1. What is SQL?
Ans: SQL stands for Structured Query Language. It is a query language used to communicate with a database
2. What is a database query?
Ans: The process of requesting data from the database and receiving back the results is called a database query.
3.What are the SQL statements?
Ans::Data definition language (create, alter, drop, truncate)
Data manipulation language (insert, delete, update)
Data control language (grant, revoke)
Data querying/ retrieving language (select)
Transaction control language (commit, rollback)
4. What is a key?
Ans:: Key is a pre defined constraint. There are different keys are available. Those are
1.Primary key
2.Not null
3.Primary key
4.Check
5.Default
5. What is Primary Key?
Ans: Primary keys are unique identifier for each row.
6. What is Candidate Key?
Ans:: Candidate key is a combination of attributes that can uniquely identify a database record with out any extronious data.
7. What is Foreign key?
Ans:: A foreign key is a referential constraint between two tables. That means foreign key identifies a column or set of column in one table that refers to a column or set of column in another table.
8. What is Unique Key?
Ans:: unique key is a candidate key to uniquely identifies each row in a table. No two distinct rows in a table can have same value in those columns which is declared as unique.
9. What is Composite Key?
Ans:: A key formed by combining at least two or more columns is called composite key
10. What is the difference between Primary Key and unique Key?
Ans:: 1. Both primary key and unique key enforces uniqueness of the columns on which they are defined.
2.By default Primary key creates a clustered index on the column.
By default Unique key creates non clustered index.
3.The major difference is- the primary key does not allow NULL. But Unique key allows one NULL only.
Ans: SQL stands for Structured Query Language. It is a query language used to communicate with a database
2. What is a database query?
Ans: The process of requesting data from the database and receiving back the results is called a database query.
3.What are the SQL statements?
Ans::Data definition language (create, alter, drop, truncate)
Data manipulation language (insert, delete, update)
Data control language (grant, revoke)
Data querying/ retrieving language (select)
Transaction control language (commit, rollback)
4. What is a key?
Ans:: Key is a pre defined constraint. There are different keys are available. Those are
1.Primary key
2.Not null
3.Primary key
4.Check
5.Default
5. What is Primary Key?
Ans: Primary keys are unique identifier for each row.
6. What is Candidate Key?
Ans:: Candidate key is a combination of attributes that can uniquely identify a database record with out any extronious data.
7. What is Foreign key?
Ans:: A foreign key is a referential constraint between two tables. That means foreign key identifies a column or set of column in one table that refers to a column or set of column in another table.
8. What is Unique Key?
Ans:: unique key is a candidate key to uniquely identifies each row in a table. No two distinct rows in a table can have same value in those columns which is declared as unique.
9. What is Composite Key?
Ans:: A key formed by combining at least two or more columns is called composite key
10. What is the difference between Primary Key and unique Key?
Ans:: 1. Both primary key and unique key enforces uniqueness of the columns on which they are defined.
2.By default Primary key creates a clustered index on the column.
By default Unique key creates non clustered index.
3.The major difference is- the primary key does not allow NULL. But Unique key allows one NULL only.
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