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Articles by Nishtha Thakur
Page 26 of 40
Update a single list item of a MongoDB document?
To update a single list item, use positional operator($). Let us first create a collection with documents −> db.updateASingleListDemo.insertOne({ _id:1, "EmployeeName":"Chris", "EmployeeDetails": [ {"EmployeeId":"EMP-101", "EmployeeSalary": 18999 }] }); { "acknowledged" : true, "insertedId" : 1 }Following is the query to display all documents from a collection with the help of find() method −> db.updateASingleListDemo.find().pretty();This will produce the following output −{ "_id" : 1, "EmployeeName" : "Chris", "EmployeeDetails" : [ { "EmployeeId" : "EMP-101", "EmployeeSalary" : 18999 } ] }Following is the query ...
Read MoreFilter by several array elements in MongoDB?
For this, you can use $elemMatch operator. The $elemMatch operator matches documents that contain an array field with at least one element that matches all the specified query criteria. Let us first create a collection with documents −> db.filterBySeveralElementsDemo.insertOne( "_id":100, "StudentDetails": [ { "StudentName": "John", "StudentCountryName": "US", }, { "StudentName": "Carol", "StudentCountryName": "UK" } ] } ); { "acknowledged" : true, "insertedId" : 100 } > db.filterBySeveralElementsDemo.insertOne( { ...
Read MoreHow to store time created in a MySQL table?
You can use DEFAULT CURRENT_TIMESTAMP. Keep in mind that it will work only at the time of insertion. Let us first create a table −mysql> create table DemoTable ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, Arrivaltime TIMESTAMP DEFAULT CURRENT_TIMESTAMP ); Query OK, 0 rows affected (0.31 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(Arrivaltime) values('2018-01-31 10:34:56'); Query OK, 1 row affected (0.06 sec) mysql> insert into DemoTable values(); Query OK, 1 row affected (0.06 sec) mysql> insert into DemoTable(Arrivaltime) values('2019-01-31 11:10:12'); Query OK, 1 row affected (0.04 sec)Display ...
Read MoreReplace an array field value with MongoDB?
You can use positional operator $. Let us first create a collection with documents −> db.replaceAnArrayFieldValueDemo.insertOne({"StudentTechnicalSubjects":["MySQL", "SQL Server", "PL/SQL"]}); { "acknowledged" : true, "insertedId" : ObjectId("5cea41e0ef71edecf6a1f68f") }Following is the query to display all documents from a collection with the help of find() method −> db.replaceAnArrayFieldValueDemo.find().pretty();This will produce the following output −{ "_id" : ObjectId("5cea41e0ef71edecf6a1f68f"), "StudentTechnicalSubjects" : [ "MySQL", "SQL Server", "PL/SQL" ] }Following is the query to replace an array field value. Here, we are updating “SQL Server” with “MongoDB” −> db.replaceAnArrayFieldValueDemo.update( {"StudentTechnicalSubjects":"SQL Server"}, ...
Read MoreMySQL query to search exact word from string?
To search exact word from string, use the below syntax −select *from yourTableName where yourColumnName regexp '(^|[[:space:]])yourWord([[:space:]]|$)';Let us first create a table −mysql> create table DemoTable ( Title text ); Query OK, 0 rows affected (0.23 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('This is the Introduction to Java'); Query OK, 1 row affected (0.05 sec) mysql> insert into DemoTable values('This is the Introduction to MongoDB'); Query OK, 1 row affected (0.07 sec) mysql> insert into DemoTable values('This is the Introduction to MySQL'); Query OK, 1 row affected (0.06 ...
Read MoreHow to dynamically build MongoDB query?
To build query dynamically, you need to write some script. Let us first create a collection with documents −> db.dynamicQueryDemo.insertOne({"Name":"John", "Subject":["MongoDB", "MySQL"]}); { "acknowledged" : true, "insertedId" : ObjectId("5cef5c5def71edecf6a1f69a") } > db.dynamicQueryDemo.insertOne({"Name":"John", "Subject":["C", "C++"]}); { "acknowledged" : true, "insertedId" : ObjectId("5cef5c73ef71edecf6a1f69b") } > db.dynamicQueryDemo.insertOne({"Name":"John", "Subject":["MongoDB", "Java"]}); { "acknowledged" : true, "insertedId" : ObjectId("5cef5c8bef71edecf6a1f69c") }Display all documents from a collection with the help of find() method −> db.dynamicQueryDemo.find().pretty();This will produce the following output −{ "_id" : ObjectId("5cef5c5def71edecf6a1f69a"), "Name" : "John", "Subject" : [ ...
Read MoreJava DatabaseMetaData getMaxCharLiteralLength() method with example.
The getMaxCharLiteralLength() method of the DatabaseMetaData interface is used to find out the maximum number of characters that the underlying database allows for a character literal.This method returns an integer value, representing the maximum length of a character literal. 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 MoreCombine columns before matching it with LIKE in a single query in MySQL?
You can use CONCAT() function for this. Let us first create a table −mysql> create table DemoTable ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, Value1 varchar(10), Value2 varchar(10) ); Query OK, 0 rows affected (0.21 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(Value1, Value2) values('10', '345'); Query OK, 1 row affected (0.07 sec) mysql> insert into DemoTable(Value1, Value2) values('14', '789'); Query OK, 1 row affected (0.06 sec) mysql> insert into DemoTable(Value1, Value2) values('18', '234'); Query OK, 1 row affected (0.13 sec)Display all records from the table using ...
Read MoreHow to query all items in MongoDB?
To query all items, use find(). Let us first create a collection with documents −> db.queryAllItemsDemo.insertOne({"StudentDetails":{"StudentName":"John", "StudentSubject":["MongoDB", "MySQL"], "StudentSubjectPrice":[4000, 6000]}, "OtherDetails":{"UserAge":29, "UserCountryName":"US"}}); { "acknowledged" : true, "insertedId" : ObjectId("5cef74ecef71edecf6a1f69f") }Display all documents from a collection with the help of find() method −> db.queryAllItemsDemo.find().pretty();This will produce the following output −{ "_id" : ObjectId("5cef74ecef71edecf6a1f69f"), "StudentDetails" : { "StudentName" : "John", "StudentSubject" : [ "MongoDB", "MySQL" ], "StudentSubjectPrice" : [ 4000, ...
Read MoreMySQL query to get result by month and year based on condition?
You need to use OR condition along with WHERE clause. Let us first create a table −mysql> create table DemoTable ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, MonthNumber int, YearNumber int ); Query OK, 0 rows affected (0.22 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(MonthNumber, YearNumber) values(11, 2018); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable(MonthNumber, YearNumber) values(3, 2019); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable(MonthNumber, YearNumber) values(12, 2018); Query OK, 1 row affected (0.08 sec) mysql> insert ...
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