Let us first create a collection with documents −> db.arrayElementsNotGreaterThanDemo.insertOne({"Scores":[89, 43, 32, 45]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd9e9f9b50a6c6dd317adb3") } > db.arrayElementsNotGreaterThanDemo.insertOne({"Scores":[32, 33, 34, 40]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd9ea13b50a6c6dd317adb4") } > db.arrayElementsNotGreaterThanDemo.insertOne({"Scores":[45, 56, 66, 69]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd9ea25b50a6c6dd317adb5") } > db.arrayElementsNotGreaterThanDemo.insertOne({"Scores":[46, 66, 77, 88]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd9ea3cb50a6c6dd317adb6") }Following is the query to display all documents from a collection with the help of find() method −> db.arrayElementsNotGreaterThanDemo.find().pretty();This will produce the following output −{    "_id" : ObjectId("5cd9e9f9b50a6c6dd317adb3"),    "Scores" : [ ... Read More

To view the indexes, you can use SHOW command.Following is the syntax −show index from yourTableName;Let us first create a table −mysql> create table DemoTable    (    Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,    FirstName varchar(20),    LastName varchar(20)    ); Query OK, 0 rows affected (0.46 sec)Following is the query to create an index −mysql> create index id_FirstName on DemoTable(Id, FirstName); Query OK, 0 rows affected (0.52 sec) Records : 0 Duplicates : 0 Warnings : 0Following is the query to view the indexes I have set up in MySQL −mysql> show index from DemoTable;This will produce ... Read More

To work with multiple AND conditions in MySQL, following is the syntax −select *from yourTableName where yourColumnName1=yourValue1 and yourColumnName2=yourValue2 and yourColumnName3=yourValue3;Let us first create a table −mysql> create table DemoTable    (    StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY,    StudentName varchar(20),    StudentAge int,    StudentCountryName varchar(40)    ); Query OK, 0 rows affected (0.59 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(StudentName, StudentAge, StudentCountryName) values('John', 23, 'US'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable(StudentName, StudentAge, StudentCountryName) values('Carol', 21, 'UK'); Query OK, 1 row affected (0.15 sec) mysql> insert ... Read More

To check if table exists, use the following syntax −CREATE TABLE IF NOT EXISTS yourTableName (    yourColumnName1 dataType,    .    .    .    .    N );Here, we will try to create a table that already exists and then it will produce a warning message “Table already exists”. Let us first create a table. This table already exists −mysql> CREATE TABLE IF NOT EXISTS DemoTable    (    Id int    ); Query OK, 0 rows affected, 1 warning (0.06 sec)The warning message is as follows −mysql> show warnings;Output+-------+------+-------------------------------------+ | Level | Code | Message ... Read More

For this, use the $hour operator. Let us first create a collection with documents with one of the field as date −> db.mongoDbSearchForHoursDemo.insertOne({"CustomerName":"Larry", "OrderDatetime":new ISODate("2019-01-31 09:45:50")}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd6e8a86d78f205348bc62a") } > db.mongoDbSearchForHoursDemo.insertOne({"CustomerName":"Larry", "OrderDatetime":new ISODate("2019-02-21 01:10:01")}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd6e8b86d78f205348bc62b") } > db.mongoDbSearchForHoursDemo.insertOne({"CustomerName":"Larry", "OrderDatetime":new ISODate("2019-04-01 04:10:11")}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd6e8e26d78f205348bc62c") } > db.mongoDbSearchForHoursDemo.insertOne({"CustomerName":"Larry", "OrderDatetime":new ISODate("2019-05-11 08:53:01")}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd6e8f26d78f205348bc62d") }Following is the query to display all documents from a collection with the help of find() method −> db.mongoDbSearchForHoursDemo.find().pretty();This will ... Read More

Let us first create a table −create table DemoTable (    Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,    ShippingDate timestamp );Insert some records in the table using insert command. Here, we have included the current date with NOW() −INSERT INTO DemoTable(ShippingDate) VALUES(now());Display all records from the table using select statement −SELECT *FROM DemoTable;OutputFollowing is the screenshot of query in MySQL workbench to set NOW() to timestamp field “ShippingDate”. The query also displays the output below −

Yes, it is possible with triggers. You can create trigger for automatic conversion on lower case. Let us first create a table −mysql> create table DemoTable    (    StudentSubject text    ); Query OK, 0 rows affected (0.61 sec)Let us create a trigger for automatic conversion on lower case −mysql> CREATE TRIGGER lowerCaseOnInsertDemo BEFORE INSERT ON DemoTable FOR EACH ROW    SET NEW.StudentSubject = LOWER(NEW.StudentSubject); Query OK, 0 rows affected (0.21 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('MOngoDb'); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable values('JaVA'); Query OK, ... Read More

Use the concept of initializeUnorderedBulkOp(). Let us first create a collection with documents −>db.upDateMultipleRowsDemo.insertOne({"CustomerName":"John", "CustomerPurchaseAmount":500}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd6ceb06d78f205348bc626") } >db.upDateMultipleRowsDemo.insertOne({"CustomerName":"Chris", "CustomerPurchaseAmount":700}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd6ceb26d78f205348bc627") } >db.upDateMultipleRowsDemo.insertOne({"CustomerName":"David", "CustomerPurchaseAmount":50}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd6ceb36d78f205348bc628") } >db.upDateMultipleRowsDemo.insertOne({"CustomerName":"Larry", "CustomerPurchaseAmount":1900}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd6ceb46d78f205348bc629") }Following is the query to display all documents from a collection with the help of find() method −> db.upDateMultipleRowsDemo.find().pretty();This will produce the following output −{    "_id" : ObjectId("5cd6ceb06d78f205348bc626"),    "CustomerName" : "John",    "CustomerPurchaseAmount" : 500 } {   ... Read More

Use LIKE for this, as shown below −select *from yourTableName where yourColumnName LIKE 'A%';Let us first create a table −mysql> create table DemoTable    (    StudentName varchar(100)    ); Query OK, 0 rows affected (0.66 sec)Now you can insert some records in the table using insert command −mysql> insert into DemoTable values('John Smith'); Query OK, 1 row affected (0.21 sec) mysql> insert into DemoTable values('Adam Smith'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values('Aaron Taylor'); Query OK, 1 row affected (0.43 sec) mysql> insert into DemoTable values('Chris Brown'); Query OK, 1 row affected (0.27 sec)Display ... Read More

Evaluate one or more expressions using the $or operator in MongoDB. Following is the syntax −db.yourCollectionName.find({ $or: [{ "yourFieldName": yourValue1 }, { "yourFieldName": yourValue2} ] } ).pretty();Let us first create a collection with documents −> db.orOperatorDemo.insertOne({"StudentNames":["John", "Carol", "Sam"]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd6b80a6d78f205348bc61b") } > db.orOperatorDemo.insertOne({"StudentNames":["Robert", "Chris", "David"]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd6b8266d78f205348bc61c") } > db.orOperatorDemo.insertOne({"StudentNames":["John"]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd6b8346d78f205348bc61d") }Following is the query to display all documents from a collection with the help of find() method −> db.orOperatorDemo.find().pretty();This will produce the following output −{    "_id" ... Read More