Computer Science-spl QUESTIONS and Answers exams contains the questions from various competitive exams.These questions are the part of previous year paper.These kind of questions would be helpful in preparing for exams like IAS, PCS, UPSC, NDA, CDS SSC, RRB, PSC, IBPS
Answer:Primary keys are the unique identifiers for each row. They must contain unique values and cannot be null. Due to their importance in relational databases, Primary keys are the most fundamental aspect of all keys and constraints. A table can have only one primary key.
Foreign keys are a method of ensuring data integrity and manifestation of the relationship between tables.
Answer:Collation refers to a set of rules that determine how data is sorted and compared. Character data is sorted using rules that define the correct character sequence with options for specifying case sensitivity, accent marks, Kana character types, and character width.
What is S3? What is it used for? Should encryption be used?
Answer:S3 stands for Simple Storage Service. You can think of it like ftp storage, where you can move files to and from there, but not mount it like a filesystem. AWS automatically puts your snapshots there, as well as AMIs there. Encryption should be considered for sensitive data, as S3 is a proprietary technology developed by Amazon themselves, and as yet unproven vis-a-vis a security standpoint.
Scripting can even go further if the page author desires. For example, the author may include a preference screen that lets the user determine the desired background and text color combination. A script can save this information on the client in a well-regulated local file called a cookie. The next time the user comes to the site, scripts in its pages look to the cookie info and render the page in the color combination selected previously. The server is none the wiser, nor does it have to store any visitor-specific information.
Answer:AMI stands for Amazon Machine Image. It is effectively a snapshot of the root filesystem. Commodity hardware servers have a bios that points the the master boot record of the first block on a disk. A disk image though can sit anywhere physically on a disk, so Linux can boot from an arbitrary location on the EBS storage network.
What is User-defined Functions? What are the types of User-defined Functions that can be created?
Answer:User-defined Functions allow defining its own T-SQL functions that can accept zero or more parameters and return a single scalar data value or a table data type.
Different Types of User-Defined Functions created are as follows:
Scalar User-defined Function
A scalar user-defined function returns one of the scalar data types. Text, ntext, image and timestamp data types are not supported. These are the type of user-defined functions that most developers are used to in other programming languages.
Inline Table-Value User-defined Function
An Inline table-value user-defined function returns a table data type and is an exceptional alternative to a view as the user-defined function can pass parameters into a T-SQL select command and in essence provide us with a parameterized, non-updateable view of the underlying tables.
Multi-Statement Table-Value User-defined Function
A multi-statement table-value user-defined function returns a table, and it is also an exceptional alternative to a view as the function can support multiple T-SQL statements to build the final result where the view is limited to a single SELECT statement. Also, the ability to pass parameters into a T-SQL select command or a group of them gives us the capability to in essence create a parameterized, non-updateable view of the data in the underlying tables. Within the create function command, you must define the table structure that is being returned. After creating this type of user-defined function, It can be used in the FROM clause of a T-SQL command unlike the behavior encountered while using a stored procedure which can also return record sets.
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