现在有好多初学jsp的网友经常会问数据库怎么连接啊,怎么老出错啊?所以我集中的在这写篇文章供大家参考,其实这种把数据库逻辑全部放在jsp里未必是好的做法,但是有利于初学者学习,所以我就这样做了,当大家学到一定程度的时候,可以考虑用MVC的模式开发。在练习这些代码的时候,你一定将jdbc的驱动程序放到服务器的类路径里,然后要在数据库里建一个表test,有两个字段比如为test1,test2,可以用下面SQL建 create table test(test1 varchar(20),test2 varchar(20),然后向这个表写入一条测试纪录,那么现在开始我们的jsp和数据库之旅吧。
一、jsp连接Oracle8/8i/9i数据库(用thin模式)
testoracle.jsp如下:
String url="jdbc:oracle:thin:@localhost:1521:orcl";
//orcl为你的数据库的SID
String user="scott";
String password="tiger";
Connection conn= DriverManager.getConnection(url,user,password);
Statement stmt=conn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_UPDATABLE);
String sql="select * from test";
ResultSet rs=stmt.executeQuery(sql);
while(rs.next()) {%>
您的第一个字段内容为:
您的第二个字段内容为:
stmt.close();
conn.close();
%>
二、jsp连接Sql Server7.0/2000数据库
testsqlserver.jsp如下:
String url="jdbc:microsoft:sqlserver://localhost:1433;DatabaseName=pubs";
//pubs为你的数据库的
String user="sa";
String password="";
Connection conn= DriverManager.getConnection(url,user,password);
Statement stmt=conn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_UPDATABLE);
String sql="select * from test";
ResultSet rs=stmt.executeQuery(sql);
while(rs.next()) {%>
您的第一个字段内容为:
您的第二个字段内容为:
stmt.close();
conn.close();
%>
三、jsp连接DB2数据库
testdb2.jsp如下:
String url="jdbc:db2://localhost:5000/sample";
//sample为你的数据库名
String user="admin";
String password="";
Connection conn= DriverManager.getConnection(url,user,password);
Statement stmt=conn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_UPDATABLE);
String sql="select * from test";
ResultSet rs=stmt.executeQuery(sql);
while(rs.next()) {%>
您的第一个字段内容为:
您的第二个字段内容为:
stmt.close();
conn.close();
%>
四、jsp连接Informix数据库
testinformix.jsp如下:
String url =
"jdbc:informix-sqli://123.45.67.89:1533/testDB:INFORMIXSERVER=myserver;
user=testuser;password=testpassword";
//testDB为你的数据库名
Connection conn= DriverManager.getConnection(url);
Statement stmt=conn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_UPDATABLE);
String sql="select * from test";
ResultSet rs=stmt.executeQuery(sql);
while(rs.next()) {%>
您的第一个字段内容为:
您的第二个字段内容为:
stmt.close();
conn.close();
%>
五、jsp连接Access数据库
import ="java.util.*"
import ="java.io.*"
import="java.text.*"
contentType="text/html; charset=gb2312"
buffer="20kb"
%>String odbcQuery;
Connection odbcconn;
Statement odbcstmt;
ResultSet odbcrs;
String username,title,content,work,email,url,time,date;
String datetime;
%>
try{
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
}catch (ClassNotFoundException e)
{ out.print ("驱动程序不存在");
}
try{
odbcconn = DriverManager.getConnection("jdbc:odbc:db1");
odbcstmt = odbcconn.createStatement();
odbcQuery="Select * From book where datetime>2001-4-26 Order By datetime DESC";
odbcrs=odbcstmt.executeQuery(odbcQuery);
int i=0;
while (iwhile (odbcrs.next())
{
//*/////////////////////////显示数据库的内容用于调试程序是用//
int ii;
try{
try{
for (ii=1;;ii++)
out.print ("
Cloumn "+ii+" is: "+odbcrs.getString(ii));
}catch (NullPointerException e) {
out.print ("有空的指针");
}
}catch (SQLException e){
}
}
odbcrs.close();
odbcstmt.close();
odbcconn.close();
}catch (SQLException e)
{ out.print (e);
}
%>

MySQL is an open source relational database management system, mainly used to store and retrieve data quickly and reliably. Its working principle includes client requests, query resolution, execution of queries and return results. Examples of usage include creating tables, inserting and querying data, and advanced features such as JOIN operations. Common errors involve SQL syntax, data types, and permissions, and optimization suggestions include the use of indexes, optimized queries, and partitioning of tables.

MySQL is an open source relational database management system suitable for data storage, management, query and security. 1. It supports a variety of operating systems and is widely used in Web applications and other fields. 2. Through the client-server architecture and different storage engines, MySQL processes data efficiently. 3. Basic usage includes creating databases and tables, inserting, querying and updating data. 4. Advanced usage involves complex queries and stored procedures. 5. Common errors can be debugged through the EXPLAIN statement. 6. Performance optimization includes the rational use of indexes and optimized query statements.

MySQL is chosen for its performance, reliability, ease of use, and community support. 1.MySQL provides efficient data storage and retrieval functions, supporting multiple data types and advanced query operations. 2. Adopt client-server architecture and multiple storage engines to support transaction and query optimization. 3. Easy to use, supports a variety of operating systems and programming languages. 4. Have strong community support and provide rich resources and solutions.

InnoDB's lock mechanisms include shared locks, exclusive locks, intention locks, record locks, gap locks and next key locks. 1. Shared lock allows transactions to read data without preventing other transactions from reading. 2. Exclusive lock prevents other transactions from reading and modifying data. 3. Intention lock optimizes lock efficiency. 4. Record lock lock index record. 5. Gap lock locks index recording gap. 6. The next key lock is a combination of record lock and gap lock to ensure data consistency.

The main reasons for poor MySQL query performance include not using indexes, wrong execution plan selection by the query optimizer, unreasonable table design, excessive data volume and lock competition. 1. No index causes slow querying, and adding indexes can significantly improve performance. 2. Use the EXPLAIN command to analyze the query plan and find out the optimizer error. 3. Reconstructing the table structure and optimizing JOIN conditions can improve table design problems. 4. When the data volume is large, partitioning and table division strategies are adopted. 5. In a high concurrency environment, optimizing transactions and locking strategies can reduce lock competition.

In database optimization, indexing strategies should be selected according to query requirements: 1. When the query involves multiple columns and the order of conditions is fixed, use composite indexes; 2. When the query involves multiple columns but the order of conditions is not fixed, use multiple single-column indexes. Composite indexes are suitable for optimizing multi-column queries, while single-column indexes are suitable for single-column queries.

To optimize MySQL slow query, slowquerylog and performance_schema need to be used: 1. Enable slowquerylog and set thresholds to record slow query; 2. Use performance_schema to analyze query execution details, find out performance bottlenecks and optimize.

MySQL and SQL are essential skills for developers. 1.MySQL is an open source relational database management system, and SQL is the standard language used to manage and operate databases. 2.MySQL supports multiple storage engines through efficient data storage and retrieval functions, and SQL completes complex data operations through simple statements. 3. Examples of usage include basic queries and advanced queries, such as filtering and sorting by condition. 4. Common errors include syntax errors and performance issues, which can be optimized by checking SQL statements and using EXPLAIN commands. 5. Performance optimization techniques include using indexes, avoiding full table scanning, optimizing JOIN operations and improving code readability.


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