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A primary key is a field or the combination of fields which uniquely specify a row. The Primary key is a special kind of unique key. Primary key values cannot be NULL. For example, the Social Security Number can be treated as the primary key for any individual. A primary key in SQL is a … Read more

A table is a set of organized data. It has rows and columns. Rows here refers to the tuples which represent the simple data item and columns are the attribute of the data items present in particular row. Columns can categorize as vertical, and Rows are horizontal. A table contains a specified number of the … Read more

Data control language allows you to control access to the database. DCL is the only subset of the database which decides that what part of the database should be accessed by which user at what point of time. It includes two commands GRANT and REVOKE. GRANT: to grant the specific user to perform a particular … Read more

Data manipulation language makes the user able to retrieve and manipulate data. It is used to perform the following operations. Insert data into database through INSERT command. Retrieve data from the database through SELECT command. Update data in the database through UPDATE command. Delete data from the database through DELETE command. In SQL, Data Manipulation … Read more

Data definition language (DDL) is the subset of the database which defines the data structure of the database in the initial stage when the database is about to be created. It consists of the following commands: CREATE, ALTER and DELETE database objects such as schema, tables, view, sequence, etc. In SQL, Data Definition Language (DDL) … Read more