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Articles by Chandu yadav
Page 68 of 81
Check how many rows are in a MySQL database table?
To know how many rows are in a ySQL database table, you need to use aggregate function COUNT(*).The syntax is as followsSELECT COUNT(*) FROM yourTableName;To understand the above syntax, let us create a table. The query to create a table is as followsmysql> create table CountRowsDemo - > ( - > Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, - > Name varchar(20) - > ); Query OK, 0 rows affected (0.78 sec)Insert some records in the table using insert command.The query is as followsmysql> insert into CountRowsDemo(Name) values(NULL); Query OK, 1 row affected (0.15 sec) mysql> ...
Read MoreHow to add a "created at" column in a table to set the timestamp in MySQL?
You need to use ALTER command to add a created at column to an already created table in MySQL.Let us first create a table. The query to create a table is as follows. Here is your table without the “created at” columnmysql> create table formDemo - > ( - > Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, - > Email varchar(128), - > PhoneNumber varchar(15), - > Country varchar(30), - > Platform varchar(40) - > ); Query OK, 0 ...
Read MoreChange a MySQL Column datatype from text to timestamp?
To change a MySQL column datatype from text to timestamp, you need to use ALTER command.The syntax is as followsALTER TABLE yourTableName MODIFY COLUMN yourColumnName TIMESTAMP;To understand the above syntax, let us create a table.The query to create a table is as followsmysql> create table textTotimestampdemo - > ( - > Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, - > Source text - > ); Query OK, 0 rows affected (0.44 sec)Here is the description of table using DESC command.The syntax is as followsDESC yourTableName;The query is as followsmysql> desc textTotimestampdemo;The following is the output+--------+---------+------+-----+---------+----------------+ | ...
Read MoreHow to get default device sdk version in android?
This example demonstrate about How to get default device sdk version 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 to show device sdk version.Step 3 − Add the following code to java/MainActivity.xmlpackage com.example.myapplication; import android.Manifest; import android.content.Context; import android.content.pm.PackageManager; import android.os.Build; import android.os.Bundle; import android.support.annotation.NonNull; import android.support.annotation.RequiresApi; import android.support.v4.app.ActivityCompat; import android.support.v7.app.AppCompatActivity; import android.telephony.TelephonyManager; import android.widget.TextView; import static android.Manifest.permission.READ_PHONE_NUMBERS; import ...
Read MoreCan we exclude entries with "0" while using MySQL AVG function?
To exclude entries with “0”, you need to use NULLIF() with function AVG().The syntax is as followsSELECT AVG(NULLIF(yourColumnName, 0)) AS anyAliasName FROM yourTableName;Let us first create a tablemysql> create table AverageDemo - > ( - > Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, - > StudentName varchar(20), - > StudentMarks int - > ); Query OK, 0 rows affected (0.72 sec)Insert some records in the table using insert command.The query is as followsmysql> insert into AverageDemo(StudentName, StudentMarks) values('Adam', NULL); Query OK, 1 row affected (0.12 sec) mysql> insert into AverageDemo(StudentName, StudentMarks) values('Larry', 23); Query OK, ...
Read MoreGenerate Infinite Stream of Double in Java using DoubleStream.iterate()
The DoubleStream.iterate() returns an infinite sequential ordered DoubleStream produced by iterative application of a function f to an initial element seed, producing a Stream consisting of seed.The syntax is as followsstatic DoubleStream iterate(double seed, DoubleUnaryOperator f)Here, seed is the initial element and f is a function to be applied to the previous element to produce a new element.To use the DoubleStream class in Java, import the following packageimport java.util.stream.DoubleStream;The following is an example to generate infinite stream of Double in Java with DoubleStream.iterate()Exampleimport java.util.stream.DoubleStream; public class Demo { public static void main(String[] args) { ...
Read MoreIs it possible to enforce data checking in MySQL using Regular Expression?
Yes, it is possible to enforce data checking in MySQL using regular expression. First, you need to create a table. After that you need to create a trigger before insert in table. Here, we will be checking the Phone Number format.The query to create a table is as followsmysql> create table enforceDataUsingRegularExpression - > ( - > yourPhoneNumber varchar(60) - > ); Query OK, 0 rows affected (0.59 sec)The query to create a trigger is as followsmysql> DELIMITER // mysql> CREATE TRIGGER enforce_phone_check BEFORE INSERT ON enforceDataUsingRegularExpression - ...
Read MoreGet only the file extension from a column with file names as strings in MySQL?
For this, use the substring_index() function.The syntax is as followsselect substring_index(yourColumnName, '. ', -1) AS anyAliasNamefrom yourTableName;Let us first create a table. The query to create a table is as followsmysql> create table AllFiles - > ( - > Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, - > UserName varchar(10), - > FileName varchar(100) - > ); Query OK, 0 rows affected (0.65 sec)Insert some records in the table using insert command.The query is as followsmysql> insert into AllFiles(UserName, FileName) values('Larry', 'AddTwoNumber.java'); Query OK, 1 ...
Read MoreHow to get default phone Network operator name in android?
This example demonstrate about How to get default phone Network operator name 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 a text view to show the phone network operator name.Step 3 − Add the following code to java/MainActivity.xmlpackage com.example.myapplication; import android.Manifest; import android.content.Context; import android.content.pm.PackageManager; import android.os.Build; import android.os.Bundle; import android.support.annotation.NonNull; import android.support.annotation.RequiresApi; import android.support.v4.app.ActivityCompat; import android.support.v7.app.AppCompatActivity; import android.telephony.TelephonyManager; import android.widget.TextView; ...
Read MoreHow to find the previous and next record using a single query in MySQL?
You can use UNION to get the previous and next record in MySQL.The syntax is as follows(select *from yourTableName WHERE yourIdColumnName > yourValue ORDER BY yourIdColumnName ASC LIMIT 1) UNION (select *from yourTableName WHERE yourIdColumnName < yourValue ORDER BY yourIdColumnName DESC LIMIT 1);To understand the concept, let us create a table. The query to create a table is as followsmysql> create table previousAndNextRecordDemo - > ( - > Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, - > Name varchar(30) - > ); Query OK, 0 rows affected (1.04 ...
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