MySQL Learn Simpli September 6, 2019 no Comments 1. Difference between Primary key and Unique key? Primary key doesn’t allow null value whereas unique key allows multiple null values Primary key doesn’t allow null value whereas unique key allows one null value. Primary key allows one null value whereas unique key doesn’t allow null value. Primary key allows one null value whereas unique key allows multiple null values. None 2. What does RAID stands for? Redundant Array of Independent Disks Reduce Array of Independent Disks Redundant Automatic Individual Durable Redundancy Accelerator Independent Disks None 3. What is meant by Primary Key in SQL? primary is no of rows in table Primary keys are unique identifiers for each row in a table. Primary keys are unique names of a table. Primary keys are integer ids in a table rows. None 4. How many types of indexes are there in SQL server? Integer and string Unique and non-unique none Clustered and Non clustered None 5. What is meant by indexes? Index speed up the data retrieval Index minimize the data redundancy Index stores large number of integer values None of the above. None 6. Which are valid Transaction levels in SQL Server in the following answers? READ UNCOMMITTED All of the above READ COMMITTED REPEATABLE READ None 7. Which is the correct order of query operators in a SQL query? FROM -> OUTER -> GROUP BY -> WHERE FROM -> OUTER -> WHERE -> ON SELECT -> FROM -> WHERE -> OUTER SELECT -> FROM -> OUTER -> WHERE None 8. One table can have more than one combination of columns that uniquely identify the row in a table each combination is called as? Candidate Key Primary key Foreign Key Composite Key None 9. Which is not a valid data type in SQL server in the following answers? money blob xml nvarchar None 10. What do you meant by normalization? It is a set of rules to improve database performance. It is a set of rules to normalize database transactions. None of the above It is a set of database design rules to minimize redundancy. None Time's up
