What’s the difference between a primary key and a unique key?
Both primary key and unique enforce uniqueness of the column on which they are defined. But by default primary key creates a clustered index on the column, where... Read more »
‘SQL Interview Questions’ - KyaPoocha.com
What is an Index?
When queries are run against a db, an index on that db basically helps in the way the data is sorted to process the query for faster and data retrievals are much... Read more »
Where do you think the users names and passwords will be stored in sql server?
They get stored in master db in the sysxlogins table. Read more »
What is lock escalation?
Lock escalation is the process of converting a lot of low level locks (like row locks, page locks) into higher level locks (like table locks). Every lock is a memory... Read more »
Let us say the SQL Server crashed and you are rebuilding the databases including the master database what procedure to you follow?
For restoring the master db we have to stop the SQL Server first and then from command line we can type SQLSERVER –m which will basically bring it into the maintenance... Read more »
What is Livelock?
A livelock is one, where a request for an exclusive lock is repeatedly denied because a series of overlapping shared locks keeps interfering. SQL Server detects... Read more »
What are statistics, under what circumstances they go out of date, how do you update them?
Statistics determine the selectivity of the indexes. If an indexed column has unique values then the selectivity of that index is more, as opposed to an index with... Read more »
What is database replicaion? What are the different types of replication you can set up in SQL Server?
Replication is the process of copying/moving data between databases on the same or different servers. SQL Server supports the following types of replication scenarios: *... Read more »
Why does my inline or embedded SQL run faster than my stored procedures?
ecompilations might be the source of the slower stored procedure speed. To find out for sure, you need to do some performance investigation, such as looking at Showplans... Read more »
What is difference between ‘Count’ and ‘Count(*)’?
The Difference between ‘Count’ and ‘Count(*)’ A. ‘Count’: Counts the number of non-null values. ‘Count(*)’: Counts the number of rows in the table,... Read more »
What are the pros and cons of creating extended stored procedures?
The pros are that you can implement additional functionality and access data from DLLs from within SQL Server. If you need to do something that can be done only... Read more »
What are the benefits of SQL ?
1. It is flexible, Powerful and easy to learn. 2. It is a non-procedural language. It a] Processes set of records rather than just one at a time and b] Provides... Read more »
What are the different types of SQL commands ?
DDL ( Data definition language ) DML ( Data manipulation language ) TCL ( Transact control language) Session Control Statements. ( ALTER SESSION, ROLE ) System... Read more »
What are CLUSTERS ?
A CLUSTER is a means of storing together data from multiple tables, when the data in those tables contains information and is likely to be accessed concurrently. Read more »
What is a SEGMENT ?
A SEGMENT is another way to classify the space allocated to a table, index, or cluster. A table has one segment that consists of all of its extents. Every index... Read more »
What are Packages ?
A PACKAGE is a PL/SQL object that groups PL/SQL types, variables, SQL cursors, exceptions,procedures, and functions.Each package has a specification and a body.... Read more »
What are Hash clusters ?
Hash clusters are also cluster table data in a manner similar to normal clusters. However, a row is stored in a hash cluster based on the result of applying a hash... Read more »
What are Extents?
The next level of logical database space is called an extent. An extent is a specific number of contiguous data blocks, obtained in a single allocation, used to... Read more »
Explain the Memory Structures of the Oracle database ?
Oracle creates and uses memeory sructures to complete several jobs. For example, memory is used to store program code being executed and data that is shared among... Read more »
What are OPTIMIZER HINTS ?
Specifies a hint string that Oracle Forms passes on to the RDBMS optimizer when constructing queries. Using the optimizer can improve the performance of database... Read more »