Common SQL Questions

.Write an SQL Query to find first weekday of the month?

SELECT 

DATENAME(dw, DATEADD(dd,  -DATEPART(dd, GETDATE()) + 1, GETDATE())) 

AS FirstDay

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A relationship in DBMS is the scenario where two entities are related to each other. In such a scenario, the table consisting of foreign key references to that of a primary key of the other table.

The different types of relationships in DBMS are as follows:

• One-to-One Relationship –  Used when a single row in Table A is related to a single row in Table B.
• One-to-Many Relationship – Used when a single row in Table A is related to many rows in table B.
• Many-to-Many Relationship – Used when many rows in table A can be related to many rows in table B.
• Self -Referencing Relationship – Used when a record in table A is related to record in same table.

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A user-defined function is a function written as per the needs of the user by implementing logic. In these kinds of functions the user is not limited to pre-defined functions and simplify the complex code of predefined function by writing simple code. This function returns a scalar value or a table

.

CREATE FUNCTION samplefunc(@num INT)

RETURNS TABLE

AS

RETURN SELECT * FROM customers WHERE CustId=@num

SELECT * FROM samplefunc(10)

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Mention the differences between SUBSTR and CHARINDEX in SQL Server.

SUBSTR	CHARINDEX
Used to return a specific portion of the string in a given string	Used to return a character position in a given specified string
Example:SUBSTRING(‘Edureka’,1,4) Output:Edur	Example:CHARINDEX(‘r’,’Edureka’,1) Output:4