We have a table with a CHARACTER data type field. We apply a “>” row comparison between this field and another CHARACTER field in another table. What will be the results for records with field value of NULL

This is something  so many asked me because I also faced the same situation before, so having a NULL in a row when compared will give an UNKNOWN result.

The result will not be correct hence creates an ambiguity.

Reference : Dilip Kumar Jena ( https://sqlexplore.wordpress.com)

SQL SERVER – What is @@Rowcount, @@Error and @@Identity

@@Rowcount is used to display the number of rows affected by last SQL statement.

@@Error displays the error number for the last SQL statement executed. The value is zero,if there is no error.

@@identity returns the last inserted identity value.

Reference : Dilip Kumar Jena ( https://sqlexplore.wordpress.com )

SQL SERVER 2008 – How to rename a column

There are many ways where in we can  rename  a column but what I prefer is using predefined stored Procedure sp_rename .

Syntax :

exec sp_rename ‘tablename.ColumnName’, ‘NewColumnName’, ‘column’ –objecttype

EX: changing the column name “Name” to “FirstName”

create table Personal(ID int, Name varchar(50))

EXEC sp_rename ‘Personal.Name’, ‘FirstName’, ‘column’

Output:

The message displayed is a caution message that says when we alter the column name there is a possibility that it can be used in one or more stored procedures so make sure you update everything and then only change the name .

Reference : Dilip Kumar Jena ( https://sqlexplore.wordpress.com )

SQL SEREVER – What is a View and An Indexed View

 A view  is a virtual tables that is made up of one or more tables. It can be used for security purpose, hiding complex queries.

An Indexed view is a view that has unique clustered index created on it. This takes physical storage i.e it stores data. It will be used in OLAP, decision support where inserts/updates are low. It can be used in the following scenarios

1) Joins and aggregation of big tables.

2) Repeated joins of the same tables on the same keys.

Reference : Dilip Kumar Jena ( https://sqlexplore.wordpress.com )

SQL SERVER 2008 – What is the difference betweeen Execute and sp_executesql

sp_executesql and Execute statement are used to execute a sql stored Procedure. The execute statement doesn’t support parameter substitution in the executed string.

According to Sql server Book Online Link Here.

‘To execute a string, we recommend that you use the sp_executesql stored procedure instead of the EXECUTE statement. Because this stored procedure supports parameter substitution, sp_executesql is more versatile than EXECUTE; and because sp_executesql generates execution plans that are more likely to be reused by SQL Server, sp_executesqlis more efficient than EXECUTE.’

So the best thing to use is sp_executesql but depends according to the requirement.

Reference : Dilip Kumar Jena ( https://sqlexplore.wordpress.com )

SQL SERVER – How many tables can SQL SERVER have and how many columns per table.

Sql server can have 2 billion tables per tables and 1024 columns per table.

Reference : Dilip Kumar Jena ( https://sqlexplore.wordpress.com )

SQL SERVER – What is the difference between static and dynamic sql

Static sql is compiled and optimized prior to its execution; dynamic is compiled and optimized during execution.

Reference : Dilip Kumar Jena ( https://sqlexplore.wordpress.com )