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Structured query language is the standard command set used to communicate with the relational database management system.
A Database Management system consists of a collection of interrelated data and set of programs to access that data.
What is the purpose of Database systems?
A Database Management system provides a secure and survivable medium for the storage and retrieval of data.In the real world, the data is shared among several users and is persistent.
State the different between Security and Integrity?
Security is a protection from malicious attempts to steal or modify data. Integrity constraints guard against accidental damage to the database, by ensuribg that authorized changes to the database do not result in a loss of data consistency.
Normalisation is an essential part of database design. A good understanding of the semantic of data helps the designer to built efficient design using the concept of normalization.
Define Primary Key?
The primary key is the columns used to uniquely identify each row of a table. A table can have only one primary key. No primary key value can appear in more than one row in the table.
Define Unique Key?
Unique key is a one or more column that must be unique for each row of the table. It is similar to primary key. Primary key column will not accept a null. Whereas the unique key column will accept a null values.
Compare and contrast TRUNCATE and DELETE for a table?
Both the truncate and delete command have the desired outcome of getting rid of all the rows in a table. The difference between the two is that the truncate command is a DDL operation and just moves the high water mark and produces a now rollback. The delete command, on the other hand, is a DML operation, which will produce a rollback and thus take longer to complete.
What is cursors?
Cursor is a database object used by applications to manipulate data in a set on a row-by-row basis, instead of the typical SQL commands that operate on all the rows in the set at one time.
Define Foreign Key?
A foreign Key is a combination of columns with value is based on the primary key values from another table. A foreign key constraint also known as Referential Integrity Constraint.