JSTL SQL <sql:transaction> Tag
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.
Attribute:
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 |
Example:
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:
Step 1:
Open a Command Prompt and change to the installation directory as follows:
C:\>
C:\>cd Program Files\MySQL\bin
C:\Program Files\MySQL\bin>
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Step 2:
Login to database as follows
C:\Program Files\MySQL\bin>mysql -u root -p
Enter password: ********
mysql>
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Step 3:
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>
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Create Data Records
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>
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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>
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Now try to access above JSP, which should display the following result:
Emp ID |
First Name |
Last Name |
DoB |
100 |
Zara |
Ali |
2001-12-16 |
101 |
Mahnaz |
Fatma |
1978-11-28 |
102 |
Zaid |
Ali |
1980-10-10 |
103 |
Sumit |
Shah |
1971-05-08 |
104 |
Nuha |
Ali |
2010-05-26 |
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