1.What does COMMIT do ?
Ans: COMMIT makes permanent the changes resulting from all SQL statements in the transaction. The changes made by the SQL statements of a transaction become visible to other user sessions transactions that start only after transaction is committed.
2.What does ROLLBACK do ?
Ans: ROLLBACK retracts any of the changes resulting from the SQL statements in the transaction.
3.What's the maximum size of a row?
Ans: 8060 bytes.
4.What is lock escalation?
Ans: Lock escalation is the bassically use for the converting a lot of low level locks like a row lock or the level locks into higher level locks which is like table locks. Every lock is a memory structure too many locks would mean, more memory being occupied by locks. To prevent this from happening, SQL Server escalates the many fine-grain locks to fewer coarse-grain locks.
5.What is denormalization and when would you go for it?
Ans: denormalization is the reverse process of normalization it is also indate the name of denenormalisaiotn . It's maily use for the controlled introduction of redundancy in to the database design. It helps improve the query performance as the number of joins could be reduced.
6.What are the Different methods of loading Dimension tables?
Ans: There are many diffenrt of ways are there which is two different ways to load data in dimension tables.
1. Direct (Fast) : It is the bassically use for the loading purpose in this way All the constraints and keys are can be disabled before the data is loaded. Once a tym data is loaded, it is validated against all the constraints and keys. If data is found invalid or dirty it is not included in index and all future processes are skipped on this data.
2. Conventional (Slow) : It is bassically for the All the constraints and keys are validated against the data before, it is loaded, this way data integrity is maintained.
7.What is ER Diagram?
Ans: ER Diagrame is stands for tEntity Relationship Diagrams , It is the bassically a major data modelling tool . A type of diagram used in data modeling for relational data bases. These diagrams show the structure of each table and the links between tables. and It will also help organize the data in our project into entities and define the relationships between the entities. This process has proved to enable the analyst to produce a good database structure so that the data can be stored and retrieved in a most efficient manner. An entity-relationship (ER) diagram is a specialized graphic that illustrates the interrelationships between entities in a database.
8.What is surrogate key?
Ans: Surrogated keys are always integer or numeric. It is useful because the natural primary key can change and this makes updates more difficult .Surrogate key is the bassically a type of sunsitution key for the primary key . It is just a unique identifier or number for each row that can be used for the primary key to the table. The only requirement for a surrogate primary key is that it is unique for each row in the table..
9.What do you mean by Snow schema?
Ans: Snow Schema is the bassically known as snow flake schema, Its mainly interlinked or may have one to many relationship with other tables. This schema is normalized and results in complex join and very complex query as well as slower results.
10.What do you mean by Star schema?
Ans: Star Schema is bassically use for got a faster results becouse it is a single fact table with N number of Dimension, which will be linked directly with a fact table. This schema is De-normalized and results in simple join and less complex query as well as faster results.
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Ans: COMMIT makes permanent the changes resulting from all SQL statements in the transaction. The changes made by the SQL statements of a transaction become visible to other user sessions transactions that start only after transaction is committed.
2.What does ROLLBACK do ?
Ans: ROLLBACK retracts any of the changes resulting from the SQL statements in the transaction.
3.What's the maximum size of a row?
Ans: 8060 bytes.
4.What is lock escalation?
Ans: Lock escalation is the bassically use for the converting a lot of low level locks like a row lock or the level locks into higher level locks which is like table locks. Every lock is a memory structure too many locks would mean, more memory being occupied by locks. To prevent this from happening, SQL Server escalates the many fine-grain locks to fewer coarse-grain locks.
5.What is denormalization and when would you go for it?
Ans: denormalization is the reverse process of normalization it is also indate the name of denenormalisaiotn . It's maily use for the controlled introduction of redundancy in to the database design. It helps improve the query performance as the number of joins could be reduced.
6.What are the Different methods of loading Dimension tables?
Ans: There are many diffenrt of ways are there which is two different ways to load data in dimension tables.
1. Direct (Fast) : It is the bassically use for the loading purpose in this way All the constraints and keys are can be disabled before the data is loaded. Once a tym data is loaded, it is validated against all the constraints and keys. If data is found invalid or dirty it is not included in index and all future processes are skipped on this data.
2. Conventional (Slow) : It is bassically for the All the constraints and keys are validated against the data before, it is loaded, this way data integrity is maintained.
7.What is ER Diagram?
Ans: ER Diagrame is stands for tEntity Relationship Diagrams , It is the bassically a major data modelling tool . A type of diagram used in data modeling for relational data bases. These diagrams show the structure of each table and the links between tables. and It will also help organize the data in our project into entities and define the relationships between the entities. This process has proved to enable the analyst to produce a good database structure so that the data can be stored and retrieved in a most efficient manner. An entity-relationship (ER) diagram is a specialized graphic that illustrates the interrelationships between entities in a database.
8.What is surrogate key?
Ans: Surrogated keys are always integer or numeric. It is useful because the natural primary key can change and this makes updates more difficult .Surrogate key is the bassically a type of sunsitution key for the primary key . It is just a unique identifier or number for each row that can be used for the primary key to the table. The only requirement for a surrogate primary key is that it is unique for each row in the table..
9.What do you mean by Snow schema?
Ans: Snow Schema is the bassically known as snow flake schema, Its mainly interlinked or may have one to many relationship with other tables. This schema is normalized and results in complex join and very complex query as well as slower results.
10.What do you mean by Star schema?
Ans: Star Schema is bassically use for got a faster results becouse it is a single fact table with N number of Dimension, which will be linked directly with a fact table. This schema is De-normalized and results in simple join and less complex query as well as faster results.
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