programming php

Làm cách nào để tìm nạp chỉ một bản ghi trong PHP?

Các thao tác cơ sở dữ liệu trong PHP là một điều rất quan trọng, đặc biệt cần thiết trong các thao tác CRUD (Tạo, Đọc, Cập nhật và Xóa)

Trong bài viết này, chúng ta sẽ thảo luận về Đọc phần i. e. lấy dữ liệu từ cơ sở dữ liệu

Có hai cách để kết nối với cơ sở dữ liệu bằng PHP. Chúng như sau

MySQLi (“i” là viết tắt của cải tiến)
PDO (Đối tượng dữ liệu PHP)

MySQLi so với PDO. Cả hai cách đều thực sự tốt nhưng chỉ có một điểm khác biệt giữa hai phương pháp, PDO có thể hoạt động trên 12 hệ thống cơ sở dữ liệu khác nhau trong khi MySQLi chỉ hoạt động với cơ sở dữ liệu MySQL

Kết nối với cơ sở dữ liệu

Hướng đối tượng MySQLi
$conn = new mysqli($servername, $username, $databasename)
Thủ tục MySQLi
$conn = mysqli_connect($servername, $username, $password, $databasename);
PDO
$conn = new PDO("mysql:host=$servername;dbname=myDB", $username, $password, $databasename);

Thực hiện truy vấn. Sau khi kết nối với cơ sở dữ liệu, chúng ta cần chạy các truy vấn để tìm nạp dữ liệu. Trong hoạt động Đọc, chúng tôi sẽ chỉ sử dụng các truy vấn được chọn để tìm nạp dữ liệu từ cơ sở dữ liệu

Hướng đối tượng MySQLi
$conn->query($query);
Thủ tục MySQLi
mysqli_query($conn, $query)
PDO
$stmt = $conn->prepare($query); $stmt->execute();

Đóng kết nối. Sau khi quá trình tìm nạp được thực hiện, bạn nên đóng kết nối tới cơ sở dữ liệu bằng hàm close()

$conn->close();

Cơ sở dữ liệu mẫu

Tạo Table trong cơ sở dữ liệu

CREATE TABLE `Student Details` ( `Roll_No` int(11) NOT NULL, `Name` varchar(255) NOT NULL, `City` varchar(255) NOT NULL, `Age` int(11) NOT NULL, PRIMARY KEY (`Roll_No`) );

Chi tiết sinh viên

Cách tiếp cận hướng đối tượng MySQLi

Mã PHP

PHP

$conn = mysqli_connect($servername, $username, $password, $databasename);1

$conn = mysqli_connect($servername, $username, $password, $databasename);2

$conn = mysqli_connect($servername, $username, $password, $databasename);3_______1_______4 $conn = mysqli_connect($servername, $username, $password, $databasename);5$conn = mysqli_connect($servername, $username, $password, $databasename);6$conn = mysqli_connect($servername, $username, $password, $databasename);7

$conn = mysqli_connect($servername, $username, $password, $databasename);3_______1_______9 $conn = mysqli_connect($servername, $username, $password, $databasename);5$conn = new PDO("mysql:host=$servername;dbname=myDB", $username, $password, $databasename);1$conn = mysqli_connect($servername, $username, $password, $databasename);7

$conn = mysqli_connect($servername, $username, $password, $databasename);3_______2_______4 $conn = mysqli_connect($servername, $username, $password, $databasename);5$conn = new PDO("mysql:host=$servername;dbname=myDB", $username, $password, $databasename);6$conn = mysqli_connect($servername, $username, $password, $databasename);7

$conn = mysqli_connect($servername, $username, $password, $databasename);3_______2_______9 $conn = mysqli_connect($servername, $username, $password, $databasename);5$conn->query($query);1$conn = mysqli_connect($servername, $username, $password, $databasename);7

$conn = mysqli_connect($servername, $username, $password, $databasename);2

$conn = mysqli_connect($servername, $username, $password, $databasename);3_______3_______5

$conn = mysqli_connect($servername, $username, $password, $databasename);3_______3_______7 $conn = mysqli_connect($servername, $username, $password, $databasename);5$conn->query($query);9 mysqli_query($conn, $query)0$conn = mysqli_connect($servername, $username, $password, $databasename);4mysqli_query($conn, $query)2

mysqli_query($conn, $query)3$conn = mysqli_connect($servername, $username, $password, $databasename);9mysqli_query($conn, $query)2_______2_______4mysqli_query($conn, $query)2$conn = new PDO("mysql:host=$servername;dbname=myDB", $username, $password, $databasename);9mysqli_query($conn, $query)9

$conn = mysqli_connect($servername, $username, $password, $databasename);2

$conn = mysqli_connect($servername, $username, $password, $databasename);3_______5_______2

$conn = mysqli_connect($servername, $username, $password, $databasename);3_______5_______4 $stmt = $conn->prepare($query); $stmt->execute();5_______3_______7_______5_______7

$stmt = $conn->prepare($query); $stmt->execute();8_______5_______9$stmt = $conn->prepare($query); $stmt->execute();5_______6_______1 $conn->close();2$conn->query($query);7_______6_______4

$conn = mysqli_connect($servername, $username, $password, $databasename);3_______6_______6

$conn = mysqli_connect($servername, $username, $password, $databasename);2

$conn = mysqli_connect($servername, $username, $password, $databasename);3_______6_______9

$conn = mysqli_connect($servername, $username, $password, $databasename);3_______7_______1 $conn = mysqli_connect($servername, $username, $password, $databasename);5CREATE TABLE `Student Details` ( `Roll_No` int(11) NOT NULL, `Name` varchar(255) NOT NULL, `City` varchar(255) NOT NULL, `Age` int(11) NOT NULL, PRIMARY KEY (`Roll_No`) );3_______1_______7

$conn = mysqli_connect($servername, $username, $password, $databasename);2

$conn = mysqli_connect($servername, $username, $password, $databasename);3_______7_______7

$conn = mysqli_connect($servername, $username, $password, $databasename);3_______7_______9 $conn = mysqli_connect($servername, $username, $password, $databasename);5$conn->query($query);7Roll No: 1 - Name: Ram | City: Delhi | Age: 18 Roll No: 2 - Name: Shyam | City: Mumbai | Age: 19 Roll No: 3 - Name: Rohit | City: Chennai | Age: 18 Roll No: 4 - Name: Suresh | City: Kolkata | Age: 202CREATE TABLE `Student Details` ( `Roll_No` int(11) NOT NULL, `Name` varchar(255) NOT NULL, `City` varchar(255) NOT NULL, `Age` int(11) NOT NULL, PRIMARY KEY (`Roll_No`) );1mysqli_query($conn, $query)9

$conn = mysqli_connect($servername, $username, $password, $databasename);2

mysqli_query($conn, $query)3$stmt = $conn->prepare($query); $stmt->execute();4 $stmt = $conn->prepare($query); $stmt->execute();5CREATE TABLE `Student Details` ( `Roll_No` int(11) NOT NULL, `Name` varchar(255) NOT NULL, `City` varchar(255) NOT NULL, `Age` int(11) NOT NULL, PRIMARY KEY (`Roll_No`) );9Roll No: 1 - Name: Ram Roll No: 2 - Name: Shyam Roll No: 3 - Name: Rohit Roll No: 4 - Name: Suresh0

mysqli_query($conn, $query)3____87_______2

Roll No: 1 - Name: Ram Roll No: 2 - Name: Shyam Roll No: 3 - Name: Rohit Roll No: 4 - Name: Suresh3Roll No: 1 - Name: Ram Roll No: 2 - Name: Shyam Roll No: 3 - Name: Rohit Roll No: 4 - Name: Suresh4

Roll No: 1 - Name: Ram Roll No: 2 - Name: Shyam Roll No: 3 - Name: Rohit Roll No: 4 - Name: Suresh3Roll No: 1 - Name: Ram Roll No: 2 - Name: Shyam Roll No: 3 - Name: Rohit Roll No: 4 - Name: Suresh6$stmt = $conn->prepare($query); $stmt->execute();5Roll No: 1 - Name: Ram Roll No: 2 - Name: Shyam Roll No: 3 - Name: Rohit Roll No: 4 - Name: Suresh8 $conn = mysqli_connect($servername, $username, $password, $databasename);5CREATE TABLE `Student Details` ( `Roll_No` int(11) NOT NULL, `Name` varchar(255) NOT NULL, `City` varchar(255) NOT NULL, `Age` int(11) NOT NULL, PRIMARY KEY (`Roll_No`) );9$conn = mysqli_connect($servername, $username, $password, $databasename);01

Roll No: 1 - Name: Ram Roll No: 2 - Name: Shyam Roll No: 3 - Name: Rohit Roll No: 4 - Name: Suresh3____87_______2

$conn = mysqli_connect($servername, $username, $password, $databasename);04_______1_______05 $conn = mysqli_connect($servername, $username, $password, $databasename);06 $conn->close();2

$conn = mysqli_connect($servername, $username, $password, $databasename);08Roll No: 1 - Name: Ram Roll No: 2 - Name: Shyam Roll No: 3 - Name: Rohit Roll No: 4 - Name: Suresh8$conn = mysqli_connect($servername, $username, $password, $databasename);10_______1_______11$conn = mysqli_connect($servername, $username, $password, $databasename);12$conn = mysqli_connect($servername, $username, $password, $databasename);13 $conn->close();2

$conn = mysqli_connect($servername, $username, $password, $databasename);08Roll No: 1 - Name: Ram Roll No: 2 - Name: Shyam Roll No: 3 - Name: Rohit Roll No: 4 - Name: Suresh8$conn = mysqli_connect($servername, $username, $password, $databasename);10_______1_______18$conn = mysqli_connect($servername, $username, $password, $databasename);12$conn = mysqli_connect($servername, $username, $password, $databasename);20 $conn = mysqli_connect($servername, $username, $password, $databasename);21

$conn = mysqli_connect($servername, $username, $password, $databasename);08Roll No: 1 - Name: Ram Roll No: 2 - Name: Shyam Roll No: 3 - Name: Rohit Roll No: 4 - Name: Suresh8$conn = mysqli_connect($servername, $username, $password, $databasename);10_______1_______25$conn = mysqli_connect($servername, $username, $password, $databasename);12$conn = mysqli_connect($servername, $username, $password, $databasename);27 $conn = mysqli_connect($servername, $username, $password, $databasename);21

$conn = mysqli_connect($servername, $username, $password, $databasename);08Roll No: 1 - Name: Ram Roll No: 2 - Name: Shyam Roll No: 3 - Name: Rohit Roll No: 4 - Name: Suresh8$conn = mysqli_connect($servername, $username, $password, $databasename);10$conn = mysqli_connect($servername, $username, $password, $databasename);32$conn = mysqli_connect($servername, $username, $password, $databasename);12$conn = mysqli_connect($servername, $username, $password, $databasename);34$conn = mysqli_connect($servername, $username, $password, $databasename);7

Roll No: 1 - Name: Ram Roll No: 2 - Name: Shyam Roll No: 3 - Name: Rohit Roll No: 4 - Name: Suresh3_______6_______6

mysqli_query($conn, $query)3$conn = mysqli_connect($servername, $username, $password, $databasename);39

mysqli_query($conn, $query)3$conn = mysqli_connect($servername, $username, $password, $databasename);41 Roll No: 1 - Name: Ram Roll No: 2 - Name: Shyam Roll No: 3 - Name: Rohit Roll No: 4 - Name: Suresh2

Roll No: 1 - Name: Ram Roll No: 2 - Name: Shyam Roll No: 3 - Name: Rohit Roll No: 4 - Name: Suresh3$conn = mysqli_connect($servername, $username, $password, $databasename);05 $conn = mysqli_connect($servername, $username, $password, $databasename);45$conn = mysqli_connect($servername, $username, $password, $databasename);7

mysqli_query($conn, $query)3_______6_______6

$conn = mysqli_connect($servername, $username, $password, $databasename);2

$conn = mysqli_connect($servername, $username, $password, $databasename);50$conn->query($query);7$conn = mysqli_connect($servername, $username, $password, $databasename);52

$conn = mysqli_connect($servername, $username, $password, $databasename);2

$conn = mysqli_connect($servername, $username, $password, $databasename);54

đầu ra

Phương pháp thủ tục MySQLi

Mã PHP

PHP

$conn = mysqli_connect($servername, $username, $password, $databasename);1

$conn = mysqli_connect($servername, $username, $password, $databasename);2

$conn = mysqli_connect($servername, $username, $password, $databasename);3_______3_______5

$conn = mysqli_connect($servername, $username, $password, $databasename);3_______3_______7 $conn = mysqli_connect($servername, $username, $password, $databasename);82$conn = mysqli_connect($servername, $username, $password, $databasename);4_______1_______84

$conn = mysqli_connect($servername, $username, $password, $databasename);2

$conn = mysqli_connect($servername, $username, $password, $databasename);3_______5_______2

$conn = mysqli_connect($servername, $username, $password, $databasename);3_______5_______4 $conn = mysqli_connect($servername, $username, $password, $databasename);97_______3_______7_______1_______99

$stmt = $conn->prepare($query); $stmt->execute();8_______5_______9_______5_______5$conn->close();1 $conn = new PDO("mysql:host=$servername;dbname=myDB", $username, $password, $databasename);04

$conn = mysqli_connect($servername, $username, $password, $databasename);3_______6_______6

$conn = mysqli_connect($servername, $username, $password, $databasename);2

$conn = mysqli_connect($servername, $username, $password, $databasename);3_______6_______9

$conn = mysqli_connect($servername, $username, $password, $databasename);3_______7_______1 $conn = mysqli_connect($servername, $username, $password, $databasename);5$conn = new PDO("mysql:host=$servername;dbname=myDB", $username, $password, $databasename);13$conn = mysqli_connect($servername, $username, $password, $databasename);7

$conn = mysqli_connect($servername, $username, $password, $databasename);3_______7_______7

$conn = mysqli_connect($servername, $username, $password, $databasename);3_______7_______9 $conn = new PDO("mysql:host=$servername;dbname=myDB", $username, $password, $databasename);19_______3_______7mysqli_query($conn, $query)2CREATE TABLE `Student Details` ( `Roll_No` int(11) NOT NULL, `Name` varchar(255) NOT NULL, `City` varchar(255) NOT NULL, `Age` int(11) NOT NULL, PRIMARY KEY (`Roll_No`) );1mysqli_query($conn, $query)9

$conn = mysqli_connect($servername, $username, $password, $databasename);2

$conn = mysqli_connect($servername, $username, $password, $databasename);3_______5_______4 $conn = new PDO("mysql:host=$servername;dbname=myDB", $username, $password, $databasename);27CREATE TABLE `Student Details` ( `Roll_No` int(11) NOT NULL, `Name` varchar(255) NOT NULL, `City` varchar(255) NOT NULL, `Age` int(11) NOT NULL, PRIMARY KEY (`Roll_No`) );9$conn = new PDO("mysql:host=$servername;dbname=myDB", $username, $password, $databasename);29

$stmt = $conn->prepare($query); $stmt->execute();8_______87_______4

$stmt = $conn->prepare($query); $stmt->execute();8_______87_______6$stmt = $conn->prepare($query); $stmt->execute();5Roll No: 1 - Name: Ram Roll No: 2 - Name: Shyam Roll No: 3 - Name: Rohit Roll No: 4 - Name: Suresh8 $conn = new PDO("mysql:host=$servername;dbname=myDB", $username, $password, $databasename);36CREATE TABLE `Student Details` ( `Roll_No` int(11) NOT NULL, `Name` varchar(255) NOT NULL, `City` varchar(255) NOT NULL, `Age` int(11) NOT NULL, PRIMARY KEY (`Roll_No`) );9$conn = new PDO("mysql:host=$servername;dbname=myDB", $username, $password, $databasename);38

$conn = new PDO("mysql:host=$servername;dbname=myDB", $username, $password, $databasename);39_______1_______05 $conn = mysqli_connect($servername, $username, $password, $databasename);06 $conn->close();2Roll No: 1 - Name: Ram Roll No: 2 - Name: Shyam Roll No: 3 - Name: Rohit Roll No: 4 - Name: Suresh8$conn = mysqli_connect($servername, $username, $password, $databasename);10$conn = mysqli_connect($servername, $username, $password, $databasename);11$conn = new PDO("mysql:host=$servername;dbname=myDB", $username, $password, $databasename);46

$conn = new PDO("mysql:host=$servername;dbname=myDB", $username, $password, $databasename);39_______6_______2$conn = mysqli_connect($servername, $username, $password, $databasename);13 $conn->close();2_______87_______8$conn = mysqli_connect($servername, $username, $password, $databasename);10$conn = mysqli_connect($servername, $username, $password, $databasename);18$conn = mysqli_connect($servername, $username, $password, $databasename);12$conn = mysqli_connect($servername, $username, $password, $databasename);34$conn = mysqli_connect($servername, $username, $password, $databasename);7

$stmt = $conn->prepare($query); $stmt->execute();8_______6_______6

$conn = mysqli_connect($servername, $username, $password, $databasename);3_______6_______6$conn = mysqli_connect($servername, $username, $password, $databasename);41 Roll No: 1 - Name: Ram Roll No: 2 - Name: Shyam Roll No: 3 - Name: Rohit Roll No: 4 - Name: Suresh2

$stmt = $conn->prepare($query); $stmt->execute();8_______1_______05 $conn = mysqli_connect($servername, $username, $password, $databasename);45$conn = mysqli_connect($servername, $username, $password, $databasename);7

$conn = mysqli_connect($servername, $username, $password, $databasename);3_______6_______6

$conn = mysqli_connect($servername, $username, $password, $databasename);2

$conn = mysqli_connect($servername, $username, $password, $databasename);3_______3_______7$conn = mysqli_connect($servername, $username, $password, $databasename);52

$conn = mysqli_connect($servername, $username, $password, $databasename);2

$conn = mysqli_connect($servername, $username, $password, $databasename);54

đầu ra

Roll No: 1 - Name: Ram Roll No: 2 - Name: Shyam Roll No: 3 - Name: Rohit Roll No: 4 - Name: Suresh

Phương pháp tiếp cận PDO