example of subquery in sql

Example 1: mssql subqueries

USE AdventureWorks2016;
GO
SELECT Ord.SalesOrderID, Ord.OrderDate,
    (SELECT MAX(OrdDet.UnitPrice)
     FROM Sales.SalesOrderDetail AS OrdDet
     WHERE Ord.SalesOrderID = OrdDet.SalesOrderID) AS MaxUnitPrice
FROM Sales.SalesOrderHeader AS Ord;
GO

Example 2: what is subquery in sql

SUBQUERY IS NESTED QUERY INSIDE A SELECT, 
INSERT OR UPDATE METHODS. OR INSIDE ANOTHER SUBQUERY