Java 类中select语句问题

Question

先看小段代码：
public class a
{
     private int Team_Id;
     public int getTeam_Id() 
     {
return Team_Id;
     }
     public void setTeam_Id(int team_Id) 
     {
Team_Id = team_Id;
     }
     public String execute() throws Exception
     {
         System.out.println(Team_Id);
String sql="select * from Team where Team_Id='Team_Id'";
ResultSet rs=dao.executeQuery(sql);
     }
}
类中Team_Id是int型，表Team中的Team_Id也是int型的。
通过传值可以得到Team_Id=9,后台输出正常。但是在执行上面execute()中的查询时，sql语句就出错。请问应该怎么写那个语句。我已经试过Team_Id='Team_Id'、Team_Id='"+Team_Id+"'、Team_Id=Team_Id。但是都不行。有谁知道吗？谢谢！

Answer 1

ResultSet rs=dao.executeQuery(sql); 
--------------------------------------
dao是什么？

Answer 2

String sql="select * from Team where Team_Id="+Team_Id; 

Answer 3

String sql="select * from Team where Team_Id="+Team_Id; 

Answer 4

执行是的语句应该是主函数：
public static void main(string[]args){}加上你想实现的内容你可以试试！

Answer 5

dao是个类对象，上面没有写出来，是我专门写的操作数据库的类。
String sql="select * from Team where Team_Id="+Team_Id; 这样有错吧！

Answer 6

JDBC  基础题呀，    看看.....sql 语句String sql="select * from Team where Team_Id='"+Team_Id+"'"; Connection conn = null;
Statement sta = null;
ResultSet rs = null;
try {
conn = JDBCAccess.getConnection(); // 得到一个连接
sta = DriverManager.getConnection("url","user","youpassword");
rs = JDBCAccess.searchSQL(sta, sql);

if(rs!=null){

   while (rs.next()) {
  // 你要得到的列
   
   }
   }
} catch (Exception e) {
e.printStackTrace();
}finally{
if(rs!=null){
try {
rs.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
if(sta!=null){
try {
sta.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
try {
if(conn!=null && !conn.isClosed()){
conn.close();
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}试试

Answer 7

conn = JDBCAccess.getConnection(); 将这改 成你得到链接的方法
 

Answer 8

晕菜，忘记改了点东西rs = sta .executeQuery(sql);呵呵....

Answer 9

这样写结果就是：
ResultSet rs=dao.executeQuery("select * from Team where Team_Id=9");
没明白你DAO是类对象的含义

Answer 10

Connection  cn;
cn=Dbconect.Getcon();
String str="select * from Team where Team_Id=?";
PreparedStatement ps=cn.prepareStatement(str);
ps.setString(1, Team_Id);
ResultSet rs=ps.executeQuery();
------------------------------------------------
自己看去！

Answer 11

回7楼，这个我知道，我在另外的文件中专门写成了实现这些的类。而且在其他地方可以正确运行，不过一般是
public String a(int a)
{
    String sql="select * from Team where Team_Id='"+a+"'"; 
    return "ssss";
}
这种类型的就可以！回10楼：
那样还是有错，和写成String sql="select * from Team where Team_Id='"+Team_Id+"'"; 一样的错。错误提示：
com.microsoft.sqlserver.jdbc.SQLServerException: ????????? 
    com.microsoft.sqlserver.jdbc.SQLServerException.makeFromDriverError(Unknown Source)
    com.microsoft.sqlserver.jdbc.SQLServerResultSet.verifyResultSetHasCurrentRow(Unknown Source)
    com.microsoft.sqlserver.jdbc.SQLServerResultSet.getterGetColumn(Unknown Source)
    com.microsoft.sqlserver.jdbc.SQLServerResultSet.getInt(Unknown Source)
    com.microsoft.sqlserver.jdbc.SQLServerResultSet.getInt(Unknown Source)

Answer 12

public String a(int a) 
{ 
    String sql="select * from Team where Team_Id='"+a+"'"; 
    return "ssss"; 
} 
--------------------------------------------------------------------
没执行sql语句怎么写都是返回SSSS，根本没用.
String sql="select * from Team where Team_Id="+Team_Id;
怎么不试上面这条。

Answer 13

回13楼，当然我本来的类中是写了执行的，还去结果了，我只是为了方便看，把其他的都省略了。
String sql="select * from Team where Team_Id="+Team_Id; 这句我也试过了，和
String sql="select * from Team where Team_Id='"+Team_Id+"'"; 这句是一样的错误提示。

Answer 14

String sql="select * from Team where Team_Id="+Team_Id; 或是
String sql="select * from Team where Team_Id='"+Team_Id + "'"; 

Answer 15

String sql="select * from Team where Team_Id="+Team_Id+"";

Answer 16

String sql="select * from Team where Team_Id='Team_Id'"; 电脑执行的是  select * from Team where Team_Id ='Team_Id'；改成： String sql="select * from Team where Team_Id ="+Team_Id;电脑执行的才是  :  select * from Team where Team_Id = 9;

Answer 17

晕死，
com.microsoft.sqlserver.jdbc.SQLServerException: ????????? 
    com.microsoft.sqlserver.jdbc.SQLServerException.makeFromDriverError(Unknown Source) 
这个错误你怎么知道是那句SQL的问题。。
把你的所有错误信息贴出来吧

Answer 18

'Team_Id'这个在数据库是字符串，当然执行select * from Team where Team_Id ='Team_Id'；如果你想select * from Team where Team_Id ='9'；
那写成String sql="select * from Team where Team_Id='"+Team_Id+"'";

Answer 19

我在后台做了输出标记，就是执行到那句时，下面的输出标记都没有输出，所以觉得是那句出错了。错误提示：
com.microsoft.sqlserver.jdbc.SQLServerException: ????????? 
    com.microsoft.sqlserver.jdbc.SQLServerException.makeFromDriverError(Unknown Source)
    com.microsoft.sqlserver.jdbc.SQLServerResultSet.verifyResultSetHasCurrentRow(Unknown Source)
    com.microsoft.sqlserver.jdbc.SQLServerResultSet.getterGetColumn(Unknown Source)
    com.microsoft.sqlserver.jdbc.SQLServerResultSet.getInt(Unknown Source)
    com.microsoft.sqlserver.jdbc.SQLServerResultSet.getInt(Unknown Source)
    entertainment.game.action.JoinEmTeamAction.execute(JoinEmTeamAction.java:66)
    sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    java.lang.reflect.Method.invoke(Unknown Source)
    com.opensymphony.xwork2.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:440)
    com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:279)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:242)
    com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:163)
    com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236)
    com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:249)
    org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:68)
    com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236)
    com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:122)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236)
    com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:195)
    com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236)
    com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:195)
    com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236)
    com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:148)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236)
    org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:93)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236)
    org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:235)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236)
    com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java:89)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236)
    com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.java:128)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236)
    org.apache.struts2.interceptor.ProfilingActivationInterceptor.intercept(ProfilingActivationInterceptor.java:104)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236)
    org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java:267)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236)
    com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java:126)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236)
    com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept(PrepareInterceptor.java:138)
    com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236)
    com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept(I18nInterceptor.java:148)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236)
    org.apache.struts2.interceptor.ServletConfigInterceptor.intercept(ServletConfigInterceptor.java:164)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236)
    com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java:128)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236)
    com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:176)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236)
    org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:52)
    org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:468)
    org.apache.struts2.dispatcher.FilterDispatcher.doFilter(FilterDispatcher.java:395)
    org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
    org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
    org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
    org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
    org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
    org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
    org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
    org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:849)
    org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)
    org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:454)
    java.lang.Thread.run(Unknown Source)

Answer 20

dao   的代码是这样的。package dao;import java.sql.*;
import java.util.*;import news.entity.*;public class DAO 
{
Connection conn=null;
Statement stmt=null;
ResultSet rs=null;
public void DriverDB()
{
try
{
Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
}
catch(Exception e)
{
System.out.println("000");
e.printStackTrace();
}
}

public ResultSet executeQuery(String sql)
{
try
{
conn=DriverManager.getConnection("jdbc:sqlserver://localhost:1433;DatabaseName=Struts2_scu","sa","111");
         stmt=conn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_READ_ONLY);
         rs=stmt.executeQuery(sql);
}
catch(SQLException e)
{
e.printStackTrace();
}
return rs;
}

public void executeUpdate(String sql)
{
try
{
conn=DriverManager.getConnection("jdbc:sqlserver://localhost:1433; DatabaseName=Struts2_scu","sa","111");
         stmt=conn.createStatement();
         stmt.executeUpdate(sql);
}
catch(SQLException e)
{
e.printStackTrace();
}
}

public void close()
{
try {
rs.close();
} catch (Exception e) {
e.printStackTrace();
}

try {
stmt.close();
} catch (Exception e) {
e.printStackTrace();
}

try {
conn.close();
} catch (Exception e) {
e.printStackTrace();
}
}}

Answer 21

String sql="select * from Team where Team_Id="+Team_Id

Answer 22

entertainment.game.action.JoinEmTeamAction.execute(JoinEmTeamAction.java:66)
JoinEmTeamAction的66行
这里是什么东西？

Answer 23

另外这里
static{
Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver"); 
 conn=DriverManager.getConnection("jdbc:sqlserver://localhost:1433; DatabaseName=Struts2_scu","sa","111"); 
}
写一个静态块，没必要每个方法都写