MySQL中insert语句的使用与优化教程

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MySQL中insert语句的使用与优化教程_MySQL

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May 27, 2016 pm 01:45 PM

insertmysql

MySQL 表中使用 INSERT INTO SQL语句来插入数据。
你可以通过 mysql> 命令提示窗口中向数据表中插入数据，或者通过PHP脚本来插入数据。
语法
以下为向MySQL数据表插入数据通用的 INSERT INTO SQL语法：

INSERT INTO table_name ( field1, field2,...fieldN )
            VALUES
            ( value1, value2,...valueN );

如果数据是字符型，必须使用单引号或者双引号，如："value"。
通过命令提示窗口插入数据
以下我们将使用 SQL INSERT INTO 语句向 MySQL 数据表 runoob_tbl 插入数据
实例
以下实例中我们将想 runoob_tbl 表插入三条数据:

root@host# mysql -u root -p password;
Enter password:*******
mysql> use RUNOOB;
Database changed
mysql> INSERT INTO runoob_tbl 
   ->(runoob_title, runoob_author, submission_date)
   ->VALUES
   ->("Learn PHP", "John Poul", NOW());
Query OK, 1 row affected (0.01 sec)
mysql> INSERT INTO runoob_tbl
   ->(runoob_title, runoob_author, submission_date)
   ->VALUES
   ->("Learn MySQL", "Abdul S", NOW());
Query OK, 1 row affected (0.01 sec)
mysql> INSERT INTO runoob_tbl
   ->(runoob_title, runoob_author, submission_date)
   ->VALUES
   ->("JAVA Tutorial", "Sanjay", '2007-05-06');
Query OK, 1 row affected (0.01 sec)
mysql>

注意：使用箭头标记(->)不是SQL语句的一部分，它仅仅表示一个新行，如果一条SQL语句太长，我们可以通过回车键来创建一个新行来编写SQL语句，SQL语句的命令结束符为分号（;）。
在以上实例中，我们并没有提供 runoob_id 的数据，因为该字段我们在创建表的时候已经设置它为 AUTO_INCREMENT(自动增加) 属性。所以，该字段会自动递增而不需要我们去设置。实例中 NOW() 是一个 MySQL 函数，该函数返回日期和时间。
使用PHP脚本插入数据
你可以使用PHP 的 mysql_query() 函数来执行 SQL INSERT INTO命令来插入数据。
该函数有两个参数，在执行成功时返回 TRUE，否则返回 FALSE。
语法

bool mysql_query( sql, connection );

参数：
sql：必需，规定要发送的 SQL 查询，注意、查询字符串不应以分号结束。
connection：可选，规定 SQL 连接标识符，如果未规定，则使用上一个打开的连接。
实例
以下实例中程序接收用户输入的三个字段数据，并插入数据表中：

<html>
<head>
<title>向 MySQL 数据库添加数据</title>
</head>
<body>
<&#63;php
if(isset($_POST['add']))
{
$dbhost = 'localhost:3036';
$dbuser = 'root';
$dbpass = 'rootpassword';
$conn = mysql_connect($dbhost, $dbuser, $dbpass);
if(! $conn )
{
 die('Could not connect: ' . mysql_error());
}

if(! get_magic_quotes_gpc() )
{
  $runoob_title = addslashes ($_POST['runoob_title']);
  $runoob_author = addslashes ($_POST['runoob_author']);
}
else
{
  $runoob_title = $_POST['runoob_title'];
  $runoob_author = $_POST['runoob_author'];
}
$submission_date = $_POST['submission_date'];

$sql = "INSERT INTO runoob_tbl ".
    "(runoob_title,runoob_author, submission_date) ".
    "VALUES ".
    "('$runoob_title','$runoob_author','$submission_date')";
mysql_select_db('RUNOOB');
$retval = mysql_query( $sql, $conn );
if(! $retval )
{
 die('Could not enter data: ' . mysql_error());
}
echo "Entered data successfully\n";
mysql_close($conn);
}
else
{
&#63;>
<form method="post" action="<&#63;php $_PHP_SELF &#63;>">
<table width="600" border="0" cellspacing="1" cellpadding="2">
<tr>
<td width="250">Tutorial Title</td>
<td>
<input name="runoob_title" type="text" id="runoob_title">
</td>
</tr>
<tr>
<td width="250">Tutorial Author</td>
<td>
<input name="runoob_author" type="text" id="runoob_author">
</td>
</tr>
<tr>
<td width="250">Submission Date [ yyyy-mm-dd ]</td>
<td>
<input name="submission_date" type="text" id="submission_date">
</td>
</tr>
<tr>
<td width="250"> </td>
<td> </td>
</tr>
<tr>
<td width="250"> </td>
<td>
<input name="add" type="submit" id="add" value="Add Tutorial">
</td>
</tr>
</table>
</form>
<&#63;php
}
&#63;>
</body>
</html>

在我们接收用户提交的数据时，为了数据的安全性我们需要使用 get_magic_quotes_gpc() 函数来判断特殊字符的转义是否已经开启。如果这个选项为off（未开启），返回0，那么我们就必须调用addslashes 这个函数来为字符串增加转义。
义。
你也可以添加其他检查数据的方法，比如邮箱格式验证，电话号码验证，是否为整数验证等。

优化 insert 性能
mysql 的 insert 语句语法

insert into `table`(`field1`,`field2`) values('value1','value2');

提高insert 性能的方法
1.一条sql语句插入多条数据

INSERT INTO `insert_table` (`uid`, `content`, `type`) VALUES ('userid_0', 'content_0', 0); 
INSERT INTO `insert_table` (`uid`, `content`, `type`) VALUES ('userid_1', 'content_1', 1);

可以写成

代码如下:

INSERT INTO `insert_table` (`uid`, `content`, `type`) VALUES ('userid_0', 'content_0', 0), ('userid_1', 'content_1', 1);

2.使用事务

START TRANSACTION; 
INSERT INTO `insert_table` (`uid`, `content`, `type`) VALUES ('userid_0', 'content_0', 0); 
INSERT INTO `insert_table` (`uid`, `content`, `type`) VALUES ('userid_1', 'content_1', 1); 
... 
COMMIT;

注意
1.sql语句长度有限制，合并sql语句时要注意。长度限制可以通过max_allowed_packet配置项修改，默认为1M。
2.事务太大会影响执行效率，mysql有innodb_log_buffer_size配置项，超过这个值会使用磁盘数据，影响执行效率。

关于事务的配置项说明：
1.innodb_buffer_pool_size
如果用Innodb，那么这是一个重要变量。相对于MyISAM来说，Innodb对于buffer size更敏感。MySIAM可能对于大数据量使用默认的key_buffer_size也还好，但Innodb在大数据量时用默认值就感觉在爬了。 Innodb的缓冲池会缓存数据和索引，所以不需要给系统的缓存留空间，如果只用Innodb，可以把这个值设为内存的70%-80%。和 key_buffer相同，如果数据量比较小也不怎么增加，那么不要把这个值设太高也可以提高内存的使用率。

2.innodb_additional_pool_size
这个的效果不是很明显，至少是当操作系统能合理分配内存时。但你可能仍需要设成20M或更多一点以看Innodb会分配多少内存做其他用途。

3.innodb_log_file_size
对于写很多尤其是大数据量时非常重要。要注意，大的文件提供更高的性能，但数据库恢复时会用更多的时间。我一般用64M-512M，具体取决于服务器的空间。

4.innodb_log_buffer_size
默认值对于多数中等写操作和事务短的运用都是可以的。如果经常做更新或者使用了很多blob数据，应该增大这个值。但太大了也是浪费内存，因为1秒钟总会 flush（这个词的中文怎么说呢？）一次，所以不需要设到超过1秒的需求。8M-16M一般应该够了。小的运用可以设更小一点。

5.innodb_flush_log_at_trx_commit
抱怨Innodb比MyISAM慢 100倍？那么你大概是忘了调整这个值。默认值1的意思是每一次事务提交或事务外的指令都需要把日志写入（flush）硬盘，这是很费时的。特别是使用电池供电缓存（Battery backed up cache）时。设成2对于很多运用，特别是从MyISAM表转过来的是可以的，它的意思是不写入硬盘而是写入系统缓存。日志仍然会每秒flush到硬盘，所以你一般不会丢失超过1-2秒的更新。设成0会更快一点，但安全方面比较差，即使MySQL挂了也可能会丢失事务的数据。而值2只会在整个操作系统挂了时才可能丢数据。

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