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How to group queries using transaction in a JSP?
The <sql:transaction> tag is used to group the <sql:query> and <sql:update> tags into transactions. You can put as many <sql:query> and <sql:update> tags as statements inside the <sql:transaction> tag to create 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 the 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 the basic concept, let us create a Students table in the TEST database and create a 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>
Step 2
Login to the database as follows −
C:\Program Files\MySQL\bin>mysql -u root -p Enter password: ******** mysql>
Step 3
Create the Employee table in the 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>Create Data Records
We will now create a few records in the 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>
Let us now write a JSP which will make use of the <sql:update> tag along with <sql:transaction> tag to execute an SQL UPDATE statement. Here the code inside <sql:transaction> tag either will be executed 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>Access the above JSP, the following result will be displayed −
+-------------+----------------+-----------------+-----------------+ | 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 | Mittal | 1971-05-08 | | 104 | Nuha | Ali | 2010-05-26 | +-------------+----------------+-----------------+-----------------+
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