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:
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.
Triggers are special type of stored procedure that automatically execute when a DDL or DML statement associated with the trigger is executed. Triggers are used to evaluate data before or after data manipulation using DDL and DML statements, to maintain data integrity, to control server operations and access, to audit a server, and to implement business logic or business rule.
Triggers are special type of stored procedure that automatically execute when a DDL or DML statement associated with the trigger is executed. DML Triggers are used to evaluate data after data manipulation using DML statements. We have two types of DML triggers.
Microsoft SQL Server is a Relational Database Management System(RDBMS) developed by Microsoft. It is designed to run on a central server, so that multiple users can access the same data simultaneously. The users normally access the database through an application.