无法使用数据源连接执行多个 SQL 查询答案

【问题标题】：Unable to execute multiple SQL queries with Data Source connection无法使用数据源连接执行多个 SQL 查询
【发布时间】：2014-12-21 19:35:41
【问题描述】：

我正在尝试执行多个查询，但只有部分查询被执行。

这是我的代码：

public class PostPrReqDaoImpl implements PostPrReqDaoInterface {

    @Override
    public boolean validate(PostPrReqBean pprb1,PostPrReqBean pprb2,PostPrReqBean pprb3,PostPrReqBean pprb4) {
        System.out.println("Inside PostPrReq Dao");
        int resstat=1;
        //snuname,snuusrname,snupass,snuempid,snuemail,snudob,snuskill,snuexp,snudesg;
        java.io.PrintWriter out = null;
        try {
            out = pprb1.getBeanresponse().getWriter();
        } catch (IOException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }
        pprb1.getBeanresponse().setContentType("text/html");



        try {
            /* get the DataSource from using the JNDI name */
            Class.forName("com.mysql.jdbc.Driver");
            InitialContext ctx = new InitialContext();
            DataSource ds = (DataSource)ctx.lookup("java:comp/env/jdbc/Test");
            //username, pass,name, id,dob ,skillset, exp,designation ,email
            //Create connection and then continue as usual other JDBC calls 
            Connection conn=ds.getConnection();
            System.out.println("Connection succesful!");
            Statement s1= conn.createStatement();
            Statement s2= conn.createStatement();
            Statement s3= conn.createStatement();
            Statement s4= conn.createStatement();

            if(resstat == 1)
            {

                String sqlproj = "INSERT INTO tblproject (name,code,location,type,lastdate) " +
                        "VALUES ('" + pprb1.getBeanprojname() + "' , "
                        + "'" + pprb1.getBeanprojcode() +"' ,"
                        + "'" + pprb1.getBeanprojlocation() +"' ,"
                        + "'" + pprb1.getBeanprojtype() +"' ,"
                        + "'" + pprb1.getBeanprojlastdate() +"')";

                String sqlreq1="INSERT INTO tblrequirements (code,designation,skillset,exp,ncand)" +
                        "VALUES ('" + pprb1.getBeanprojcode() + "' , "
                        + "'" + pprb2.getBeandesg() +"' ,"
                        + "'" + pprb2.getBeanskill() +"' ,"
                        + "'" + pprb2.getBeanexp() +"' ,"
                        + "'" + pprb2.getBeanncand() +"')";

                String sqlreq2="INSERT INTO tblrequirements (code,designation,skillset,exp,ncand)" +
                        "VALUES ('" + pprb1.getBeanprojcode() + "' , "
                        + "'" + pprb3.getBeandesg() +"' ,"
                        + "'" + pprb3.getBeanskill() +"' ,"
                        + "'" + pprb3.getBeanexp() +"' ,"
                        + "'" + pprb3.getBeanncand() +"')";

                String sqlreq3="INSERT INTO tblrequirements (code,designation,skillset,exp,ncand)" +
                        "VALUES ('" + pprb1.getBeanprojcode() + "' , "
                        + "'" + pprb4.getBeandesg() +"' ,"
                        + "'" + pprb4.getBeanskill() +"' ,"
                        + "'" + pprb4.getBeanexp() +"' ,"
                        + "'" + pprb4.getBeanncand() +"')";


                s1.executeUpdate(sqlproj);
                System.out.println("Proj updation successful!");
                s2.executeUpdate(sqlreq1);
                System.out.println("Req1 updation successful!");
                s3.executeUpdate(sqlreq2);
                System.out.println("Req2 updation successful!");
                s4.executeUpdate(sqlreq3);
                System.out.println("Req3 updation successful!");
            }

        } catch (Exception e){

            out.println("Failed!"+ e);
            resstat=0;
        }

        if(resstat==1)
            return true;
        else
            return false;
    }

}

只有前 2 个查询被执行（即控制台 o/p 是：项目更新成功！ Req1 更新成功！");

这是我的两个表结构

Table tblproject:

Field        Type           Null     Key
-----------------------------------------
name        varchar(100)    YES         
code        varchar(100)    NO       PRI        
location    varchar(100)    YES         
type        varchar(100)    YES         
lastdate    varchar(11)     YES     

Table tblrequirements:

Field        Type           Null     Key
-----------------------------------------
code         varchar(100)    NO         
designation  varchar(100)   YES         
skillset     varchar(100)   YES         
exp          int(11)         NO         
ncand        int(11)         NO         
slno         varchar(45)     NO       PRI

我哪里错了？

【问题讨论】：

您收到错误消息了吗？
没有任何错误，甚至在堆栈跟踪中也没有异常！
尝试在语句执行之间使用提交。您可能遇到了阻塞。
在每个语句执行之间尝试使用 conn.comit()。还是没有运气！
最后两个查询确实看起来与第二个查询相同，你怎么能说它们不起作用？

标签： java mysql datasource executequery

【解决方案1】：

请尝试批量执行多个插入语句。下面给出的例子

        PreparedStatement pstmt = conn.prepareStatement("INSERT INTO ....  VALUES(?,?)");

        pstmt.setString(1, "some value 1");
        pstmt.setString(2, "other value 1");
        pstmt.addBatch();

        pstmt.setString(1, "some value 2");
        pstmt.setString(2, "other value 2");
        pstmt.addBatch();

        pstmt.setString(1, "some value 3");
        pstmt.setString(2, "other value 3");
        pstmt.addBatch();

        pstmt.executeBatch();

在您的代码中，SQL 语句将无缘无故地被多次评估。也不是真正可读和简单。

【讨论】：