The Introduction to PHP Tutorial uses mysqli to manipulate database methods (connection, query, transaction rollback, etc.) _php tips

The example in this article describes the approach to using mysqli to manipulate databases in the introductory PHP tutorial. Share to everyone for your reference, specific as follows:

demo1.php

<?php
  //Use Mysqli object to manipulate database
  //Create Mysqli object (resource handle)
  $_mysqli = new mysqli ();
  Connection database 1. Host name (IP) 2. Account 3 password 4. Database
  //mysqli_connect function = = $_mysqli-> connect ();
  $_mysqli-> Connect (' localhost ', ' root ', ' 123456 ', ' guest ');
  Disconnect MySQL mysqli_close () = = $_mysqli-> close ();
  $_mysqli-> Close ();
? >

demo2.php

<?php
  //without connect, use the construction method directly
  $_mysqli = new mysqli (' localhost ', ' root ', ' 123456 ', ' guest ');
  Select a single database
  //The database selected here will replace the above database
  //To avoid these problems, as far as possible without going to point to the
  //$_mysqli-> select_db (' School ');
  $_mysqli-> Close ();
? >

demo3.php

<?php
  header (' content-type:text/html; charset=utf-8; ');
  Connect MySQL
  //When you have an error in the parameter, causing the connection error, the
  //$_mysqli object is not created successfully, that is, the function without the resource handle
  //is the ability to invoke the methods and properties under Mysqli.
  @$_mysqli = new mysqli (' localhost ', ' root ', ' 123456 ', ' guest ');
  Why use a function to capture it?
  Why not use object-oriented approach to capture it?
  An error occurred in the IF (Mysqli_connect_errno ()) {
    echo ' database connection with the wrong message: '. Mysqli_connect_error ()
    ; Exit ();
  }
  $_mysqli->close ();
? >

demo4.php

<?php
  header (' content-type:text/html; charset=utf-8; ');
  Connect MySQL
  //When you have an error in the parameter, causing the connection error, the
  //$_mysqli object is not created successfully, that is, the function without the resource handle
  //is the ability to invoke the methods and properties under Mysqli.
  @$_mysqli = new mysqli (' localhost ', ' root ', ' 123456 ', ' guest ');
  Why use a function to capture it?
  Why not use object-oriented approach to capture it?
  An error occurred in the IF (Mysqli_connect_errno ()) {
    echo ' database connection with the wrong message: '. Mysqli_connect_error ()
    ; Exit ();
  }
  $_mysqli-> select_db (' FSDFD ');
  Error occurred in database operation
  if ($_mysqli-> errno) {
    echo ' database operation error: '. $_mysqli-> error;
  }
  $_mysqli->close ();
? >

demo5.php

<?php
  header (' content-type:text/html; charset=utf-8; ');
  $_mysqli = new mysqli (' localhost ', ' root ', ' 123456 ', ' testguest ');
  Error occurred during database connection
  if (Mysqli_connect_errno ()) {
    echo ' database connection error occurred, the error message is: '. Mysqli_connect_error ();
    Exit ();
  }
  Set the code
  $_mysqli-> set_charset (' UTF8 ');
  Create a SQL that gets the data for the table of the database
  $_sql = "SELECT * from Tg_user";
  Executes the SQL statement and assigns the result set to $_result
  $_result = $_mysqli-> query ($_sql);
  Var_dump ($_result); Object (Mysqli_result) #2 (0) {}
  //Through the result set, I want to get the first row of data
  //fetch_row (), an array to return, and a collection of the first Data
  Print_r ($_ Result-> Fetch_row ());
  Run once, the pointer moves down one
  print_r ($_result-> fetch_row ());
  Destroy result set
  $_result-> free ();
  $_mysqli->close ();
? >

demo6.php

<?php
  header (' content-type:text/html; charset=utf-8; ');
  $_mysqli = new mysqli (' localhost ', ' root ', ' 123456 ', ' testguest ');
  Error occurred during database connection
  if (Mysqli_connect_errno ()) {
    echo ' database connection has occurred. The wrong message is: '. Mysqli_connect_error ();
    Exit ();
  }
  Set the encoding
  $_mysqli->set_charset (' UTF8 ');
  Create a SQL that gets the data for the table of the database
  $_sql = "SELECT * from Tg_user";
  Create a result set
  $_result = $_mysqli->query ($_sql);
  Use an indexed array to
  //print_r ($_result->fetch_row ());
  $_row = $_result->fetch_row ();
  Echo $_row[3];
  Traversal, subscript hard to remember [3] while
  (!! $_row = $_result->fetch_row ()) {
    echo $_row[3]. ' <br/> ';
  }
  $_mysqli->close ();
? >

demo7.php

<?php
  header (' content-type:text/html; charset=utf-8; ');
  $_mysqli = new mysqli (' localhost ', ' root ', ' 123456 ', ' testguest ');
  Error occurred during database connection
  if (Mysqli_connect_errno ()) {
    echo ' database connection has occurred. The wrong message is: '. Mysqli_connect_error ();
    Exit ();
  }
  Set the encoding
  $_mysqli->set_charset (' UTF8 ');
  Create a SQL that gets the data for the table of the database
  $_sql = "SELECT * from Tg_user";
  Create a result set
  $_result = $_mysqli->query ($_sql);
  Use associative array to value
  //print_r ($_RESULT->FETCH_ASSOC ());
  $_ASSOC = $_result->fetch_assoc ();
  echo $_assoc[' Tg_username '];
  Traverse while
  (!! $_ASSOC = $_result->fetch_assoc ()) {
    echo $_assoc[' Tg_username ']. ' <br/> ';
  }
  $_mysqli->close ();
? >

demo8.php

<?php
  header (' content-type:text/html; charset=utf-8; ');
  $_mysqli = new mysqli (' localhost ', ' root ', ' 123456 ', ' testguest ');
  Error occurred during database connection
  if (Mysqli_connect_errno ()) {
    echo ' database connection has occurred. The wrong message is: '. Mysqli_connect_error ();
    Exit ();
  }
  Set the encoding
  $_mysqli->set_charset (' UTF8 ');
  Create a SQL that gets the data for the table of the database
  $_sql = "SELECT * from Tg_user";
  Create a result set
  $_result = $_mysqli->query ($_sql);
  Use index + associative array to fetch value
  //print_r ($_result->fetch_array ());
  $_array = $_result->fetch_array ();
  Echo $_array[3];
  echo $_array[' Tg_username '];
  Traverse ...
  .. $_mysqli->close ();
? >

demo9.php

<?php
  header (' content-type:text/html; charset=utf-8; ');
  $_mysqli = new mysqli (' localhost ', ' root ', ' 123456 ', ' testguest ');
  Error occurred during database connection
  if (Mysqli_connect_errno ()) {
    echo ' database connection has occurred. The wrong message is: '. Mysqli_connect_error ();
    Exit ();
  }
  Set the encoding
  $_mysqli->set_charset (' UTF8 ');
  Create a SQL that gets the data for the table of the database
  $_sql = "SELECT * from Tg_user";
  Create a result set
  $_result = $_mysqli->query ($_sql);
  Using Oop Method Object
  //print_r ($_result->fetch_object ());
  Echo $_result->fetch_object ()->tg_username;
  Use OOP to traverse while
  (!! $_object = $_result->fetch_object ()) {
    echo $_object->tg_username. ' <br/> ';
  }
  $_mysqli->close ();
? >

demo10.php

<?php
  header (' content-type:text/html; charset=utf-8; ');
  $_mysqli = new mysqli (' localhost ', ' root ', ' 123456 ', ' testguest ');
  Error occurred during database connection
  if (Mysqli_connect_errno ()) {
    echo ' database connection has occurred. The wrong message is: '. Mysqli_connect_error ();
    Exit ();
  }
  Set the encoding
  $_mysqli->set_charset (' UTF8 ');
  Create a SQL that gets the data for the table of the database
  $_sql = "SELECT * from Tg_user limit 0,10";
  Create a result set
  $_result = $_mysqli->query ($_sql);
  I want to see how many lines I've chosen.
  Echo $_result->num_rows;
  How many lines have I affected?
  echo $_mysqli->affected_rows;
  $_mysqli->close ();
? >

demo11.php

<?php
  header (' content-type:text/html; charset=utf-8; ');
  $_mysqli = new mysqli (' localhost ', ' root ', ' 123456 ', ' testguest ');
  Error occurred during database connection
  if (Mysqli_connect_errno ()) {
    echo ' database connection has occurred. The wrong message is: '. Mysqli_connect_error ();
    Exit ();
  }
  Set the encoding
  $_mysqli->set_charset (' UTF8 ');
  Create a SQL, get the database table of data
  $_sql = "UPDATE tg_user SET tg_username= ' one-stop building site ' WHERE tg_id=5 ';
  " Create a result set
  $_result = $_mysqli->query ($_sql);
  I want to see how many lines I've chosen.
  Echo $_result->num_rows;
  echo ' | ';
  How many lines have I affected?
  echo $_mysqli->affected_rows;
  $_mysqli->close ();
? >

demo12.php

<?php
  header (' content-type:text/html; charset=utf-8; ');
  $_mysqli = new mysqli (' localhost ', ' root ', ' 123456 ', ' testguest ');
  Error occurred during database connection
  if (Mysqli_connect_errno ()) {
    echo ' database connection has occurred. The wrong message is: '. Mysqli_connect_error ();
    Exit ();
  }
  Set the encoding
  $_mysqli->set_charset (' UTF8 ');
  Create a SQL that gets the data for the table of the database
  $_sql = "SELECT * from Tg_user";
  Create a result set
  $_result = $_mysqli->query ($_sql);
  Find out how many fields are in the table
  echo $_result->field_count;
  Gets the name of the field
//$_field = $_result->fetch_field ();
Echo $_field->name;
$_field = $_result->fetch_field ();
Echo $_field->name;
//while (!! $_field = $_result->fetch_field ()) {
//   echo $_field->name. ' <br/> ';
  //Get all the fields once
  $_fields = $_result->fetch_fields ();
  Echo $_fields[0]->name;
  foreach ($_fields as $_field) {
    echo $_field->name. ' <br/> ';
  }
  $_mysqli->close ();
? >

demo13.php

<?php
  header (' content-type:text/html; charset=utf-8; ');
  $_mysqli = new mysqli (' localhost ', ' root ', ' 123456 ', ' testguest ');
  Error occurred during database connection
  if (Mysqli_connect_errno ()) {
    echo ' database connection has occurred. The wrong message is: '. Mysqli_connect_error ();
    Exit ();
  }
  Set the encoding
  $_mysqli->set_charset (' UTF8 ');
  Create a SQL that gets the data for the table of the database
  $_sql = "SELECT * from Tg_user";
  Create a result set
  $_result = $_mysqli->query ($_sql);
  Moving data pointer
  $_result->data_seek (9);
  $_row = $_result->fetch_row ();
  Echo $_row[3];
  Move field Pointer
  $_result->field_seek (3);
  $_field = $_result->fetch_field ();
  Echo $_field->name;
  $_mysqli->close ();
? >

demo14.php

<?php
  header (' content-type:text/html; charset=utf-8; ');
  $_mysqli = new mysqli (' localhost ', ' root ', ' 123456 ', ' testguest ');
  Error occurred during database connection
  if (Mysqli_connect_errno ()) {
    echo ' database connection has occurred. The wrong message is: '. Mysqli_connect_error ();
    Exit ();
  }
  Set the encoding
  $_mysqli->set_charset (' UTF8 ');
  Create three modified SQL statements
  $_sql. = "UPDATE tg_article SET tg_username= ' in Kerala ' WHERE tg_id=1;";
  $_sql. = "UPDATE tg_flower SET tg_fromuser= ' in Kerala ' WHERE tg_id=1;";
  $_sql. = "UPDATE tg_friend SET tg_fromuser= ' ka ' WHERE tg_id=1";
  Methods of using Notification execution
  $_mysqli->multi_query ($_sql);
  Common only way to execute SQL is: $_mysqli->query ($_sql);
  $_mysqli->close ();
? >

demo15.php

<?php header (' content-type:text/html; charset=utf-8; ');
  $_mysqli = new mysqli (' localhost ', ' root ', ' 123456 ', ' testguest ');
    Error occurred during database connection if (Mysqli_connect_errno ()) {echo ' database connection has occurred. The wrong message is: '. Mysqli_connect_error ();
  Exit ();
  //Set up the Code $_mysqli->set_charset (' UTF8 ');
  Create three SELECT statements $_sql. = "SELECT * from Tg_photo;";
  $_sql. = "SELECT * from Tg_user;";
  $_sql. = "SELECT * from Tg_friend";
    if ($_mysqli->multi_query ($_sql)) {//Get the current result set $_result = $_mysqli->store_result ();
    Print_r ($_result->fetch_row ());
    echo ' <br/> ';
    Moves the pointer of the result set to the next $_mysqli->next_result ();
    $_result = $_mysqli->store_result ();
      if (!$_result) {echo ' second SQL statement has five! ';
    Exit ();
    } print_r ($_result->fetch_row ());
    echo ' <br/> ';
    $_mysqli->next_result ();
    $_result = $_mysqli->store_result ();
      if (!$_result) {echo ' third SQL statement has five! ';
    Exit ();
  } print_r ($_result->fetch_row ()); } ElSe {echo ' first SQL statement is incorrect ';
  Exit ();

 } $_mysqli->close ();?>

Demo16.php

<?php header (' content-type:text/html; charset=utf-8; ');
  $_mysqli = new mysqli (' localhost ', ' root ', ' 123456 ', ' testguest ');
    Error occurred during database connection if (Mysqli_connect_errno ()) {echo ' database connection has occurred. The wrong message is: '. Mysqli_connect_error ();
  Exit ();
  //Set up the Code $_mysqli->set_charset (' UTF8 ');
  Set to turn off Autocommit (manually submitted) $_mysqli->autocommit (false);
  Create two SQL statements $_sql. = "UPDATE tg_flower SET tg_flower=tg_flower-50 WHERE tg_id=1;";
  $_sql. = "UPDATE tg_friend SET tg_state=tg_state+50 WHERE tg_id=1";
  Execute multiple SQL statements//As long as the two SQL statements are successful, submit them manually to the database or else, roll back, and undo the previous valid actions. if ($_mysqli->multi_query ($_sql)) {//By the number of rows affected, to determine whether the SQL statement was executed successfully///if $_success is false to indicate that the SQL statement has Wu, then perform a rollback or manually submit $ _success = $_mysqli->affected_rows = = 1?
    True:false;
    Move the pointer down $_mysqli->next_result (); $_success2 = $_mysqli->affected_rows = = 1?
    True:false;
      If both are successful if ($_success && $_success2) {//Execute manual submit $_mysqli->commit ();
    Echo ' perfect submission ';
   } else {   Perform a rollback, undo all previous Operations $_mysqli->rollback (); Echo ' All operations zeroing!
    ';
  } else {echo ' first SQL statement has errors! ';
  //Turn on autocommit $_mysqli->autocommit (true) again;

 $_mysqli->close ();?>

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