PHP connects to mysql database_PHP tutorial

php connects to mysql database

Today I learned to use php to connect to mysql database and write a blog to summarize it.
To connect to the mysql database using php, we must first connect to the database. We use the following function to connect

$sql_link = mysql_connect("主机名","登入用户名","登入用户名密码");

If the connection is successful, a mysql handle will be returned. It can be simply understood that this $sql_link is a bridge between php and mysql, through which we can enter mysql.
After entering mysql, we need to select a database and operate mysql. We use the following function to select a database

mysql_select_db("数据库名","这个参数可以不要");

After that we execute some mysql statements and use the following function

$result = mysql_query( "sql语句","这个参数可以不要");

When executing some mysql statements, there are two situations:
1. No results are returned, such as deleting data, modifying encoding, etc.
2. If there is a return result, such as query data, we use a variable to receive it. For example, the following statement returns a table, which can be regarded as a two-dimensional array.

$result = mysql_query( "select * from person_list",$sql_link );//返回一个资源，目前是一张表

You can know a lot of information about this table through $result. We need to use the corresponding function to get the information we need.
1. This table has several fields.

mysql_num_fields( $result );

2. This table has several records.

mysql_num_rows( $result );

3. The field name of this table.

mysql_field_name( $result, $index );

4. Obtain the array one by one by indexing the array, and perform pointer offset once.

mysql_fetch_row( $result );

5. Obtain the array one by one in an associative array manner, and perform pointer offset once.

mysql_fetch_assoc( $result );

6. Specify the position of the pointer yourself.

mysql_data_seek( $result, 3 );

7. Sometimes we operate on the database and judge whether it was successful by the number of rows affected.

mysql_affected_rows();//可以有参数

A completed code is given below to demonstrate reading data information (person_list table under test database) and displaying it on the page (the problem of garbled characters on the page will not be dealt with yet).

<!--?php
    header(&#39;Content-type: text/html; charset=UTF-8&#39;);

    //要连接的数据库的信息
    define("DB_HOST","localhost");//主机名
    define("DB_USER","root");//登入户名
    define("DB_USER_PWD","rootmysql");//登入用户密码

    //连接到数据库
    $sql_link = mysql_connect(DB_HOST,DB_USER,DB_USER_PWD);
    if( $sql_link )//判断是否连接成功
        echo "连接数据库成功<br /-->";
    else
        echo mysql_error( $sql_link )."
";

    $db_name = "test";//要连接哪个数据库
    mysql_select_db($db_name,$sql_link);

    $sql_sentence = "select * from person_list";//要执行的SQL语句
    //$sql_sentence = "desc person_list";//要执行的SQL语句
    $result = mysql_query( $sql_sentence,$sql_link );//返回一个资源，目前是一张表

    echo &#39;&#39;;
        echo &#39;&#39;;
            for( $index = 0; $index < mysql_num_fields( $result ); $index++ )
                echo &#39;&#39;;
        echo &#39;&#39;;
        while( $row = mysql_fetch_row( $result ) )
        {
            echo &#39;&#39;;
                foreach( $row as $value )
                    echo &#39;&#39;;//echo &#39;&#39;;
            echo &#39;&#39;;
        }
    echo &#39;

'.mysql_field_name( $result, $index ).'
'.$value.'	'.$value.'

'; ?>

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