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Articles by Anvi Jain
Page 25 of 43
Creating an index on a nested MongoDB field?
You can use dot(.) notation for this. Let us first create a collection with documents −> db.createIndexOnNestedFieldDemo.insertOne( {"UserDetails":{"UserPersonalDetails":{"UserFirstName":"John", "UserLastName":"Smith"}}}); { "acknowledged" : true, "insertedId" : ObjectId("5ce929c778f00858fb12e916") } > > db.createIndexOnNestedFieldDemo.insertOne( {"UserDetails":{"UserPersonalDetails":{"UserFirstName":"Chris", "UserLastName":"Brown"}}}); { "acknowledged" : true, "insertedId" : ObjectId("5ce929d678f00858fb12e917") } > db.createIndexOnNestedFieldDemo.insertOne( {"UserDetails":{"UserPersonalDetails":{"UserFirstName":"David", "UserLastName":"Miller"}}}); { "acknowledged" : true, "insertedId" : ObjectId("5ce929e378f00858fb12e918") }Following is the query to display all documents from a collection with the help of find() method −> db.createIndexOnNestedFieldDemo.find().pretty();This will produce the following output −{ "_id" : ObjectId("5ce929c778f00858fb12e916"), "UserDetails" : { ...
Read MoreMySQL query to select a row which contains same number in a column with set of numbers separated by comma?
You need to use FIND_IN_SET() for this. Let us first create a table −mysql> create table DemoTable ( CustomerId int NOT NULL AUTO_INCREMENT PRIMARY KEY, CustomerName varchar(20), CustomerAllProductPrice text ); Query OK, 0 rows affected (0.30 sec)Insert some records in the table using insert command. Here, we are inserting numbers separated by comma −mysql> insert into DemoTable(CustomerName, CustomerAllProductPrice) values('Chris', '245, 345, 678, 90, 45, 56, 78'); Query OK, 1 row affected (0.03 sec) mysql> insert into DemoTable(CustomerName, CustomerAllProductPrice) values('Chris', '98, 99, 90, 56, 77'); ...
Read MoreMongoDB. max length of field name?
MongoDB supports the BSON format data, so there is no max length of field name. Let us first create a collection with documents −>db.maxLengthDemo.insertOne({"maxLengthhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh":"This is demo"}); { "acknowledged" : true, "insertedId" : ObjectId("5ce97ac978f00858fb12e926") }Following is the query to display all documents from a collection with the help of find() method −> db.maxLengthDemo.find();This will produce the following output.{ "_id" : ObjectId("5ce97ac978f00858fb12e926"), "maxLengthhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh" : "This is demo" }
Read MoreHow to fetch only N rows at a time in MySQL?
To fetch only N rows at a time, you can use LIMIT operator. Following is the syntax −select *from yourTableNameLIMIT 0, N;Let us first create a table −mysql> create table DemoTable ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, Name varchar(20) ); Query OK, 0 rows affected (0.25 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(Name) values('John'); Query OK, 1 row affected (0.08 sec) mysql> insert into DemoTable(Name) values('Larry'); Query OK, 1 row affected (0.07 sec) mysql> insert into DemoTable(Name) values('Bob'); ...
Read MoreSelect random number from a specific list in MySQL?
You can use elt() along with rand() for this. Let us select random number from a specific list.mysql> SELECT ELT(FLOOR(RAND() * 10) + 1, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000) AS random_value_from_listOfValues;This will produce the following output −+--------------------------------+ | random_value_from_listOfValues | +--------------------------------+ | 1000 | +--------------------------------+ 1 row in set (0.00 sec)Now we will run the query again to select random number from a specific list.mysql> SELECT ELT(FLOOR(RAND() * ...
Read MoreQuery array of nested string with MongoDB?
To query array of nested string, you can use the dot(.) notation. Let us first create a collection with documents −> db.nestedStringDemo.insertOne( { "CustomerName": "John", "CustomerOtherDetails": [ { "Age":29, "CountryName": "US" }, { "CompanyName": "Amazon", "Salary": 150000, "ProjectName": ["Online Library Management System", "Pig Dice Game"] } ] } ); { "acknowledged" : true, "insertedId" : ObjectId("5cea4629ef71edecf6a1f690") } > db.nestedStringDemo.insertOne( { "CustomerName": "Chris", "CustomerOtherDetails": [ { "Age":27, "CountryName": "AUS" }, { "CompanyName": "Google", "Salary": 250000, "ProjectName": ["Chat Application", "Game ...
Read MoreSelect and add result of multiplying two columns from a table in MySQL?
You can use aggregate function SUM() for this. Let us first create a table −mysql> create table DemoTable ( CustomerId int NOT NULL AUTO_INCREMENT PRIMARY KEY, CustomerProductName varchar(100), CustomerProductQuantity int, CustomerPrice int ); Query OK, 0 rows affected (0.17 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(CustomerProductName, CustomerProductQuantity, CustomerPrice) values('Product-1', 5, 400); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable(CustomerProductName, CustomerProductQuantity, CustomerPrice) values('Product-2', 3, 100); Query OK, 1 row affected (0.06 sec) mysql> insert into DemoTable(CustomerProductName, CustomerProductQuantity, CustomerPrice) values('Product-1', 2, 300); Query OK, 1 ...
Read MoreGet distinct first word from a string with MongoDB?
To get distinct first word from a string, you can use distinct(). Let us first create a collection with documents −> db.distinctFirstWordDemo.insertOne( { "_id": 100, "StudentName":"John", "StudentFeature": "John is a good player", "Subject":"MongoDB" } ); { "acknowledged" : true, "insertedId" : 100 } > db.distinctFirstWordDemo.insertOne( { "_id": 101, "StudentName":"Carol", "StudentFeature": "Carol is not a good player", "Subject":"MongoDB" } ); { "acknowledged" : true, "insertedId" : 101 }Display all documents from a collection ...
Read MoreOrdering string as a number in a database?
To order string as a number, use CAST(). Following is the syntax −select *from yourTableName ORDER BY CAST(yourColumnName AS SIGNED) DESC;Let us first create a table −mysql> create table DemoTable ( Id varchar(100) ); Query OK, 0 rows affected (0.18 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('3'); Query OK, 1 row affected (0.07 sec) mysql> insert into DemoTable values('20'); Query OK, 1 row affected (0.07 sec) mysql> insert into DemoTable values('34'); Query OK, 1 row affected (0.06 sec) mysql> insert into DemoTable values('21'); Query OK, 1 row ...
Read MoreHow to sum based on field value in MySQL?
To sum based on field values, use aggregate function SUM() along with CASE statement. Let us first create a table −mysql> create table DemoTable ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, Price int, isValidCustomer boolean, FinalPrice int ); Query OK, 0 rows affected (0.23 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(Price, isValidCustomer, FinalPrice) values(20, false, 40); Query OK, 1 row affected (0.09 sec) mysql> insert into DemoTable(Price, isValidCustomer, FinalPrice) values(45, true, 10); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable(Price, isValidCustomer, FinalPrice) ...
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