Detailed explanation of mysql's database operation function encapsulation

Most of today's PHP operation databases are implemented using mysqli, and it is also very easy to use when implementing mysqli operation database and e-commerce backend management. Since the frequency of use is so high, there is no choice but to To encapsulate the function library, there is no class method for encapsulation here, but a simple structure-oriented method, which is summarized in a unified way:

(1) Connect to the database:

function connect(){

    @$link = mysqli_connect(DB_HOST,DB_USER,DB_PWD);//连接数据库
    mysqli_set_charset($link,DB_CHARSET);//设置数据库字体格式
    mysqli_select_db($link,DB_DBNAME) or die('数据库打开失败');//选择数据库

    if(mysqli_connect_errno())
    {
        die('数据库连接失败 : '.mysqli_connect_errno());
    }

    return $link;
}

(2) Insert data

function insert($link,$table,$array){
    $keys = join(',',array_keys($array));
    $values = "'".join(',',array_values($array))."'";
    $sql = 'insert into {$table}({$keys}) values({$values})';

    mysqli_query($link,$sql);

    return mysqli_insert_id($link);
}

(3) Modify data

function update($link,$table,$array,$where = null) {
     $setstr = ''; 
     foreach ($array as $key => $value) 
     {
        $setstr .= (' '.$key.'='.$value.' '); 
        if(!$setstr){ 
             $sep = '';
        }else{ 
             $sep = ','; 
        } 
        $setstr .= $sep.$key.'='."'"$value"'";
     } 

     $sql = "update {$table} set {$setstr}".($where ? 'where '.$where : ''); 
     mysqli_query($link,$sql); 

     return mysqli_affected_rows($link); 
}

(4) Delete data

function delete($link,$table,$where = null)
{
    $sql = "delete from {$table}".($where?'where '.$where : '');
    mysqli_query($link,$sql);

    return mysqli_affected_rows($link); 
}

(5) Find a record

function fetchOne($link,$sql,$result_type=MYSQLI_ASSOC)
{
    $result = mysqli_query($link,$sql);

    $row = mysqli_fetch_array($result,$result_type);

    return $row;
}

(6) Find multiple records

function fetchAll($link,$sql,$result_type=MYSQLI_ASSOC)
{
    $result = mysqli_query($link,$sql);

    while(@$row = mysqli_fetch_array($result,$result_type))
    {
        $row[] = $row;
    }

    return $row;
}

(7) Return the number of rows in the result set

function getResultNum($link,$sql)
{
    $result = mysqli_query($link,$sql);

    return mysqli_num_rows($result);
}

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