ESSENTIAL SQL INTERVIEW QUESTIONS 2018-LEARN NOW!
Q. What is SQL?
SQL- A Structured Query Language, It is also pronounced as “SEQUEL” and it an Non-procedural Language which is used to operate all relational database. Used for Database communication. Its a standard language that can be used to perform the tasks like data retrieval, data update, insert or delete data from an database.
Features of SQL:
Client server architecture,
Dynamic data definition,
Multiple views of data,
Complete database language,
Structure and SQL standards.
Q. About The SQL Buffer?
All Commands of SQL are Typed at the SQL prompt.
Only One SQL Statements is Managed in The SQL Buffer.
The Current SQL Statement Replaces the Previous SQL Statement in the Buffer.
The SQL Statement Can be Divided Into Different Lines Within The SQL Buffer.
Only One Line i.e., The Current Line Can be Active at a Time in the SQL Buffer.
At SQL Prompt, Editing is Possible Only in The Current SQL Buffer Line.
Every Statement of SQL should be terminated Using Semi Colon ”;”
One SQL Statement can Contain Only One Semo Colon.
To Run the Previous OR Current SQL Statement in the Buffer Type “/” at SQL Prompt.
To Open The SQL Editor Type “ED” at SQL Prompt.
Q. What are Important SQL Functions?
It Converts Alpha Character Values to Lower Case.
The Return Value Has The Same Data Type as Argument CHAR Type (CHAR or VARCHAR2)
It Converts the Alpha Character Values to Upper Case.
The Return Value Has The Same Data Type as Argument CHAR.
It Converts Alpha Character Values into Upper Case For The First Letter of Each Word, keeping all Other Letter in Lower Case.
Words are Delimited by White Space or Characters That are Not Alphanumeric
Pads The Character Value Right Justified to a Total Width of ‘n’ Character Positions.
The Default Padding Character in Space.
Pads the Character Value Left Justified to a Total Width of ‘n’ Character ositions.
The Default Padding Character is Space.
It Enables to TRIM Heading Character From a Character String.
All The Leftmost Character That Appear in The SET are Removed.
It Enables the Trimming of Trailing Character From a Character STRING.
All the Right Most Characters That Appear in The Set are Removed.
It Enables to TRIM Heading or Trailing Character or Both From a Character String.
If LEADING is Specified Concentrates On Leading Characters.
If TRAILING is Specified Concentrates on Trailing Characters.
If BOTH OR None is Specified Concentrates Both on LEADING and TRAILING.
Return the VARCHAR2 Type.
Q. How to Open SQL Server?
Goto -> Start -> All Programms -> Microsoft SQL Server 2008 R2 -> SQL Server management Studio.
Q. What is SQL Injections? And How to Prevent SQL Injection Attacks?
It is a mechanism of getting secure data from database.
SQL Injection Attacks::
By providing proper validations for input fields.
By using parameterised queries.
By using stored procedures
By using frequent code reviews
We must not display database error messages in frontend
SQL injection is a code injection technique, used to attack data-driven applications.
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