10+ SQL Server Developer Interview Questions and Answers

WHERE clause is used to filter rows before grouping, HAVING clause is used to filter groups after grouping.

• WHERE clause is used with SELECT, UPDATE, DELETE statements to filter rows based on a condition.

• HAVING clause is used with SELECT statement to filter groups based on a condition.

• WHERE clause is applied before the data is grouped, HAVING clause is applied after the data is grouped.

• Example: SELECT * FROM table_name WHERE column_name = 'value';

• Example: SELECT column_name, C...read more

Different types of SQL joins with given data sets a and b.

• Inner join: Returns rows where there is a match in both tables (1,1)

• Left join: Returns all rows from the left table and the matched rows from the right table (1,1,1,2,2)

• Right join: Returns all rows from the right table and the matched rows from the left table (1,1,2,4)

• Cross join: Returns the Cartesian product of the two tables (1,1,1,1,1,2,1,4,1,1,2,1,2,2,1,4,2,1,2,2,2,2,4,3,1,1,3,1,2,3,1,4,3,1,1,3,2,2,3,2,4,3,1,2,3,2,...read more

I approach salary negotiation by researching industry standards, highlighting my skills and experience, and being open to compromise.

• Research industry standards for salary range

• Highlight relevant skills and experience that justify desired salary

• Be open to compromise and negotiate based on overall compensation package

• Consider other benefits besides salary, such as flexible work hours or professional development opportunities

Indexes are data structures that improve the speed of data retrieval operations in a database.

• Indexes are used to quickly locate data without having to search every row in a database table.

• Types of indexes include clustered, non-clustered, unique, and composite indexes.

• Clustered indexes determine the physical order of data in a table, while non-clustered indexes store a separate copy of the indexed columns.

• Unique indexes ensure that no two rows have the same values in the ind...read more

Primary key uniquely identifies each record in a table, while Unique key allows only one instance of a value in a column.

• Primary key does not allow NULL values, while Unique key allows one NULL value.

• Primary key automatically creates a clustered index, while Unique key creates a non-clustered index by default.

• Primary key can be referenced by foreign keys, while Unique key cannot be referenced by foreign keys.

row_number, rank, dense_rank are window functions in SQL used to assign a unique number to each row based on specified criteria.

• row_number() assigns a unique sequential integer starting from 1 to each row in the result set

• rank() assigns a unique rank to each row based on the specified ordering criteria, with gaps in ranking for ties

• dense_rank() assigns a unique rank to each row based on the specified ordering criteria, with no gaps in ranking for ties

SQL query to retrieve the maximum salary for each department

• Use the MAX() function to find the maximum salary

• Group the results by department using the GROUP BY clause

• Join the employee table with the department table to get the department information

Integrity constraints are rules that ensure data integrity and consistency in a database.

• Integrity constraints are used to enforce business rules and maintain data accuracy.

• Common types of integrity constraints include primary key, foreign key, unique key, and check constraints.

• For example, a primary key constraint ensures that each row in a table is uniquely identified by a specific column or combination of columns.

DML commands are Data Manipulation Language commands used to manage data in a database.

• DML commands include INSERT, UPDATE, DELETE, and SELECT.

• INSERT is used to add new rows of data into a table.

• UPDATE is used to modify existing data in a table.

• DELETE is used to remove rows of data from a table.

• SELECT is used to retrieve data from a database.

Types of joins in SQL are Inner Join, Left Join, Right Join, and Full Join.

• Inner Join: Returns rows when there is a match in both tables.

• Left Join: Returns all rows from the left table and the matched rows from the right table.

• Right Join: Returns all rows from the right table and the matched rows from the left table.

• Full Join: Returns rows when there is a match in one of the tables.

A stored procedure is a precompiled collection of SQL statements that can be executed by calling the procedure name.

• Stored procedures can accept input parameters and return output parameters.

• They can be used to encapsulate complex logic and improve performance by reducing network traffic.

• Stored procedures are stored in the database and can be reused by multiple applications or users.

• Example: CREATE PROCEDURE GetEmployeeDetails AS SELECT * FROM Employees WHERE Department = 'IT...read more

SQL commands are instructions used to interact with a database management system to perform tasks such as querying, updating, and managing data.

• SQL commands are used to perform various operations on a database, such as selecting data with SELECT, inserting data with INSERT, updating data with UPDATE, and deleting data with DELETE.

• Other common SQL commands include CREATE TABLE for creating tables, ALTER TABLE for modifying tables, and DROP TABLE for deleting tables.

• SQL command...read more

A trigger is a special type of stored procedure that automatically executes when certain events occur in a database.

• Triggers can be used to enforce business rules, maintain referential integrity, and automate repetitive tasks.

• Examples of trigger events include INSERT, UPDATE, and DELETE operations on a table.

• Triggers can be defined to execute before or after the triggering event.

Join is used to combine rows from two or more tables based on a related column between them.

• Join is used to retrieve data from multiple tables in a single query.

• Types of joins include Inner Join, Left Join, Right Join, and Full Outer Join.

• Join conditions are specified using the ON keyword.

• Example: SELECT * FROM table1 INNER JOIN table2 ON table1.column = table2.column;

• Joins can also be nested to combine more than two tables.

Different types of joins in SQL include inner join, left join, right join, and full outer join.

• Inner join: Returns rows when there is a match in both tables.

• Left join: Returns all rows from the left table and the matched rows from the right table.

• Right join: Returns all rows from the right table and the matched rows from the left table.

• Full outer join: Returns rows when there is a match in either table.

The key of reusability in SQL Server development is creating modular, efficient code that can be easily adapted and reused.

• Use stored procedures and functions to encapsulate logic for reuse.

• Implement common table expressions (CTEs) to simplify complex queries that are used frequently.

• Utilize user-defined data types and user-defined functions to standardize data processing tasks.

• Leverage views to encapsulate complex queries and make them reusable across multiple queries or rep...read more