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SQL programming(cha 10), PHP programming(cha 11), types, 无需事先声明变量类型,…

- - - - Single-line comments
        
        started by //
        
        started with #,
      - Multiple-line comments
        
        /*and end with* /
    - - predefined PHP variable
        
        an array that
        holds all the values entered through form parameters.
        
        dynamic arrays
        
        no fixed number of elements
        
        numerically indexed arrays whose indexes (positions) are numbered (0, 1, 2, … ),
        
        associative arrays whose indexes can be any string values.
        
        When the Web page first opened
        
        empty
      - auto-global
    - - All text between an
        opening <<<_HTML_ and a closing_HTML_;is printed into the HTML file as
        
        closing _HTML_; must be alone on a separate line
      - HTML 本质就是长文本字符？
    - - start with a $ sign
      - can include characters, numbers, and the underscore character _
      - 举例
        
        $_SERVER
        
        an array that includes information about the local server
        
        $_SERVER['PHP_SELF'] in the array is the path
        name of the PHP file currently being executed on the server
        
        the action attribute of the form tag instructs the PHP interpreter to reprocess the same file, once the form parameters are entered by the user.
    - - depending on the particular conditional paths taken in the program.
- - - - case sensitive
      - Variables are not typed
    - - Single-quoted strings
      - Double-quoted strings
        
        interpolating variables within strings
      - Here documents
        
        between a <<<DOCNAME and end it with a single line containing the document name DOCNAME
        
        DOCNAME can be any string
      - string concatenate operator specified by the period (.) symbol,
        
        function
        
        strtolower
        
        ucwords
      - general rule
        
        use single-quoted strings for literal strings
        
        真没比要。。。、
        
        use double-quoted strings and here documents when the values from variables need to be interpolated into the string
        
        use the here documents style
        for strings For large blocks of multiline text,
    - - printf('The cost is $%.2f and the tax is $%.2f', $cost, $tax) ;
    - - Boolean expression
      - comparison operators
  - - - database query results
    - - hold the list of choices in the pull-down menu
    - - associates a numeric index (or position or sequence number) with
        each element in the array
    - - pairs of (key => value) element
        
        values can be arrays
        
        leading to higher dimensional arrays
  - - - 。。。
    - - calls can't change artuments values in the memory
    - - GLOBALS['abc'] will
        access the value in a global variable $abc defined outside the function.
      - ariables appearing inside a function are local even if there is a global
        variable with the same name.
  - - - information about
        the server where the PHP interpreter is running
        
        不太一样
        
        ？needed when creating
        the HTML file
        
        $_SERVER['REMOTE_ADDRESS']
        
        IP (Internet Protocol) address
        of the client user computer that is accessing the server
        
        怎么是remote？不是local？
        
        $_SERVER['REMOTE_HOST']
        
        Web site name (URL) of the client
        user computer
        
        so i have a ip and a url?
        
        the server will need to
        translate the name into an IP address to access the client.
        
        $_SERVER['SERVER_NAME']
        
        provides the Web site name or the Uniform
        Resource Locator (URL) of the server computer where the PHP interpreter is running.
        
        why do i need it?
        
        $_SERVER['PATH_INFO']
        
        part of the URL address that comes
        after a backslash (/) at the end of the URL
        
        server？client？
        
        $_SERVER['QUERY_STRING']
        
        provides the string that holds parameters
        in a URL after a question mark (?) at the end of the URL
        
        hold
        search parameters, for example.
        
        $_SERVER['DOCUMENT_ROOT']
        
        root directory that holds the
        files on the Web server that are accessible to client users.
      - other information
        
        ？？？
    - - provides the programmer with input values submitted by the user
        
        through HTML
        forms specified in the HTML <INPUT> tag and other similar tags.
      - The keys to this array are the names of the various input
        parameters provided via the form,
- - - - various techniques
        
        PHP open source
        server side scripting language
        
        PHP Hypertext Processor
        
        interpreters for PHP
        
        free of charge
        
        written in the C language
        
        available on most computer platforms
        
        execute PHP commands in a text file????
        
        create the desired HTML file
        
        access databases
        
        1 more item...
        
        executed on the Web server computer
        
        1 more item...
        
        JavaScript, Ruby, Python, and PERL
    - - behind the scene，对于数据库，完成对客户输入数据的保存POST，或者完成客户请求的数据检索GET。
- - - - Java environment has components that run on the server and other components that can run on the client machine.
        
        SQLJ
        
        ？？
        
        Java Servlets
        
        Java objects that can reside on the Web server
        machine and manage interactions with the client.
        
        JDBC
        
        ？？
        
        Java Server Pages (JSP).
        
        allows scripting at the server to produce dynamic Web
        pages to be sent at the client in a manner somewhat similar to PHP
        
        JavaScript.
        
        a scripting language that is different from the Java
        programming language and was developed separately
        
        widely used in Web
        applications
        
        can run on the client computer or on the server.
        
        Java Script Object Notation (JSON).
        
        a text-based representation of
        data objects
        
        data can be formatted in JSON and exchanged between
        clients and servers over the Web in text format.
        
        就是一种数据存储形式，全文本
        
        an alternative
        to XML
        
        ？？？
        
        represents objects using attribute-value
        pairs
        
        adopted as the data model
        
        NOSQL systems, such as MongoDB
        
        ？？
  - - - part of PHP Extension and
        Application Repository (PEAR)
        
        a collection of several libraries of functions
        for enhancing PHP.
      - provides functions for database
        access
      - Many database systems can be accessed
        
        Oracle,
        MySQL, SQLite, and Microsoft SQLServer,
  - - - Connecting to a Database
        
        require 'DB.php';
        
        加载模块
        
        $d = DB::connect('oci8://acct1:pass12@www.host.com/db1');
        
        database connection variable $d, which is used whenever
        an operation to this particular database is applied.
        
        ？？？
        
        string argument specifies the database information
        
        <DBMS software>://<user account>:<password><database server>
        
        <DBMS software> 举例 Oracle (specified
        via the string oci8)
        
        MySQL. Specified as mysql for earlier versions and mysqli for later versions
        starting with version 4.1.2.
        
        SQLite. Specified as sqlite.
        
        Microsoft SQL Server. Specified as mssql.
        
        ...
        
        server name and directory <database server> where the
        database is stored.
        
        DB::isError($d)
        
        determine whether any database access operation
        was successful or not
        
        die("cannot connect − " . $d->getMessage());
        
        Terminate the program (using the die function) if it
        was not successful. An error message is also returned
        
        $q = $d->query()
        
        takes an SQL command as its string argument
        and sends it to the database server for execution
        
        the result of the query is
        assigned to a query variable,
        
        ???return什么呢
        
        DB::isError($q)
        
        checks whether the query was executed successfully or not.
        
        $d–>setErrorHandling(PEAR_ERROR_DIE)
        
        an alternative to having to check for errors after
        every database command
        
        terminate the program and print the default error messages if any subsequent
        errors occur when accessing the database through connection $d
    - - $eid = $d->nextID('EMPLOYEE');
        
        function $d–>nextID to create a sequence of unique values for a particular
        table.
      - $q = $d->query("INSERT INTO EMPLOYEE VALUES ($eid, $_POST['emp_name'], $_POST['emp_job'], $_POST['emp_dno'])" );
        
        may allow malicious strings to be
        entered that can alter the INSERT command
        
        safer way to do inserts and other
        queries is through the use of placeholders (specified by the ? symbol)
        
        two arguments.
        
        The first argument is the SQL
        statement, with one or more ? symbols (placeholders
        
        The second argument is an
        array, whose element values be used to replace the placeholders in the order
        they are specified
    - - while ($r = $q->fetchRow()) {
        print "employee $r[0] works for department $r[1] \n" ;}
        
        serves to retrieve the next record in the query result and to control the
        loop
      - $q = $d->query('SELECT Name FROM EMPLOYEE WHERE Job = ? AND Dno = ?',
        array($_POST['emp_job'], $_POST['emp_dno']) );
        
        dynamic query
        
        conditions for selection of rows are based on values
        input by the user
      - $allresult = $d->getAll('SELECT Name, Job, Dno FROM EMPLOYEE');
        
        foreach ($allresult as $r) {
        print "employee $r[0] has job $r[1] and works for department $r[2] \n" ;}