AJAX is not a technology but it is a group of technologies (as Javascript, CSS, XHTML, DOM etc). We can also say it is a combination of client side technologies that provides asynchronous communication b\w user interface and web server so that partial page rendering occurs instead of complete page post back. It is platform independent means AJAX is a cross platform technology.
Web services are components on a Web server that a client application can call by making HTTP requests across the Web. ASP.NET enables you to create custom Web services or to use built-in application services, and to call these services from any client application.
According to Microsoft, "ASP.NET is a technology for building powerful, dynamic Web applications and is part of the .NET Framework". Infact Asp.Net is a programming framework used to develop web applications and web services. Basically it is next version of asp. It provides the easy way to build, deploy & run web application on any browser.
JQuery is a cross-browser JavaScript library designed to simplify the client-side scripting of HTML.It was released in january 2006 at BarCamp NYC by John Resig. jQuery is free, open source scripting language. JQuery's syntax is designed to make it easier to navigate a document, select DOM elements, create animations, handle events, and develop Ajax applications.
SQL commands are a set of instructions that are used to interact with the database like Sql Server, MySql, Oracle etc. SQL commands are responsible to create and to do all the manipulation on the database. These are also responsible to give/take out access rights on a particular database.
A key is a single or combination of multiple fields in a table. Its is used to fetch or retrieve records/data-rows from data table according to the condition/requirement. Keys are also used to create relationship among different database tables.
Constraints are some rules that enforce on the data to be enter into the database table. Basically constraints are used to restrict the type of data that can insert into a database table.Constraints can be defined in two ways:
OOP is a design philosophy. It stands for Object Oriented Programming. Object-Oriented Programming (OOP) uses a different set of programming languages than old procedural programming languages (C, Pascal, etc.). Everything in OOP is grouped as self sustainable "objects". Hence, you gain re-usability by means of four main object-oriented programming concepts.
Sql joins are used to fetch/retrieve data from two or more data tables, based on a join condition. A join condition is a relationship among some columns in the data tables that take part in Sql join. Basically data tables are related to each other with keys. We use these keys relationship in sql joins.
LINQ stands for Language-Integrated Query. Basically LINQ address the current database development model in the context of Object Oriented Programming Model. If some one wants to develop database application on .Net platform the very simple approach he uses ADO.Net. ADO.Net is serving as middle ware in application and provides complete object oriented wrapper around the database SQL.