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SQL Interview Questions & Answers - Learning Mode
COOLINTERVIEW.COM DATABASE INTERVIEW QUESTIONS SQL INTERVIEW QUESTIONS QUESTIONS & ANSWERS - LEARNING MODE

SQL Interview Questions & Answers - Learning Mode

SQL (pronounced "ess-que-el") stands for Structured Query Language. SQL is used to communicate with a database. According to ANSI (American National Standards Institute), it is the standard language for relational database management systems. SQL consists of a data definition language, data manipulation language, and Data Control Language. The scope of SQL includes data insert, query, update and delete, schema creation and modification, and data access control. Although SQL is often described as, and to a great extent is, a declarative language (4GL), it also includes procedural elements.

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SQL Interview Questions & Answers - Learning Mode
Try SQL Interview Questions & Answers - Exam Mode
Question: What is the use of CASCADE CONSTRAINTS?

Answer: When this clause is used with the DROP command, a parent table can be dropped even when a child table exists. Source: CoolInterview.com
Question: Why does the following command give a compilation error?
DROP TABLE &TABLE_NAME;


Answer: Variable names should start with an alphabet. Here the table name starts with an '&' symbol. Source: CoolInterview.com
Question: What is the output of the following query
SELECT TRUNC(1234.5678,-2) FROM DUAL;


Answer: 1200. Source: CoolInterview.com
Question: What is the difference between TRUNCATE and DELETE commands?

Answer: TRUNCATE is a DDL command whereas DELETE is a DML command. Hence DELETE operation can be rolled back, but TRUNCATE operation cannot be rolled back.<br>WHERE clause can be used with DELETE and not with TRUNCATE. Source: CoolInterview.com
Question: what is the difference between replace and translate functions?

Answer: I Think here we r discussing abt SQL.Replace function is used to replace a string as well as character to another string or character,Translate function exists in ORACLE for translating single character to some other character........ Source: CoolInterview.com
Question: What are the advantages and disadvantages of primary key and foreign key in SQL?



Answer: Primary key

Advantages

1) It is a unique key on which all the other candidate keys are functionally dependent

Disadvantage

1) There can be more than one keys on which all the other attributes are dependent on.

Foreign Key

Advantage

1)It allows refrencing another table using the primary key for the other table
Source: CoolInterview.com
Question: What will be the output of the following query?
SELECT DECODE(TRANSLATE('A','1234567890','1111111111'), '1','YES', 'NO' );


Answer: NO.
Explanation :
The query checks whether a given string is a numerical digit. Source: CoolInterview.com
Question: How we get second highest salary in
database. Please show me this coding.


Answer: select top 1 from (select top 2 from (select salary from employee order by salary) order by salary dsc) Source: CoolInterview.com
Question: State true or false.
!=,
<>,
^=
all denote the same operation.


Answer: True. Source: CoolInterview.com
Question: Difference between decode and case.
in which case we are using case and in which case we are using decode?
with an example.



Answer: First I will give one example using 'decode'


sql>SELECT ENAME,SAL,DECODE(DEPTNO,10,'ACCOUNTING',20,'RESEARCH',30,'SALES',40,'OPERATIONS','OTHERS') "DEPARTMENTS" FROM EMP;


I have used the decode function on 'deptno' column. It will give the user-friendly output. instead of using 'accounting', 'research'.. We can use anything we want to get the friendly outputs.


I have to check-out the ' Source: CoolInterview.com
Question: Which date function is used to find the difference between two dates?

Answer: MONTHS_BETWEEN. Source: CoolInterview.com
Question: How can i hide a particular table name of our schema.



Answer: you can hide the table name by creating synonyms.

e.g) you can create a synonym y for table x

create synonym y for x;
Source: CoolInterview.com
Question: What is the difference between cross product & Cartesian product?

Answer: There is no difference between Cartesian product and cross join.
although there syntax are different but they work as a same.

Cartesian or cross product selects all rows from both the table.
example

tableA 6 rows
tableB 6 rows

Cartesian or cross product
36 rows.
Source: CoolInterview.com
Question: How to programmatically find out when the SQL Server service started?

Answer:
Question: What is a default TCP/IP socket assigned for SQL Server?

Answer: 1433 is default tcp/ip socket sql server. Source: CoolInterview.com
Question: What will be the output of the following query?
SELECT REPLACE(TRANSLATE(LTRIM(RTRIM('!! ATHEN !!','!'), '!'), 'AN', '**'),'*','TROUBLE') FROM DUAL;


Answer: TROUBLETHETROUBLE. Source: CoolInterview.com
Question: Difference between Stored Procedure and Trigger



Answer: Information related to Stored procedure you can see in USER_SOURCE,USER_OBJECTS(current user) tables.

Information related to triggers stored in USER_SOURCE,USER_TRIGGERS (current user) Tables.

Stored procedure can't be inactive but trigger can be Inactive.
Source: CoolInterview.com
Question: What is outer join?Explain with examples.

Answer: The Left Outer Join returns all the rows from the Left Table with the values that match with the Key from the second table.

The Right Outer Join returns all the rows from the Right Table with the values that match with the key from the first table. Source: CoolInterview.com
Question: What command is used to create a table by copying the structure of another table?

Answer: CREATE TABLE .. AS SELECT command
Explanation:
To copy only the structure, the WHERE clause of the SELECT command should contain a FALSE statement as in the following.
CREATE TABLE NEWTABLE AS SELECT * FROM EXISTINGTABLE WHERE 1=2;
If the WHERE condition is true, then all the rows or rows satisfying the condition will be copied to the new table. Source: CoolInterview.com
Question: How to delete same id in rows?
For example empid=5 repeated for times in rows. How to delete which sql query is used?


Answer: we can use distinct clause for this type of query.distinct clause is used to remove duplicates from table
like
select rowid distinct from table name
Source: CoolInterview.com

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Latest 20 Questions
Payment of time- barred debt is: (a) Valid (b) Void (c) Illegal (d) Voidable
Consideration is defined in the Indian Contract Act,1872 in: (a) Section 2(f) (b) Section 2(e) (c) Section 2(g) (d) Section 2(d)
Which of the following is not an exception to the rule, "No consideration, No contract": (a) Natural love and affection (b) Compensation for involuntary services (c) Completed gift (d) Agency
Consideration must move at the desire of: (a) The promisor (b) The promisee (c) The promisor or any other party (d) Both the promisor and the promisee
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Specific offer can be communicated to__________ (a) All the parties of contract (b) General public in universe (c) Specific person (d) None of the above
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A offers B to supply books @ Rs 100 each but B accepts the same with condition of 10% discount. This is a case of (a) Counter Offer (b) Cross Offer (c) Specific Offer (d) General Offer
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When an offer is made to the world at large, it is ____________ offer. (a) Counter (b) Special (c) General (d) None of the above
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A specific offer can be accepted by ___________. (a) Any person (b) Any friend to offeror (c) The person to whom it is made (d) Any friend of offeree
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