在mysql中创建表时发生SQLException

Question

在我的项目应用程序中，我动态创建了一个表。我正在使用一个JSP页面从用户接收表值，然后在MySql数据库中通过servlet创建表（通过调用写在java文件中的createTable函数）。

功能在 “CreateTable.java” 创建表：

public void table(String name, String col1, String type1, String null1, String key) throws SQLException { 

    String sql = "CREATE TABLE IF NOT EXISTS ? (id INT NOT NULL AUTO_INCREMENT, ? ? ? , PRIMARY KEY (?))"; 

    PreparedStatement stmt = conn.prepareStatement(sql); 
    stmt.setString(1, "`myDb`."+name); 
    stmt.setString(2, col1); 
    stmt.setString(3, type1); 
    stmt.setString(4, null1); 
    stmt.setString(5, key); 

    stmt.executeUpdate(); 
} 

的Servlet Controller.java：

if (action.equals("createTable")) { 
    String name = request.getParameter("name"); 
    String null3 = request.getParameter("null1"); 
    String type3 = request.getParameter("type1"); 
    String key = request.getParameter("key"); 
    CreateTable createTable = new CreateTable(conn1); 
    try { 
     if (col2 == "" && col3 == "" && col4 == "" && col5 == "" && col6 == "" && col7 == "" && col8 == "" && col9 == "" && col10 == "" && col11 == "" && col12 == "") { 
      createTable.table(name, col1, type1, null1, key); 
      request.getRequestDispatcher("/memberpanel.jsp").forward(request, response); 
      // request.setAttribute("message", ""); 
      response.setContentType("text/html"); 
      out.println("<script type=\"text/javascript\">"); 
      out.println("window.alert('Your table created successfully')"); 
      out.write("setTimeout(function(){window.location.href='memberpanel.jsp'},1000);"); 
      out.write("setTimeout(function(){window.location.href='Index.jsp'},1000);"); 
      out.println("</script>"); 
     } 
    } catch (SQLException e) { 
     // TODO Auto-generated catch block 
     e.printStackTrace(); 
     e.getMessage(); 
    } 

执行时，我收到这样的：

 
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 ''`myDb`.admin' (id INT NOT NULL AUTO_INCREMENT, 'rescue' 'VARCHAR(750)' 'NOT NUL' 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:411) 
    at com.mysql.jdbc.Util.getInstance(Util.java:386) 
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1052) 
    at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4096) 
    at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4028) 
    at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2490) 
    at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2651) 
    at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2683) 
    at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:2144) 
    at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2444) 
    at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2362) 
    at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2347) 
    at org.apache.tomcat.dbcp.dbcp2.DelegatingPreparedStatement.executeUpdate(DelegatingPreparedStatement.java:97) 
    at org.apache.tomcat.dbcp.dbcp2.DelegatingPreparedStatement.executeUpdate(DelegatingPreparedStatement.java:97) 
    at queries.CreateTable.table(CreateTable.java:478) 
    at controller.Controller.doPost(Controller.java:504) 
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:648) 
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729) 
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:292) 
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207) 
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) 
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240) 
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207) 
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:212) 
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106) 
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502) 
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141) 
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79) 
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616) 
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88) 
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:522) 
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1095) 
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:672) 
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1502) 
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1458) 
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) 
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) 
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) 
    at java.lang.Thread.run(Thread.java:745) 

myDb是我的数据库。 admin，rescue，not null，varchar（750），rescue是我的表名，列的测试值。名称，空值或非空值，数据类型和主键。

此外，我试图改变相应的语法，如没有数据库名称和许多东西，但仍然收到相同的错误。 与数据库的连接工作正常。

如果有人可以请帮忙，

在此先感谢。

Answer 1

对于“非值”占位符，不能使用像那样的查询参数。

取而代之的是，在Java中将查询构建为单个字符串，然后执行该字符串。

可以使用String.format()得到类似的东西：

String query = String.format("CREATE TABLE IF NOT EXISTS %s (id INT NOT NULL AUTO_INCREMENT, %s %s %s , PRIMARY KEY (%s))", "`myDb`."+name, col1, type1, null1, key);