What is a deadlock “GRANT” and “REVOKE’ statements in SQL Server

What is a deadlock in SQL Server?

Deadlock is a situation when two processes, each having a lock on one piece of data, attempt to acquire a lock on the other’s piece. Each process would wait indefinitely for the other to release the lock, unless one of the user processes is terminated.

Add default value to existing column (SQL)

In SQL Server there are two ways to add a column with a default value.



Add Default Value to Existing Column

Using SQL Data Definition Language (DDL) to Create Data Tables and Other Database Objects

Using the CREATE TABLE Statement to Create Tables

Tables are the primary structures used to hold data in a relational database. In a typical multi-user environment, the database administrator (dba) creates the tables that serve as the data stores for the organization's data. Users normally create their own temporary tables used to store data extracted from the main organizational tables.

What is meant cluster and Non cluster index?

A clustered index is a special type of index that reorders 
the way records in the table are physically stored. 
Therefore table can have only one clustered index. The leaf 
nodes of a clustered index contain the data pages.

Difference between HAVING and WHERE Clause

Answer in one line is : HAVING specifies a search condition for a group or an aggregate function used in SELECT statement.

HAVING can be used only with the SELECT statement. HAVING is typically used in a GROUP BY clause. When GROUP BY is not used, HAVING behaves like a WHERE clause.

Delete Duplicate Records – Rows

Following code is useful to delete duplicate records. The table must have identity column, which will be used to identify the duplicate records. Table in example is has ID as Identity Column and Columns which have duplicate data are DuplicateColumn1, DuplicateColumn2 and DuplicateColumn3.