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The <sql:update> tag executes an SQL statement that does not return data, for example SQL INSERT, UPDATE, or DELETE statements.
The <sql:update> tag has following attributes:
Attribute | Description | Required | Default |
---|---|---|---|
sql | SQL command to execute (should not return a ResultSet) | No | Body |
dataSource | Database connection to use (overrides the default) | No | Default database |
var | Name of the variable to store the count of affected rows | No | None |
scope | Scope of the variable to store the count of affected rows | No | Page |
To start with basic concept, let us create a simple table Employees table in TEST database and create few records in that table as follows:
Open a Command Prompt and change to the installation directory as follows:
C:\> C:\>cd Program Files\MySQL\bin C:\Program Files\MySQL\bin> |
Login to database as follows
C:\Program Files\MySQL\bin>mysql -u root -p Enter password: ******** mysql> |
Create the table Employee in TEST database as follows:
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> |
Finally you create few records in Employee table as follows:
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 let us write a JSP which will make use of <sql:update> to execute a SQL INSERT statement to create one record in the table as follows:
<%@ 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> |
Now try to access above JSP, which should display the following result:
|
Similar way, you can try SQL UPDATE and DELETE statements on the same table.
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