SQL Questions

PL/SQL tables are scalar arrays that can be referenced by a binary digit. They can be used to store values for later queries and calculations.

Catalog views return information that is used by the SQL Server Database Engine. Catalog Views are the most general interface to the catalog metadata and provide the most efficient way to obtain, transform, and present customized forms of this information. All user- available catalog metadata is exposed through catalog views.

Language Integrated Query (LINQ) adds the ability to query objects using .NET languages. The LINQ to SQL object/relational mapping (O/RM) framework provides the following basic features:

- Tools to create classes (usually called entities) mapped to database tables

- Compatibility with LINQ's standard query operations

- The DataContext class, with features such as entity record monitoring, automatic SQL statement generation, record concurrency detection, and much more

User defined data-types in SQL is an extension to the base SQL server data-types by provision of a descriptive name.

We use them to format the database and segregate specific repetitions of rows and columns in the database.

The knowledge of Joins is a MUST for every interviewee. Most SQL programmers have used inner join and  outer join[left/right]; but the catch point here is to also mention cross join and self-join.

Trigger allows us to execute a batch of SQL code when an insert, update or delete command is executed against a specific table.

Triggers are special types of stored procedures that are defined to execute automatically in place of or after data modifications. They can be executed automatically on the insert, delete and update operation.

SELECT DISTINCT(salary) FROM emp as e1 

WHERE (3) = (SELECT COUNT(DISTINCT(salary)) FROM emp as e2  WHERE e1.salary <= e2.salary)