Retrieve data from database by using sql tag of
JSTL SQL library
Here in this section we will see how retrieve data from
database using sql query given by user. To
execute query first create a data source and then execute sql query for that
data source.
| <sql:setDataSource>
: This tag is used to create data source for specified driver, user
name and password of database, url etc. |
Attributes of
the tag <sql:setDataSource>
| dataSource |
Optional attribute
for explicitly specifying their connection factory, it may be a
instance
javax.sql.DataSource interface. |
| driver |
driver
class name that is use to create connection. |
| url |
url associated
with given database. |
| user |
It specifies
user name of the database. |
| password |
It specifies
password of the database. |
| var |
var is a
variable that is used to store created data source. |
| Scope |
Define
the scope for declared variable like page or request or session or
application. |
|
After creating connection to database, now we are
explaining how to execute sql query. To execute sql query we have used a sql tag
<sql:query>, it executes sql and stores result in specified variable.
| <sql:query>
: This tag is used to create data source for specified driver, user
name and password of database, url etc. |
Attributes of
the tag <sql:setDataSource>
| dataSource |
It specifies
that for which data source you want to execute given query. |
| sql |
It
specifies sql query statement. |
| startRow |
The
returned Result object includes the rows starting at the specified
index. |
| maxRows |
specifies max number
of rows in the query result. |
| var |
var is a
variable that is used to store result after execution of given sql
query. |
| Scope |
Define
the scope for declared variable like page or request or session or
application. |
|
Before run this code first create a database named 'mahendra'
and table named 'employee_master' in same database by the sql query given below:
Query to create table:
CREATE TABLE `employee_master` (
`emp_id` int(10) NOT NULL auto_increment,
`firstName` varchar(20) default NULL,
`lastname` varchar(20) default NULL,
`salary` double default NULL,
`tonus` double default NULL,
PRIMARY KEY (`emp_id`)
)
|
Structure of the table:
 |
retrieve_database_SqlJstlTag.jsp
<%@ taglib uri="http://java.sun.com/jstl/core" prefix="c"%>
<%@ taglib uri="http://java.sun.com/jstl/sql" prefix="sql"%>
<sql:setDataSource var="dataSource" driver="com.mysql.jdbc.Driver"
url="jdbc:mysql://localhost:3306/mahendra" user="root" password="root" />
<html>
<head>
<title>Query Example</title>
</head>
<body>
<sql:query var="users" dataSource="${dataSource}">
select* from employee_master;
</sql:query>
<table border=1>
<c:forEach var="row" items="${users.rows}">
<tr>
<td><c:out value="${row.emp_id}" /></td>
<td><c:out value="${row.firstName}" /></td>
<td><c:out value="${row.lastname}" /></td>
<td><c:out value="${row.salary}" /></td>
<td><c:out value="${row.bonus}" /></td>
</tr>
</c:forEach>
</table>
</body>
</html>
|
Steps to run this example :
1: Download the zip file of code and unzip this
file, you will get a folder named 'retrieve_database_SqlJstlTag'.
2: Paste this folder in 'Apache Tomcat 6.0.16-->webapps' or generally
in directory 'C:\apache-tomcat-6.0.16\webapps'.
3: Start tomcat server by click on startup.bat file in
'C:\apache-tomcat-6.0.16\bin'.
4: Open browser and type url 'http://localhost:8080/retrieve_database_SqlJstlTag/retrieve_database_SqlJstlTag.jsp'
or click on this link.
Output of the program
Download Source Code
|
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