这是我用于连接到 mySQL 数据库的 Web 应用程序的代码。它应该使用另一页上的下拉菜单显示数据库中一个表的全部内容。我有另一个 .jsp，它使用执行搜索操作的不同 SQL 语句做基本相同的事情，按预期工作。我想如果有的话我会遇到输出 html 表的程序生成问题，但是我得到了 com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException mySQL 语句语法的异常。
<%--
Document : display
Created on : Nov 22, 2018, 11:43:54 AM
Author : Scott
--%>
<%@page import="java.sql.*" %>
<%
try {
Class.forName("com.mysql.jdbc.Driver");
} catch(ClassNotFoundException e) {
System.out.println("Unable to load driver class!");
}
%>
<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Henry Books</title>
</head>
<body>
<h1>Henry Books Store Database Table View </h1>
<%!
public class Table {
String URL = "jdbc:mysql://localhost:3306/HenryBooks?autoReconnect=true&useSSL=false";
String USERNAME = "root";
String PASSWORD = "SAvick4078100";
Connection connection = null;
PreparedStatement viewTable = null;
ResultSet resultSet = null;
public Table(){
try{
connection = DriverManager.getConnection(URL, USERNAME, PASSWORD);
viewTable = connection.prepareStatement(
"SELECT * FROM ?"
);
} catch (SQLException e) {
e.printStackTrace();
}
}
public ResultSet getTable(String tableSelection) {
try{
viewTable.setString(1, tableSelection);
resultSet = viewTable.executeQuery();
} catch (SQLException e) {
e.printStackTrace();
}
return resultSet;
}
}
%>
<%
String tableSelect = new String();
//recieves input value from dropdown menu name "table option" in index.jsp
if(request.getParameter("table option") != null) {
tableSelect = request.getParameter("table option");
}
Table view = new Table();
ResultSet tableView = view.getTable(tableSelect);
ResultSetMetaData rsMetaData = tableView.getMetaData();
int cols = rsMetaData.getColumnCount();
String[] colNames = new String[cols];
for(int i = 0; i < cols; i++) {
colNames[i] = rsMetaData.getColumnName(i+1); //i+1 because the column name index in the ResultSetMetaData begins at 1, not 0
}
%>
<table border="1">
<thead>
<tr>
<% for(int i = 0; i < cols; i++) { %>
<th><%= tableView.getString(colNames[i])%></th>
<% } %>
</tr>
</thead>
<tbody>
<% while(tableView.next()) { %>
<tr>
<% for(int i = 0; i < cols; i++) { %>
<td><%= tableView.getString(colNames[i])%></td>
<% } %>
</tr>
<% } %>
</tbody>
</table>
</body>
</html>
但是，我收到了这些错误消息，我不确定我的 SQL 语法有什么问题。
Severe: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ''Author'' at line 1
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:425)
at com.mysql.jdbc.Util.getInstance(Util.java:408)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:944)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3978)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3914)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2530)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2683)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2495)
at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1903)
at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:2011)
at org.apache.jsp.display_jsp$Table.getTable(display_jsp.java:36)
at org.apache.jsp.display_jsp._jspService(display_jsp.java:113)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:111)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:411)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:473)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:377)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1682)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:318)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:160)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:734)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:673)
at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:99)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:174)
at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:416)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:283)
at com.sun.enterprise.v3.services.impl.ContainerMapper$HttpHandlerCallable.call(ContainerMapper.java:459)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:167)
at org.glassfish.grizzly.http.server.HttpHandler.runService(HttpHandler.java:206)
at org.glassfish.grizzly.http.server.HttpHandler.doHandle(HttpHandler.java:180)
at org.glassfish.grizzly.http.server.HttpServerFilter.handleRead(HttpServerFilter.java:235)
at org.glassfish.grizzly.filterchain.ExecutorResolver$9.execute(ExecutorResolver.java:119)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeFilter(DefaultFilterChain.java:283)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeChainPart(DefaultFilterChain.java:200)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.execute(DefaultFilterChain.java:132)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.process(DefaultFilterChain.java:111)
at org.glassfish.grizzly.ProcessorExecutor.execute(ProcessorExecutor.java:77)
at org.glassfish.grizzly.nio.transport.TCPNIOTransport.fireIOEvent(TCPNIOTransport.java:536)
at org.glassfish.grizzly.strategies.AbstractIOStrategy.fireIOEvent(AbstractIOStrategy.java:112)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.run0(WorkerThreadIOStrategy.java:117)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.access$100(WorkerThreadIOStrategy.java:56)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy$WorkerThreadRunnable.run(WorkerThreadIOStrategy.java:137)
at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:591)
at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.run(AbstractThreadPool.java:571)
at java.lang.Thread.run(Thread.java:748)
Warning: StandardWrapperValve[jsp]: Servlet.service() for servlet jsp threw exception
java.lang.NullPointerException
at org.apache.jsp.display_jsp._jspService(display_jsp.java:114)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:111)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:411)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:473)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:377)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1682)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:318)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:160)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:734)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:673)
at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:99)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:174)
at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:416)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:283)
at com.sun.enterprise.v3.services.impl.ContainerMapper$HttpHandlerCallable.call(ContainerMapper.java:459)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:167)
at org.glassfish.grizzly.http.server.HttpHandler.runService(HttpHandler.java:206)
at org.glassfish.grizzly.http.server.HttpHandler.doHandle(HttpHandler.java:180)
at org.glassfish.grizzly.http.server.HttpServerFilter.handleRead(HttpServerFilter.java:235)
at org.glassfish.grizzly.filterchain.ExecutorResolver$9.execute(ExecutorResolver.java:119)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeFilter(DefaultFilterChain.java:283)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeChainPart(DefaultFilterChain.java:200)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.execute(DefaultFilterChain.java:132)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.process(DefaultFilterChain.java:111)
at org.glassfish.grizzly.ProcessorExecutor.execute(ProcessorExecutor.java:77)
at org.glassfish.grizzly.nio.transport.TCPNIOTransport.fireIOEvent(TCPNIOTransport.java:536)
at org.glassfish.grizzly.strategies.AbstractIOStrategy.fireIOEvent(AbstractIOStrategy.java:112)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.run0(WorkerThreadIOStrategy.java:117)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.access$100(WorkerThreadIOStrategy.java:56)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy$WorkerThreadRunnable.run(WorkerThreadIOStrategy.java:137)
at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:591)
at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.run(AbstractThreadPool.java:571)
at java.lang.Thread.run(Thread.java:748)
最佳答案
使用
"SELECT * FROM ?"
动态添加表名会导致查询
SELECT * FROM 'TABLE_NAME'
而是通过像这样联系字符串来动态附加表名:
"SELECT * FROM "+tableName
其中 tableName 将是字符串类型的变量。
关于Java MySQLSyntaxErrorException？为什么我的 SELECT 语句不正确？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/53437652/