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Articles by Nishtha Thakur
Page 27 of 40
Count number of elements in an array with MongoDB?
To count number of elements in an array, use the aggregate framework. Let us first create a collection with documents −>db.countNumberOfElementsDemo.insertOne({"UserMessage":["Hi", "Hello", "Bye", "Awesome"]}); { "acknowledged" : true, "insertedId" : ObjectId("5cef8ec2ef71edecf6a1f6a1") }Display all documents from a collection with the help of find() method −> db.countNumberOfElementsDemo.find().pretty();This will produce the following output −{ "_id" : ObjectId("5cef8ec2ef71edecf6a1f6a1"), "UserMessage" : [ "Hi", "Hello", "Bye", "Awesome" ] }Following is the query to count number of elements in an array −> db.countNumberOfElementsDemo.aggregate({$project: { NumberOfElements: { $size:"$UserMessage" }}})This will produce ...
Read MoreApostrophe replacement in MySQL query?
To replace apostrophe, you can use replace(). Following is the syntax −update yourTableName set yourColumnName=replace(yourColumnName, '\'', '');Let us first create a table −mysql> create table DemoTable ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, Sentence varchar(100) ); Query OK, 0 rows affected (0.17 sec)Insert some records in the table using insert command. Apostrophe is added for the sentence −mysql> insert into DemoTable(Sentence) values('Chris\'s Father'); Query OK, 1 row affected (0.07 sec) mysql> insert into DemoTable(Sentence) values('Larry\'s Mother'); Query OK, 1 row affected (0.06 sec)Display all records from the table using select statement −mysql> select *from ...
Read MoreJava DatabaseMetaData getMaxColumnsInOrderBy() method with example.
The getMaxColumnsInOrderBy() method of the DatabaseMetaData interface is used to find out the maximum number of columns that the underlying database allows in an ORDER BY clause.This method returns an integer value, representing the maximum number of columns allowed in an ORDER BY clause. If this value is 0 it indicates that there is no limit or, limit is unknown.To get the DatabaseMetaData object −Make sure your database is up and running.Register the driver using the registerDriver() method of the DriverManager class. Pass an object of the driver class corresponding to the underlying database.Get the connection object using the getConnection() ...
Read MorePull row with lowest number in a MySQL column?
Use aggregate function MIN() along with GROUP BY for this. Here, we will display the minimum ID for NumberOfProduct . Let us first create a table −mysql> create table DemoTable ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, NumberOfProduct int ); Query OK, 0 rows affected (0.19 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(NumberOfProduct) values(40); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable(NumberOfProduct) values(40); Query OK, 1 row affected (0.08 sec) mysql> insert into DemoTable(NumberOfProduct) values(60); Query OK, 1 row affected (0.07 sec) mysql> ...
Read MoreJava DatabaseMetaData getMaxConnections() method with example.
The getMaxConnections() method of the DatabaseMetaData interface is used to find out the maximum number of connections that the underlying database allows at a time.This method returns an integer value, representing the maximum number of connections allowed at a time. If this value is 0 it indicates that there is no limit or, limit is unknown.To get the DatabaseMetaData object −Make sure your database is up and running.Register the driver using the registerDriver() method of the DriverManager class. Pass an object of the driver class corresponding to the underlying database.Get the connection object using the getConnection() method of the DriverManager class. ...
Read MoreMySQL Stored Procedure to create a table?
Following is the query to create a stored procedure that creates a table. Here, we are creating a table with three columns, one of them is Id −mysql> DELIMITER // mysql> CREATE PROCEDURE Stored_Procedure_CreatingTable() BEGIN create table DemoTable ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, UserFirstName varchar(20), UserLastName varchar(20) ); END; // Query OK, 0 rows affected (0.16 sec) mysql> DELIMITER ;Now you can call stored procedure with the help of CALL command −mysql> call Stored_Procedure_CreatingTable(); ...
Read MoreJava DatabaseMetaData getMaxStatementLength() method with example.
The getMaxStatementLength() method of the DatabaseMetaData interface is used to find out the maximum number of characters that the underlying database allows in a single SQL statement.This method returns an integer value, representing the maximum number of characters allowed in an SQL statement. If this value is 0 it indicates that there is no limit or, limit is unknown.To get the DatabaseMetaData object −Make sure your database is up and running.Register the driver using the registerDriver() method of the DriverManager class. Pass an object of the driver class corresponding to the underlying database.Get the connection object using the getConnection() method ...
Read MoreMySQL Select when a grouped record has multiple matching strings?
You can use regular expression for this. Let us first create a table −mysql> create table DemoTable ( ProductId int NOT NULL AUTO_INCREMENT PRIMARY KEY, ProductName varchar(20) ); Query OK, 0 rows affected (0.19 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(ProductName) values('Product-1'); Query OK, 1 row affected (0.05 sec) mysql> insert into DemoTable(ProductName) values('Product2'); Query OK, 1 row affected (0.06 sec) mysql> insert into DemoTable(ProductName) values('Product1'); Query OK, 1 row affected (0.04 sec) mysql> insert into DemoTable(ProductName) values('Product-3'); Query OK, 1 row affected (0.05 sec) mysql> ...
Read MoreFetch data between two rows in MySQL?
To fetch data between two rows, use the concept of LIMIT. Let us first create a table −mysql> create table DemoTable ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, Name varchar(10) ); Query OK, 0 rows affected (0.22 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(Name) values('Larry'); Query OK, 1 row affected (0.06 sec) mysql> insert into DemoTable(Name) values('Robert'); Query OK, 1 row affected (0.05 sec) mysql> insert into DemoTable(Name) values('Chris'); Query OK, 1 row affected (0.05 sec) mysql> insert into DemoTable(Name) values('David'); Query OK, 1 row affected ...
Read MoreHow can we sort a query using ORDER BY CASE WHEN REGEXP?
Use regular expression along with CASE statement. Let us first create a table −mysql> create table DemoTable ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, Value varchar(20) ); Query OK, 0 rows affected (0.66 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(Value) values('101'); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable(Value) values('P'); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable(Value) values('A'); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable(Value) values('53'); Query OK, 1 row affected (0.13 sec) mysql> ...
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