Skip to main content

Interview Questions and answers - SQL Server Day 3

Question:  What is difference between Function and Stored Procedure in SQL Server?

Answer: Some basic difference between stored procedure and function is described below.

The main difference between stored procedure and function is Function must returns a value while stored procedure can or not this is optional. Function can have input parameter only while stored procedure can have both input/output parameters. Function can be called from stored procedures but stored procedures can’t call from function. 

Stored Procedure
Function must returns a value
In stored procedure it is optional 
Function can have input parameter only
Stored procedure can have both input and output parameter s
Function can be called from procedure
Procedure can‘t be called from function
Function allows only select statement
Procedure allows DML statement(SELECT, INSERT, UPDATE, DELETE)
Function can use in SQL statement like WHERE/HAVING/SELECT
Procedure can’t be use in SQL statement like WHERE/HAVING/SELECT
Function can return table and can be treated as another row set. This can be use in joins with other tables.
Transaction can’t be implement
Transaction can be implement in stored procedure

Question: What is subquery in SQL server?

Answer: A SELECT statement query nested in another t-SQL  statement is called subquery. SELECT subquery always run independently and return result set to t-SQL statement. Subquery doesn't depend on statement in which it is nested.

Question: What are different types of joins in SQL Server?

Answer: Types of joins in SQL Server is given bellow.
1- Cross join
2- Inner join
3- Outer join
    a)Left Outer join
    b)Right Outer join
    c)Full Outer join
4- Self join

Question: What is Cross Join in SQL Server?

Answer: Joins between tables without conditions produces the Cartesian  product called cross join. The size of Cartesian product result set is the number of rows in the first table multiplied by the number of rows in the second table.


SELECT p.bID, t.Name AS Territory
FROM Sales.SalesPerson p
CROSS JOIN Sales.SalesTerritory t

Question: What is inner join in SQL Server?

Answer: Inner join display only the rows of tables which matched in both joined table on a particular column. This is the default type of join in the query.

Question: What is Outer join and it type in SQL Server?

Answer: Outer join includes related and rows and also not related rows. there are three type of outer joins in SQL Server.
a) Left Outer Join: the Left Outer join display all the rows of first table and all matched rows of second table but not appears unmatched rows of second table.
b) Right Outer join: Right Outer joined display all the row of second table and matched rows of first table but not appears unmatched rows if first table.
c) Full Outer Join: Full Outer join display all the rows of joined tables whether they matched or not.

Question: What is Self join in SQL Server?

Answer: Join between a table and it's alias is called self join. In this join table join itself but same name may create confusion so we used alias of table as second table.

Popular posts from this blog

Check for changes to an SQL Server table?

Problem: Suppose your team is working on the under-development project so it might be possible continuous work on the database and perform changes in Table, Stored procedure as per requirement, and daily you have to update the testing server database as per changes are done in developing server database then how it is possible to trace those changes. There are a lot of solutions for this problem which is listed below Solution 1: For SQL Server 2000, 2005 and above use the CHECKSUM command SELECTCHECKSUM_AGG(BINARY_CHECKSUM(*))FROMYour_Table_NameWITH (NOLOCK); That will return the same number each time its run as long as the table contents haven't changed. Unfortunately CHECKSUM does not work always properly to detect changes. It is only a primitive checksum and no CRC calculation. Therefore you can't use it to detect all changes, e. g. symmetrical changes result in the same CHECKSUM! Solution 2: 1.Run the following query. Before executing query replace DB_Name with your database name…

How to drop multiple tables with common prefix in one query?

Problem: Suppose we have a situation where we need to drop those tables that have some prefixes string, so it is possible to drop those tables with a common prefix in a single query.
Solution: yes it is possible to drop all those tables that have the common prefix in a single query. Using following query you can delete all those tables that begin with a certain prefix string. In where condition just put the common prefix string in where condition (Like ‘prefix%’)
SELECT@query+=' DROP TABLE ' +QUOTENAME( +'.'+QUOTENAME(';' FROMsys.tablesASt INNERJOINsys.schemasASs ONt.[schema_id]=s.[schema_id] WHEREt.nameLIKE'MX_100%';
This query may create an issue, if a table has a foreign key relationship, you'll either need to drop them first or arrange the output to drop the tables in a certain order. If you want to monitor exactly what goes on when the query is running then use the following que…

Merge and Merge join transformation in SSIS