MS SQL DBA Interview Questions and Answers
Interview questions for database developers and software developers frequently include SQL Server-related inquiries. The most common MS SQL Server interview questions and answers are listed below. This questions and answers guide also provides solutions to queries about security, query optimization, and database design. Enroll in our SQL Server training in Chennai and enhance your DBA skills.
By DBMS, what do you mean? What varieties exist within it?
A structured data collection system is called a database. A user can communicate with a database through a DBMS. Any kind of data—strings, numbers, photos, and so on—can be added, removed, and altered from the database.
Two different kinds of DBMS exist:
RDBMS: Tables, or relations, are used to hold data in relational database management systems. MySQL is one example.
Non-RDBMS: Relationships, tuples, and attributes are not concepts in a non-relational database management system. MongoDB is one example.
RDBMS: What is it?
Relation Database Management Systems (RDBMS) is the abbreviation for RDBMS. RDBMS features include the following:
Write-intensive operations: Transaction-oriented applications and frequent writing to the RDBMS are commonplace.
Historical or real-time data: The RDBMS is built to manage constantly changing data. Alternatively, RDBMSs may store enormous amounts of historical data, which can subsequently be “mined” or studied.
Application-specific schema: Every application has its own schema, and each RDBMS configuration is particular to that application.
Complex data models: The RDBMS’s relational architecture enables it to handle intricate, complex data models that call for several tables, foreign key values, intricate join procedures, and other features.
Data integrity: The RDBMS has some parts that are intended to guarantee data integrity. Referential integrity, rollback operations, and transaction-oriented operations fall under this category. Explore more about RDBMS vs. NoSQL
SQL: What is it?
Programming languages such as Structured Query Language (SQL) are used to access and manipulate relational database management systems (RDBMSs). Popular RDBMSs like SQL Server, Oracle, and MySQL all make extensive use of SQL. A query is the smallest SQL execution unit. Data can be chosen, updated, and deleted using SQL queries.
What distinguishes MySQL from SQL?
Structured Query Language, or SQL for short, is a standard language based on the English language. The relational database’s central component, SQL, is used to access and manage databases. Meanwhile, a database management system is called MySQL. An RDMS like Informix, SQL Server, and others is MySQL.
Describe a Self-Join.
One kind of join that can be used to join two tables is a self-join. It is therefore a unique relationship. The table’s rows are joined to one another and every other row in the same table uses a self-join. Because of this, combining and comparing rows from the same database table is the main use for a self-join. View and materialized view are the important things.
What is the SELECT statement?
Zero or more rows are obtained from one or more database tables or views by using the SELECT command. In most applications, the most common data manipulation language (DML) command is SELECT. Due to the declarative nature of SQL, SELECT queries specify a result set but not how to calculate it.
List the many kinds of SQL relationships.
The database has several kinds of relationships:
A one-to-one relationship is one in which every record in one table is equivalent to the maximum of every record in the other.
The most common type of connection is one-to-many or many-to-one when a record in one table is linked to multiple records in another.
When defining a relationship that needs several instances on both ends, the term “many-to-many” is used.
Self-Referencing Relationships: This is the technique to use when a table has to establish a relationship with itself. Learn about primary keys and foreign keys in SQL.
Denormalization: What is it?
The inverse of normalization is called denormalization; it involves adding redundant data to speed up complex searches involving the joining of many tables. Redundant copies of data are added or grouped in an attempt to optimize a database’s read performance.
What do SQL joins do?
In SQL, joins are used to merge rows from one or more tables according to a shared column. Depending on the connection between the tables, several joins can be utilized to retrieve data. Four different kinds of joins exist inner join, left join, right join, and full join.
Define outer join with an example
Right/Outer Join: To obtain all the rows or records from the right and the matching ones from the left, utilize the right join.
FROM Table_A A
RIGHT JOIN Table_B B
ON A.col = B.col;
When you talk about attributes, what do you mean by their types?
The items that create master data service entities are called attributes. Additionally, the members of the object are described using attribute values.
Three categories of qualities exist, as follows:
- Free-form attributes
- Domain-based attributes
- File attributes
Why is a transaction log significant, and what does it mean?
Every transaction and any associated database alterations are recorded in the transaction log. To be more exact, it keeps track of a transaction’s start, modifications made throughout, and final commit or rollback. Because it is used to restore the database to a consistent state in the event of a system failure, the transaction log is one of the most important parts of database management.
Useful Link: String Manipulation Functions in SQL
A Recursive Stored Procedure: What Is It?
When a stored procedure includes a CALL statement in the procedure body, it becomes recursive. It is possible to nest the call statements here. Recursions have no upper bound, although the layering of stored procedures is 15 times limited. Furthermore, mutual recursion and chain recursion are the two types of recursive stored procedures.
What do denormalization and normalization of databases mean?
The practice of reorganizing a relational database to lessen data redundancy and enhance data integrity is known as database normalization. Conversely, denormalization is a reverse engineering procedure that aids in improving a database’s read performance. Either grouping the data or adding copies of the data is how it is done. As a result, reading data takes less time.
What do SQL Server defaults mean?
The value entered for a field in a database table is its default. Unless another value is supplied, this value will be repeated in all new records for the column. To specify a default value in this context, utilize SQL Server Management Studio. Be aware that we can only set defaults for databases that are currently in use, and that if a default value grows larger than the column, it may be truncated.
Suggested Link: Types of SQL Server Indexes
Describe cursors and list the different kinds.
It is well known that cursors are extensions that lead to sets, which are collections of rows returned for a given statement. They assist in removing one or more row blocks from the current location. They can also facilitate data updates for the rows in the result set that are currently in that position. The four types of cursors are listed below:
- Forward only
By CTE, what do you mean?
Common Table Expression is the representation of CTE. The temporary result set is specified. Simple queries are run to retrieve this collection of results. SELECT, INSERT, UPDATE, DELETE, and MERGE commands can all make reference to CTE. Furthermore, VIEW statements can also make use of CTE. CTE comes in two flavors: recursive and non-recursive.
SQL Server Profiler: What is it?
It is a graphical user interface designed to monitor a database engine instance. When there is a demand, it generates, maintains, and evaluates traces as well as their outcomes. Trace files typically capture events that can be played back to diagnose problems like slow-running queries, identify the source of errors, etc.
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What does SQL Server’s BULK COPY mean?
A lot of data can be transferred in and out of SQL tables or views using BULK COPY. It also permits data transfer between an operating system data file, such as ASCII files, and a SQL server.
In SQL Server, there are four different ways to perform BULK COPY:
- Bulk copy from a table or view into another table or view in the same format using the native mode data file.
- Data file in character mode: bulk copy data in a different format from one table or view to another table.
- Transferring data in bulk from a file into a table or view
- Loading data in bulk into a table or display after first loading it into program variables.
Which types of backups do SQL servers use?
Copy-only backup: It is a separate backup for specific purposes from the routine backups.
Data backup: It is a full or partial backup of the data.
Database backup: It is an entire database backup.
Differential backup: Following a database backup event, it is a record of just the modifications made to the database.
Full backup: It is a complete data backup that includes the transaction log required for recovery.
Log backup: This is a complete transaction log backup.
File backup: It is a database’s file backup.
Partial backup: It consists of the primary, all read/write, and optionally defined read-only files from a particular filegroup.
Related Source: Oracle Interview Questions and Answers
This concludes the blog post about SQL interview questions. With any luck, you will ace the job interview with this set of MS SQL DBA Interview Questions and Answers. Check out SLA Jobs’ SQL Certification Course in Chennai if you want to learn Microsoft SQL Server and pursue a career in relational databases.