最近对php查询mysql处理结果集的几个方法不太明白的地方查阅了资料，在此整理记下
Php使用mysqli_result类处理结果集有以下几种方法
| 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 (从结果集中取得所有行作为关联数组)
<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 (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)
<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 (以对象返回结果集的当前行)
$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 (以枚举数组方式返回一行结果)
<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>$row</span>[2]."<br />"<span>;
}
</span><span>//</span><span>无更多行时返回NULL
//以数值下标调用数组，a[0]正确、a["id"]则不</span>
fetch_assoc (以一个关联数组方式抓取一行结果)
<span>$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 (以对象返回结果集中单字段的元数据既单列的信息)
<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 (以对象返回结果集中的列信息)
<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>$row</span>->type."<br />"<span>;
}
</span><span>//</span><span>该方法检索所有的列
//以对象方式返回列信息
//返回对象属性如：name - 列名，table - 该列所在的表名，type - 该列的类型，等</span>
fetch_fields (以对象数组返回代表结果集中的列信息)
<span>$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>另：mysqli_result类还有其他方法
|
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 |
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| num_rows() | 返回结果集中的行数 |
