在本章中，我们将讨论如何使用JSP访问数据库.我们假设您对JDBC应用程序的工作原理有很好的理解.在通过JSP开始数据库访问之前，请确保您具有正确的JDBC环境设置以及数据库.
有关如何使用JDBC及其环境设置访问数据库的更多详细信息，您可以去通过我们的 JDBC教程.
从基本概念开始，让我们创建一个表格，在该表中创建一些记录，如下所示;
在EMP中创建 Employees 表数据库，使用以下步骤 :
打开命令提示符并切换到安装目录跟随 :
C:\> C:\>cd Program Files\MySQL\bin C:\Program Files\MySQL\bin>
按以下方式登录数据库 :
C:\Program Files\MySQL\bin>mysql -u root -p Enter password: ******** mysql>
在 TEST中创建员工表数据库如下 : :
mysql> use TEST; mysql> create table Employees ( id int not null, age int not null, first varchar (255), last varchar (255) ); Query OK, 0 rows affected (0.08 sec) mysql>
现在让我们在员工表中创建一些记录如下 : :
mysql> INSERT INTO Employees VALUES (100, 18, 'Zara', 'Ali'); Query OK, 1 row affected (0.05 sec) mysql> INSERT INTO Employees VALUES (101, 25, 'Mahnaz', 'Fatma'); Query OK, 1 row affected (0.00 sec) mysql> INSERT INTO Employees VALUES (102, 30, 'Zaid', 'Khan'); Query OK, 1 row affected (0.00 sec) mysql> INSERT INTO Employees VALUES (103, 28, 'Sumit', 'Mittal'); Query OK, 1 row affected (0.00 sec) mysql>
以下示例显示了如何使用 SQL SELECT 语句执行JSP编程中的JTSL :
<%@ page import = "java.io.*,java.util.*,java.sql.*"%>
<%@ page import = "javax.servlet.http.*,javax.servlet.*" %>
<%@ 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>SELECT Operation</title>
</head>
<body>
<sql:setDataSource var = "snapshot" driver = "com.mysql.jdbc.Driver"
url = "jdbc:mysql://localhost/TEST"
user = "root" password = "pass123"/>
<sql:query dataSource = "${snapshot}" var = "result">
SELECT * from Employees;
</sql:query>
<table border = "1" width = "100%">
<tr>
<th>Emp ID</th>
<th>First Name</th>
<th>Last Name</th>
<th>Age</th>
</tr>
<c:forEach var = "row" items = "${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.age}"/></td>
</tr>
</c:forEach>
</table>
</body>
</html>访问上面的JSP，将显示以下结果 :
Emp IDFirst NameLast NameAge100ZaraAli18101MahnazFatma25102ZaidKhan30103SumitMittal28
以下示例显示了如何在JSP编程中使用JTSL执行SQL INSERT语句 :
<%@ page import = "java.io.*,java.util.*,java.sql.*"%>
<%@ page import = "javax.servlet.http.*,javax.servlet.*" %>
<%@ 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>JINSERT Operation</title>
</head>
<body>
<sql:setDataSource var = "snapshot" driver = "com.mysql.jdbc.Driver"
url = "jdbc:mysql://localhost/TEST"
user = "root" password = "pass123"/>
<sql:update dataSource = "${snapshot}" var = "result">
INSERT INTO Employees VALUES (104, 2, 'Nuha', 'Ali');
</sql:update>
<sql:query dataSource = "${snapshot}" var = "result">
SELECT * from Employees;
</sql:query>
<table border = "1" width = "100%">
<tr>
<th>Emp ID</th>
<th>First Name</th>
<th>Last Name</th>
<th>Age</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 = "${row.age}"/></td>
</tr>
</c:forEach>
</table>
</body>
</html>访问上面的JSP，将显示以下结果 :
Emp IDFirst NameLast NameAge100ZaraAli18101MahnazFatma25102ZaidKhan30103SumitMittal28104NuhaAli2
以下示例显示了我们如何执行在JSP编程中使用JTSL的 SQL DELETE 语句 :
<%@ page import = "java.io.*,java.util.*,java.sql.*"%>
<%@ page import = "javax.servlet.http.*,javax.servlet.*" %>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix = "c"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/sql" prefix = "sql"%>
<html>
<head>
<title>DELETE Operation</title>
</head>
<body>
<sql:setDataSource var = "snapshot" driver = "com.mysql.jdbc.Driver"
url = "jdbc:mysql://localhost/TEST"
user = "root" password = "pass123"/>
<c:set var = "empId" value = "103"/>
<sql:update dataSource = "${snapshot}" var = "count">
DELETE FROM Employees WHERE Id = ?
<sql:param value = "${empId}" />
</sql:update>
<sql:query dataSource = "${snapshot}" var = "result">
SELECT * from Employees;
</sql:query>
<table border = "1" width = "100%">
<tr>
<th>Emp ID</th>
<th>First Name</th>
<th>Last Name</th>
<th>Age</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 = "${row.age}"/></td>
</tr>
</c:forEach>
</table>
</body>
</html>访问上面的JSP，将显示以下结果 :
Emp IDFirst NameLast NameAge100ZaraAli18101MahnazFatma25102ZaidKhan30
以下示例显示了我们如何在JSP编程中使用JTSL执行 SQL UPDATE 语句 :
<%@ page import = "java.io.*,java.util.*,java.sql.*"%>
<%@ page import = "javax.servlet.http.*,javax.servlet.*" %>
<%@ taglib uri = "http://java.sun.com/jsp/jstl/core" prefix = "c"%>
<%@ taglib uri = "http://java.sun.com/jsp/jstl/sql" prefix = "sql"%>
<html>
<head>
<title>DELETE Operation</title>
</head>
<body>
<sql:setDataSource var = "snapshot" driver = "com.mysql.jdbc.Driver"
url = "jdbc:mysql://localhost/TEST"
user = "root" password = "pass123"/>
<c:set var = "empId" value = "102"/>
<sql:update dataSource = "${snapshot}" var = "count">
UPDATE Employees SET WHERE last = 'Ali'
<sql:param value = "${empId}" />
</sql:update>
<sql:query dataSource = "${snapshot}" var = "result">
SELECT * from Employees;
</sql:query>
<table border = "1" width = "100%">
<tr>
<th>Emp ID</th>
<th>First Name</th>
<th>Last Name</th>
<th>Age</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.age}"/></td>
</tr>
</c:forEach>
</table>
</body>
</html>访问上面的JSP，将显示以下结果 :
Emp IDFirst NameLast NameAge100ZaraAli18101MahnazFatma25102ZaidAli30
