dcl in sql

Introduction of dcl in sql -: The full name of the dcl is Data Control Language. A data control language (dcl) is a syntax similar to a computer programming language used to control access to data stored in a database. In particular, it is a component of Structured Query Language (SQL).  In other words we can … Read more

internet databases

Internet Databases Introduction-: The expansion of internet and intranet enabled the user to access a large number of data sources available. One of major achievements of this expansion is E commerce which include purchasing of items ranging from a small pens,books,to all other types of consumer goods through internet. Various site are available which provide … Read more

index in sql

Index In sql :- An index is a schema object that can speed up the retrieval of rows by using a pointer. Indexes can be created explicitly or automatically. If we do mot have an index on the column, then a full table scan will occur. An index provides direct and fast access to rows in … Read more

sequence in sql

Sequence in sql-: A sequence is a database object created by a user, and can be shared by multiple users to generate unique integers. We can use the sequence to automatically generate unique integers. A typical usage for sequences is to create a primary key value, which must be unique for each row. The sequence is … Read more

view in sql

Views in sql:-  We can present logical subsets or combination of data by creating views of tables. A view is a logical table based on a table or another view. A view contains no data of its own but is like a window through which data from tables can be viewed or changed. The tables … Read more

constraints in sql

Constraints in sql-: An integrity constraint can be thought of as a way to define a business rule for a column or a table. Integrity constraints are defined with a table and are stored as part of the table’s definition in the data dictionary. This is advantageous as if a rule changes then it has … Read more

joins in sql

SQL Joins -: Display data from multiple tables in sql called the joins. In other words we can say when data from more then one table in database is required a join condition is use there. In one table row is Joined to another table row according to common value existing in corresponding column. as … Read more

operator in sql

Limiting rows using a selection in sql -: We can restrict the row returned the query by using the where clause as like this Select [Distinct]  {* ! column [alias], ….} from table {where condition(S)]; In this syntax : Where – The where clause can compare value in column literal value arithmetic expression or function. It … Read more