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Articles by Chandu yadav
Page 77 of 81
Why MySQL NOT NULL shouldn't be added to primary key field?
You do not need to add NOT NULL to primary key field because it gets NOT NULL automatically. Primary key is combination of both NOT NULL and Unique Key.Here is the demo of primary key field. Let us first create a table. The query to create a table is as follows:mysql> create table NotNullAddDemo -> ( -> Id int AUTO_INCREMENT, -> PRIMARY KEY(Id) -> ); Query OK, 0 rows affected (0.81 sec)In the above table, you do not need to add NOT NULL to primary key field because MySQL internally converts it into NOT NULL. To ...
Read MoreHow can I see global locks in MySQL (innodb)?
In order to see the global locks in MySQL (Innodb), use the SHOW command. The below query shows the global locks as well owner of locks and waiters. The following query will also show transaction id and more related to Innodb.The query is as follows:mysql> SHOW ENGINE INNODB STATUS\GThe following is the output:*************************** 1. row *************************** Type: InnoDB Name: Status: ===================================== 2019-01-23 14:46:58 0x2914 INNODB MONITOR OUTPUT ===================================== Per second averages calculated from the last 23 seconds ----------------- BACKGROUND THREAD ----------------- srv_master_thread loops: 87 srv_active, 0 srv_shutdown, 51953 srv_idle srv_master_thread log flush and writes: 0 ---------- SEMAPHORES ---------- OS WAIT ...
Read MoreHow to reload activity in Android?
In some situations, we need to recall activity again from onCreate(). This example demonstrates how to reload activity in Android.Step 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to create a new project.Step 2 − Add the following code to res/layout/activity_main.xml. In the above code, We have taken text view, when a user clicks on text view, it will call Main Activity again.Step 3 − Add the following code to src/MainActivity.javapackage com.example.andy.myapplication; import android.content.Intent; import android.os.Build; import android.os.Bundle; import android.support.annotation.RequiresApi; import android.support.v7.app.AppCompatActivity; import android.view.View; import ...
Read MoreSpecial features of Z-80
In this section we will see some advanced features of Zilog Z-80 Microprocessor. These features are basically compared to the Intel 8085 Microprocessor.The features are listed below −Sr.No.Features & Description1Opcode CountIn this Microprocessor there are 698 Opcodes of different lengths.2Instruction LengthThe instructions can be divided into four categories according to their lengths.There are 202 of 1-byte instructions, 344 of 2-byte instruction74 of 3-byte instruction78 of 4-byte instruction3Opcode LengthThe instructions can also be divided into two parts according to the opcode length. In the instruction set, there are instructions with 1-byte opcode and 2-byte opcode.The number of 1-byte opcode instruction is ...
Read MoreHow to Dynamically Add Views into View in Android?
This example demonstrates How to Dynamically Add Views into View.Step 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to create a new project.Step 2 − Add the following code to res/layout/activity_main.xml. In the above code, we have taken an empty layout. In this layout, we will have dynamic text view.package com.example.andy.myapplication; import android.graphics.Bitmap; import android.graphics.Matrix; import android.os.Build; import android.os.Bundle; import android.os.Handler; import android.support.annotation.RequiresApi; import android.support.v7.app.AppCompatActivity; import android.view.LayoutInflater; import android.view.View; import android.widget.ImageView; import android.widget.LinearLayout; import android.widget.TextView; public class MainActivity extends AppCompatActivity { int view = R.layout.activity_main; ...
Read MorePins of Z-80
The Zilog Z-80 is 40 pin DIP Microprocessor. Here we will see the actual pin level diagram of Z-80 and also the functional pin diagram of it.This is the actual pin diagram of Z-80 Microprocessor. Now we will see the functional pin diagram of it.Now let us see the Pin functions of the Z-80 microprocessor.PinsTypeFunctionA15 – A0Output16-bit address bus, which provides the addresses for memory (up to 64KB)D7 – D0Input/Output8-bit bi-directional data bus to transfer data between memory/IO devices and CPU.BUSACKOutputIt is Bus Acknowledge pin. It indicates the requesting device that the address bus, data bus, control bus enter into ...
Read MoreHow to set global event_scheduler=ON even if MySQL is restarted?
There is a single way by which you can set a global event_scheduler=ON even if MySQL is restarted. You need to set global system variable ON and need to use this system variable even if MySQL restart.For this, I am using system variable @@event_scheduler using select statement. The query is as follows:mysql> select @@event_scheduler;The following is the output:+-------------------+ | @@event_scheduler | +-------------------+ | ON | +-------------------+ 1 row in set (0.00 sec)Now, restart MySQL. The query is as follows:mysql> restart; Query OK, 0 rows affected ...
Read MoreAddition of multi-byte numbers in Z-80
Now, in this section we will see how we can use the Zilog Z-80 Microprocessor to add Multi-byte numbers.In this example, we are using 4-byte numbers (56 2F 7A 89)16 and (21 FB A9 AF)16In the memory, at first, we are storing the byte counts, and then the numbers (from least significant bytes to Most significant bytes) in different segments. So after storing the data, the memory structure will be look like thisAddressValue5000H04H...5050H89H5051H7AH5052H2FH5053H56H...5070HAFH5071HA9H5072HFBH5073H21H...Now, we are writing a program at location 8000H to add these two 4-byte number and store the result at location 5090H onwards.ProgramAddressHex CodesLabelsMnemonicsComments800037SCFSet the carry flag80013FCCFComplement the ...
Read MorePython program to print all the common elements of two lists.
Given two lists, print all the common element of two lists. Examples − Input : L1 = [5, 6, 7, 8, 9] L2 = [5, 13, 34, 22, 90] Output : {5} Explanation The common elements of both the list is 5. Algorithm Step1 : create two user input lists. Step2 : Convert the lists to sets and then print set1&set2. Step3 : set1 and set2 returns the common elements set, where set1 is the list1 and set2 is the list2. Example Code # Python ...
Read MorePython GNU readline Interface
The readline is UNIX specific module. It defines a number of functions to read and write history files in easier way from python interpreter. We can use this module directly or using the rlcompleter module. This module settings may affect the built-in input() method prompt and also the interactive prompt. For the MAC based system (on MAC OS X) this readline module can be implemented using the libedit library. The libedit configuration is different from GNU readline. To use this module, we need to import the readline module in the python code import readline Some methods of ...
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