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The <sql:dateParam> tag is used as a nested action for <sql:query> and <sql:update> supply a date and time value for a value placeholder. If a null value is provided, the value is set to SQL NULL for the placeholder.
The <sql:dateParam> tag has following attributes:
Attribute | Description | Required | Default |
---|---|---|---|
value | Value of the date parameter to set (java.util.Date) | No | Body |
type | DATE (date only), TIME (time only), or TIMESTAMP (date and time) | No | TIMESTAMP |
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:param> and <sql:dataParam> to execute a SQL UPDATE statement to update date of birth for Zara:
<%@ 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:dataParam Tag</title> </head> <body> <sql:setDataSource var="snapshot" driver="com.mysql.jdbc.Driver" url="jdbc:mysql://localhost/TEST" user="root" password="pass123"/> <% Date DoB = new Date("2001/12/16"); int studentId = 100; %> <sql:update dataSource="${snapshot}" var="count"> UPDATE Students SET dob = ? WHERE Id = ? <sql:dateParam value="<%=DoB%>" type="DATE" /> <sql:param value="<%=studentId%>" /> </sql:update> <sql:query dataSource="${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 after updating dob from 2002/05/16 to 2001/12/16 for the record with ID=100:
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