Copyright © tutorialspoint.com
The <sql:transaction> tag is used to group <sql:query> and <sql:update> into transactions. You can put as many <sql:query> and <sql:update> as statements inside <sql:transaction> to make them a single transaction.
It ensures that the database modifications performed by the nested actions are either committed or rolled back if an exception is thrown by any nested action.
The <sql:transaction> tag has following attributes:
Attribute | Description | Required | Default |
---|---|---|---|
dataSource | Database connection to use (overrides the default) | No | Default database |
isolation | Transaction isolation (READ_COMMITTED, READ_UNCOMMITTED, REPEATABLE_READ, or SERIALIZABLE) | No | Database’s default |
To start with basic concept, let us create a simple table Students 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 Students ( id int not null, first varchar (255), last varchar (255), dob date ); Query OK, 0 rows affected (0.08 sec) mysql> |
Finally you create few records in Employee table as follows:
mysql> INSERT INTO Students VALUES (100, 'Zara', 'Ali', '2002/05/16'); Query OK, 1 row affected (0.05 sec) mysql> INSERT INTO Students VALUES (101, 'Mahnaz', 'Fatma', '1978/11/28'); Query OK, 1 row affected (0.00 sec) mysql> INSERT INTO Students VALUES (102, 'Zaid', 'Khan', '1980/10/10'); Query OK, 1 row affected (0.00 sec) mysql> INSERT INTO Students VALUES (103, 'Sumit', 'Mittal', '1971/05/08'); Query OK, 1 row affected (0.00 sec) mysql> |
Now let us write a JSP which will make use of <sql:update> along with <sql:transaction> to execute a SQL UPDATE statement. Here code inside <sql:transaction> either would be exeucted completely or not at all:
<%@ page import="java.io.*,java.util.*,java.sql.*"%> <%@ page import="javax.servlet.http.*,javax.servlet.*"%> <%@ page import="java.util.Date,java.text.*" %> <%@ 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:transaction Tag</title> </head> <body> <sql:setDataSource var="snapshot" driver="com.mysql.jdbc.Driver" url="jdbc:mysql://localhost/TEST" user="root" password="cohondob"/> <% Date DoB = new Date("2001/12/16"); int studentId = 100; %> <sql:transaction dataSource="${snapshot}"> <sql:update var="count"> UPDATE Students SET last = 'Ali' WHERE Id = 102 </sql:update> <sql:update var="count"> UPDATE Students SET last = 'Shah' WHERE Id = 103 </sql:update> <sql:update var="count"> INSERT INTO Students VALUES (104,'Nuha', 'Ali', '2010/05/26'); </sql:update> </sql:transaction> <sql:query dataSource="${snapshot}" var="result"> SELECT * from Students; </sql:query> <table border="1" width="100%"> <tr> <th>Emp ID</th> <th>First Name</th> <th>Last Name</th> <th>DoB</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.dob}"/></td> </tr> </c:forEach> </table> </body> </html> |
Now try to access above JSP, which should display the following result:
|
Copyright © tutorialspoint.com