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You can use ensureIndex() to boost the performance of count() method in MongoDB. To understand the concept, let us create a collection with the document. The query to create a collection with a document is as follows −> db.countPerformanceDemo.insertOne({"StudentName":"John", "StudentCountryName":"US"}); { "acknowledged" : true, "insertedId" : ObjectId("5c8ebcf82f684a30fbdfd55f") } > db.countPerformanceDemo.insertOne({"StudentName":"Mike", "StudentCountryName":"UK"}); { "acknowledged" : true, "insertedId" : ObjectId("5c8ebd042f684a30fbdfd560") } > db.countPerformanceDemo.insertOne({"StudentName":"David", "StudentCountryName":"AUS"}); { "acknowledged" : true, "insertedId" : ObjectId("5c8ebd112f684a30fbdfd561") } > db.countPerformanceDemo.insertOne({"StudentName":"Carol", "StudentCountryName":"US"}); { "acknowledged" : true, "insertedId" : ObjectId("5c8ebd1a2f684a30fbdfd562") } > db.countPerformanceDemo.insertOne({"StudentName":"Bob", "StudentCountryName":"UK"}); { "acknowledged" : true, "insertedId" : ... Read More
You can remove a particular record from a table in a database using the DELETE query.SyntaxDELETE FROM table_name WHERE [condition];To delete a record from a table using JDBC API you need to:Register the driver: Register the driver class using the registerDriver() method of the DriverManager class. Pass the driver class name to it, as parameter.Establish a connection: Connect ot the database using the getConnection() method of the DriverManager class. Passing URL (String), username (String), password (String) as parameters to it.Create Statement: Create a Statement object using the createStatement() method of the Connection interface.Execute the Query: Execute the query using the executeUpdate() method of ... Read More
This example demonstrate about how to make custom dialog 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 button. When user click on button, it will show custom dialog.Step 3 − Add the following code to src/MainActivity.javapackage com.example.andy.myapplication; import android.os.Build; import android.os.Bundle; import android.support.annotation.RequiresApi; import android.support.v7.app.AlertDialog; import android.support.v7.app.AppCompatActivity; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; public class MainActivity extends AppCompatActivity { @RequiresApi(api = ... Read More
This error occurs if let’s say you used var_char instead of varchar type. To remove this type of error, use, for example, varchar(100) instead of var_char(100).Let us now see how this error occurs −mysql> create table removeErrorDemo -> ( -> StudentId int, -> StudentName var_char(50) -> );The following is the output displaying the error −ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'var_char(50) )' at line 4Now let us remove the error. Here is the query ... Read More
Create two time instants:Instant time1 = Instant.now(); Instant time2 = Instant.now().plusSeconds(50);Use between() to get the duration between two time instants:long resMilli = Duration.between(time1, time2).toMillis();Exampleimport java.time.Duration; import java.time.Instant; public class Demo { public static void main(String[] args) { Instant time1 = Instant.now(); Instant time2 = Instant.now().plusSeconds(50); long resMilli = Duration.between(time1, time2).toMillis(); System.out.println("Duration between two time intervals = "+resMilli); } }OutputDuration between two time intervals = 50000
You can use IF in stored procedure and IF() in select statement as well.IF() in select statementIF() in select statement mysql> select if(0=0, 'Hello MySQL', 'condition is wrong');This will produce the following output −+------------------------------------------------------+ | if('test'='test', 'Hello MySQL', 'condition is wrong') | +------------------------------------------------------+ | Hello MySQL | +------------------------------------------------------+ 1 row in set (0.00 sec)The second case if your condition ... Read More
There is no DATEPART() function in MySQL, you need to use MONTH() function to extract the month name from date column. The syntax is as follows:SELECT *FROM yourTableName WHERE MONTH(yourDateColumnName)=yourValue;To understand the above syntax, let us create a table. The query to create a table is as follows:mysql> create table SelectRowFromDatePart -> ( -> Id int NOT NULL AUTO_INCREMENT, -> LoginDate date, -> PRIMARY KEY(Id) -> ); Query OK, 0 rows affected (2.42 sec)Now you can insert some records in the table using ... Read More
The 74138 receives the addresses ranging from A15 to A14 from 8085 Processor by means of the octal line driver 74LS244 which delays 12-nS. Simultaneously IO/M* signal is received from 8085 Processor via 74LS244. After that the CS* signal gets receive by the 27128 from 74LS138 which is 3 to 8 decoder, with a delay of 22 Nano seconds. Hence 27128 receives the CS* signal at the end of 34 nS. Hence the data only comes out from the pins ranging from D7 to D0 of 27128 by 34 nS + tCE = 34 nS + 200 nS = 234 nS. Delays involved in accessing 27128 EPROM in ALS kit.Bus timing characteristics of MR machine cycle
Before getting into example, we should know what sqlite data base in android is. SQLite is an open source SQL database that stores data to a text file on a device. Android comes in with built in SQLite database implementation. SQLite supports all the relational database features. In order to access this database, you don't need to establish any kind of connections for it like JDBC, ODBC etc.This example demonstrate about How to use quote () in Android sqliteStep 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to ... Read More
To get the records of the last days from the current date, you need to use DATE_SUB(). We will also use NOW() to get the current date. The syntax for the same is as followsSELECT *FROM yourTableName WHERE yourDateTimeColumnName BETWEEN DATE_SUB(DATE(NOW()), INTERVAL 2 DAY) AND DATE_SUB(DATE(NOW()), INTERVAL 1 DAY);Let us see an examplemysql> create table get2daysAgoDemo - > ( - > Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, - > Name varchar(20), - > PostDateTime datetime - > ); Query OK, 0 rows affected (1.70 ... Read More