BQE Software Database Developer Interview Questions, Process, and Tips

A recursive CTE is a Common Table Expression that references itself.

• It is used to perform recursive operations on hierarchical data.

• It consists of two parts: the anchor member and the recursive member.

• The anchor member is the base case and the recursive member is the recursive case.

• It can be used to traverse a tree structure or to calculate running totals.

• It can improve performance and simplify complex queries.

Output parameters are variables used to return values from a function or stored procedure.

• Output parameters are declared with the OUTPUT keyword in SQL Server.

• They can be used to return a single value or a table of values.

• Output parameters are useful for passing data between stored procedures or functions.

• They can also be used to return status codes or error messages.

Transactions ensure data consistency and integrity in a database.

• Allows multiple operations to be treated as a single unit of work

• Ensures that all operations are either committed or rolled back as a whole

• Prevents data inconsistencies and corruption

• Provides ACID properties to the database

• Example: transferring funds between bank accounts

• Example: updating inventory levels after a purchase

File groups are logical containers for database files that can be used to manage storage and backup operations.

• File groups allow for the organization of database files into logical units.

• They can be used to manage storage and backup operations.

• A database can have multiple file groups, each with its own set of files.

• File groups can be used to control the placement of data and indexes on different physical disks.

• File gro...read more

Magic tables are temporary tables created by SQL Server during DML operations.

• Magic tables are used to access the data before and after an INSERT, UPDATE, or DELETE operation.

• They are created automatically by SQL Server and cannot be modified by the user.

• The inserted and deleted tables are examples of magic tables.

• They are useful for auditing and logging changes to a database.

MERGE is a SQL command used to combine INSERT, UPDATE, and DELETE operations into a single statement.

• MERGE is used to synchronize two tables by inserting, updating, or deleting rows based on a specified condition.

• It is useful for data warehousing and ETL processes.

• MERGE can improve performance by reducing the number of round trips between the client and server.

• Syntax: MERGE INTO target_table USING source_table ON condi...read more

Temp tables are used to store intermediate results during query processing.

• Temp tables are created in tempdb database.

• They can be local or global.

• Local temp tables are only visible to the current session.

• Global temp tables are visible to all sessions.

• They can be created using SELECT INTO or CREATE TABLE statements.

• They can be used to store intermediate results during complex queries.

• They are automatically dropped when ...read more