Author Archives: Robins

[Two Methods] Ora-00904: invalid group by error identifier

I believe many students encounter the problem of invalid prompt identifier when using group by. Don’t worry, let’s summarize the common solutions to this problem:

Example: take the information of the youngest employee in each department
my SQL statement is as follows:

select name,min(age),(select deptname from dept d where d.deptid=uif.deptid)deptname from userinfo uif group by name,deptname

When you click execute, the system prompts:

ORA-00904:"deptname":Identifier is invalid

Error reason: the field after group by cannot be an alias (if you want to use an alias, you need to nest it at one level)

Solution 1:

--goup by The department name (alias: deptname ) is directly used in the deptid field of the employee information table
select name,min(age),(select deptname from dept d where d.deptid=uif.deptid)deptname from userinfo uif group by uif.name,uif.deptid

Solution 2:

--Grouping after one level of nesting
select us.name,min(us.age),us.deptname from （select name,age,(select deptname from dept d where d.deptid=uif.deptid)deptname from userinfo uif）us
group by us.name,us.deptname

How about this time?If you have any questions, please leave a message to study together~

[Solved] Login with Ubuntu graphical interface, error sorry, that didn’t work.please try again

Sorry, that didn’t work.please try again

Today, I just finished installing Ubuntu 20.04. After setting the root password, I found that the root login would report such an error:
sorry, that didn’t work.please try again

In fact, there is no problem with the command line login, which indicates that it is not the password, but the desktop environment.

vi /etc/pam.d/gdm-autologin
#Note "auth requied pam_succeed_if.so user != root quiet success"

vi /etc/pam.d/gdm-password
#Note "auth requied pam_succeed_if.so user != root quiet success"

[Solved] Caused by: java.lang.ClassNotFoundException: org.apache.flink.api.common.typeinfo.TypeInformation

Exception in thread “main” java.lang.NoClassDefFoundError: org/apache/flink/api/common/typeinfo/TypeInformation
at io.github.interestinglab.waterdrop.flink.test.RedisSinkTest.main(RedisSinkTest.scala)
Caused by: java.lang.ClassNotFoundException: org.apache.flink.api.common.typeinfo.TypeInformation
Check Provided if there are no errors in the code

SyntaxError: Non-UTF-8 code starting with ‘\xe4‘ in file [How to Solve Chinese encoding problem]

Python 3 uses UTF-8 format by default

Generally, you don’t need to add a word at the beginning– coding:utf-8 —

However, in some Chinese, there will still be unrecognizable cases, and the error of “non-utf-8 code starting with” \ \ xe7 “will be thrown. At this time, you need to add this sentence in the first line.

#-*- coding:utf-8 -*-

MySQL: How to Turn on Functions

I want to customize the function today, but the mysql console reports an error
This function has none of DETERMINISTIC, NO SQL, or READS SQL DATA in its declaration and binary logging is enabled (you might want to use the less safe log_bin_trust_function_creators variable)
It means I don’t have the function function enabled

show variables like '%func%';

Here I have turned on the function function as on

setting parameters to turn on the function function

set global log_bin_trust_function_creators=1;

Ubuntu ODBC MySQL 8 OPTION NOT Work [How to Solve]

Error due to FreeSWITCH using ODBC requirements
If you are using mysql, make sure you are using MYODBC 3.51.18 or higher and enable FLAG_MULTI_STATEMENTS

# vim /etc/odbc.ini
[freeswitch]
Driver = MySQL
SERVER = localhost
PORT = 3306
DATABASE = myDatabase
OPTION = 67108864

Note: option = 67108864   Start SQL batch, freeswitch   ODBC mode must be on

ODBC does not configure SQL preprocessing, resulting in an error when executing multiple SQL statements at the same time

ubuntu20.04

Download and install ODBC driver from MySQL website

Note that the version option of 8x is invalid after setting,

Solution demotion

mysql-connector-odbc-5.3.14-linux-ubuntu19.10-x86-64bit.tar.gz

Verification supports preprocessing methods, which are not described here for ODBC configuration

isql -v freeswitch

delete from sip_ registrations where sub_ host is null and hostname=’VM-0-13-ubuntu’ and network_ ip like ‘%’ and network_ port like ‘%’ and sip_ u

[Solved] panic: proto: duplicate enum registered: raftpb.EntryType

  Error information:

A future release will panic on registration conflicts. See:
https://developers.google.com/protocol-buffers/docs/reference/go/faq#namespace-conflict

panic: proto: duplicate enum registered: raftpb.EntryType

goroutine 1 [running]:
github.com/golang/protobuf/proto.RegisterEnum(0x2461722, 0x10, 0xc0002b29f0, 0xc0002b2a20)
	/user/local/gopath/pkg/mod/github.com/golang/[email protected]/proto/registry.go:104 +0x11f
github.com/coreos/etcd/raft/raftpb.init.0()
	/user/local/gopath/pkg/mod/github.com/coreos/[email protected]+incompatible/raft/raftpb/raft.pb.go:508 +0x52
make: *** [show] error 2

Solution: add to go.mod

replace go.etcd.io/etcd => github.com/coreos/etcd v3.3.10+incompatible

[Solved] KEIL MDK Warning: “no browse info for symbol in this context”

If there is no Chinese path, enter   Option for target-> ouput-> Cancel the check of browse information, click rebuild all target files to recompile all the files, re check the check of browse information, re check the check of browse information, and recompile all the files, the perfect solution, you can go to define happily!!!

Mysql Flashback Warning: C:\Program Files\MySQL\MySQL Server 8.0\bin\mysql.exe

mysql: [ Warning] C:\Program Files\MySQL\MySQL Server 8.0\bin\mysql.exe:   ignoring option  ‘–
Before opening MySQL, it was normal. After entering the password today, it has been flashing back. The warning is as follows:

mysql: [ Warning] C:\Program Files\MySQL\MySQL Server  8.0\bin\mysql.exe:   ignoring   option  ‘– no-beep’   due   to   invalid   value  ‘’.**

terms of settlement:

Open the above path (my computer is like this, the default path, if your path is not the same, it is recommended to find the installation path), find my.ini file, it is recommended to save a copy before changing to prevent modification errors. Open it in Notepad and find the following statement:

Delete the “=” in the red underlined statement and click save.

Reopen the MySQL execution box. Generally speaking, 80% of the problem is solved successfully. However, if you still flash back, right-click to find the folder where MySQL is located and enter the. EXE file from the folder chart. I hope these will help you.

libxx.so: undefined reference, vector.reserve(n) [How to Solve]

background: Trying to avoid reallocation using the STL: std::vector.reserve(n).
declared static std::vector<int> sample_num in class AngleCal, and want to do it in AngleCal::AngleCal() sample_num.reserve(300) (assumming 300 is the size or, alternatively an upper bound on the size)


However, when compiling this AngleCal.cpp into libanglecal.so, the compiler gives the following error.
[build] /usr/bin/ld: ../lib/libanglecal.so: undefined reference to `hitcrt::AngleCal::if_first_detection’
[build] /usr/bin/ld: ../lib/libanglecal.so: undefined reference to `hitcrt::AngleCal::sample_num’
[build] /usr/bin/ld: ../lib/libanglecal.so: undefined reference to `hitcrt::AngleCal::i’
Solution: A static member is shared by all objects of the class. All static data is initialized to zero when the first object is created, if no other initialization is present. We can’t put it in the class definition but it can be initialized outside the class as done in the following example by redeclaring the static variable, using the scope resolution operator :: to identify which class it belongs to.

#include <iostream>
 
using namespace std;

class Box {
   public:
      static int objectCount;
      
      // Constructor definition
      Box(double l = 2.0, double b = 2.0, double h = 2.0) {
         cout <<"Constructor called." << endl;
         length = l;
         breadth = b;
         height = h;
         
         // Increase every time object is created
         objectCount++;
      }
      double Volume() {
         return length * breadth * height;
      }
      
   private:
      double length;     // Length of a box
      double breadth;    // Breadth of a box
      double height;     // Height of a box
};

// Initialize static member of class Box
int Box::objectCount = 0;

int main(void) {
   Box Box1(3.3, 1.2, 1.5);    // Declare box1
   Box Box2(8.5, 6.0, 2.0);    // Declare box2

   // Print total number of objects.
   cout << "Total objects: " << Box::objectCount << endl;

   return 0;
}

The running results are as follows

Constructor called.
Constructor called.
Total objects: 2

Static decorated class members must be initialized outside the class before they can be manipulated.

above.