)) break;
            echo "列名:".$row->name."所在表：".$row->table."数据类型：".$row->type."<br>";
        }
//fetch_field_direct（$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

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

       $sql="select * from user";
        $result=$link->query($sql);
        while($row=$result->fetch_field()){
            echo "列名:".$row->name."所在表：".$row->table."数据类型：".$row->type."<br>";
        }
//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

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

    $sql="select * from user";
        $result=$link->query($sql);
        $row=$result->fetch_fields();
        foreach($row as $val){
            echo "列名:".$val->name."所在表：".$val->table."数据类型：".$val->type."<br>";
        }
//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

Another: mysqli_result class has other Method

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

refer to Information: php manual (http://php.net/manual/zh/class.mysqli-result.php)

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