Question

尝试格式化问题。我有下面提到的一组查询。现在我想要一些功能可以确保所有查询都应该执行或者不执行（如果发生某种错误）我只想维护我的数据库处于适当的状态。

    con.setAutoCommit(false);
                                    String qry = "insert into tblAllotment(Employee_ID,Employee_Name,Area,Building_Name,Flat_Type,Flat_No,Date_Application,Date_Allotment,Admin_Code) values(" + id + ",'" + name[1] + "','" + area + "','" + flat[2] + "','" + flat[1] + "','" + flat[0] + "','" + dte + "','" + date + "'," + uid + ")";
                                    String qry1 = "insert into tblFlat_Report(Flat_No,Area_Code,Employee_ID,Date_Allottment,Admin_Code)values('" + flat[0] + "'," + acode + "," + id + ",'" + date + "'," + uid + ")";
                                    //String qry2="UPDATE tblUser_Report t1 JOIN (SELECT MAX(S_Date) s_date FROM tblUser_Report WHERE Employee_ID = "+id+") t2 ON t1.s_date = t2.s_date SET t1.Status = 'A', t1.S_Date ='"+date+"' WHERE t1.Employee_ID ="+id+"";
                                    String qry2 = "insert into tblUser_Report(Employee_ID,Employee_Name,S_Date,Area,Status) values(" + id + ",'" + name[1] + "','" + date + "','" + area + "','A')";
                                    String qry3 = "update tblFlat set Status ='A' where Flat_No='" + flat[0] + "' AND Area_Code=" + acode + " ";
                                    String qry4 = "update tblUser set WL_Flag='N' where Employee_ID=" + id + "";
                                    st = con.createStatement();
                                    int i = st.executeUpdate(qry);
                                    int j = st.executeUpdate(qry1);
                                    int k = st.executeUpdate(qry2);
                                    int l = st.executeUpdate(qry3);
                                    int m = st.executeUpdate(qry4);
con.commit();

                                    if (i != 0 & j != 0 & k != 0 & l != 0 & m != 0) {
                                        Done = "Data Inserted Successfully...!!!";
                                    } else {
                                        System.out.println("Error Occured");
                                    }
                                } catch (SQLException e) {
con.rollback();
                                    System.out.println(e.getMessage());
                                }
    }

Answer 1

您的数据库必须提供交易。如果您使用MySQL，则不能使用MyISAM ~~数据库~~表，您必须使用InnoDB（例如）。

您在代码开头处开始交易，然后检查每个结果。如果出现错误，则发出回滚。如果一切正常，您最后会发出提交。

你的样子应该是这样的：

con.setAutoCommit(false); // at the beginning, to prevent auto committing at each insert/update/delete
// ... your updates, with error checking
con.commit(); // at the end, only if everything went fine.

如果出现错误，请调用con.rollback（）

Answer 2

在try catch中包装您的查询。在try和commit（）的开头添加setAutoCommit（false），在catch块中添加rollback（）。

try {
    conn.setAutoCommit(false);

    // Execute queries

    conn.commit();
} 
catch (SQLException e) {
    conn.rollback();
}

执行所有查询或无执行应该执行

2 个答案: