JSP Database Connection JSP Standard Tag Library (JSTL)

<sql:update> tag

The <sql:update> tag is used to execute an SQL statement that does not return a value, such as SQL INSERT, UPDATE, DELETE statements.

Syntax format

<sql:update var="<string>" scope="<string>" sql="<string>" dataSource="<string>"/>

Attribute

The <sql:update> tag has the following attributes:

Attribute	Description	Is it necessary	Default value
sql	The SQL command to be executed (does not return a ResultSet object)	No	Body
dataSource	The database connection used (overriding the default value)	No	Default database
var	Used to store the number of affected rows	No	None
scope	The scope of the var attribute	No	Page

　　 Program Example

Firstly, you need to create an Employees table in the TEST database, and then add several records to the table. The specific steps are as follows:

　　 Steps1:

Open CMD, change the directory to the installation directory:

C:\>
C:\>cd Program Files\MySQL\bin
C:\Program Files\MySQL\bin>

　　 Steps2:

C:\Program Files\MySQL\bin>mysql　-u root　-p
Enter password:　********
mysql>

　　 Steps3:

Establish the Employees table in the TEST database:

mysql> use TEST;
mysql> create table Employees
　　　　(
　　　　　id int not null,
　　　　　age int not null,
　　　　　first varchar (255),
　　　　　last varchar (255)
　　　　);
Query OK, 0 rows affected (0.08　sec)
mysql>

　　 Create data records:

Finally, create several records in the Employees table:

mysql> INSERT INTO Employees VALUES (100,　18, 'Zara', 'Ali');
Query OK,　1　row affected (0.05　sec)
　
mysql> INSERT INTO Employees VALUES (101,　25, 'Mahnaz', 'Fatma');
Query OK,　1　row affected (0.00 sec)
　
mysql> INSERT INTO Employees VALUES (102,　30, 'Zaid', 'Khan');
Query OK,　1　row affected (0.00 sec)
　
mysql> INSERT INTO Employees VALUES (103,　28, 'Sumit', 'Mittal');
Query OK,　1　row affected (0.00 sec)
　
mysql>

Now, write a JSP file to use the <sql:update> tag to execute SQL INSERT statements:

<%@ page language="java" contentType="text/html; charset=UTF-8"
　　　　pageEncoding="UTF-8"%>
<%@ page import="java.io.*,java.util.*,java.sql.*"%>
<%@ page import="javax.servlet.http.*,javax.servlet.*" %>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/sql" prefix="sql"%>
<html>
<head>
<title>JSTL sql:update tag</title>
</head>
<body>
　
<sql:setDataSource var="snapshot" driver="com.mysql.jdbc.Driver">
　　　　　url="jdbc:mysql://localhost/TEST"
　　　　　user="root" password="pass123"/>
<sql:update dataSource="${snapshot}" var="count">
　　　INSERT INTO Employees VALUES (104,　2, 'Nuha', 'Ali');
</sql:update>
<sql:query dataSource="${snapshot}" var="result">
　　　SELECT　*　from Employees;
</sql:query>
　
<table border="1" width="100%">
<tr>
<th>Emp ID</th>
<th>First Name</th>
<th>Last Name</th>
<th>Age</th>
</tr>
<c:forEach var="row" items="${result.rows}">
<tr>
<td><c:out value="${row.id}"/></td>
<td><c:out value="${row.first}"/></td>
<td><c:out value="${row.last}"/></td>
<td><c:out value="${row.age}"/></td>
</tr>
</c:forEach>
</table>
</body>
</html>

The running result is as follows:

The usage of SQL UPDATE and DELETE statements is similar to that of INSERT statements.

You can use variables in sql:update if needed sql:param.

<sql:update dataSource="${snapshot}" var="count">
　　DELETE FROM Employees WHERE Id = ?
　　<sql:param value="${empId}"　/>
</sql:update>

JSP Standard Tag Library