Which TCP/IP port does SQL Server run on? How can it be changed?

SQL Server runs on port 1433. It can be changed from the Network Utility TCP/IP properties –> Port number.both on client and the server.

What is SQL Profiler?

SQL Profiler is a graphical tool that allows system administrators to monitor events in an instance ofMicrosoft SQL Server. You can capture and save data about each event to a file or SQL Server table toanalyze later. For example, you can monitor a production environment to see which stored procedures are hampering performance by executing too slowly.

What is the difference between a HAVING CLAUSE and a WHERE CLAUSE?

Specifies a search condition for a group or an aggregate. 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. Having Clause is basically used only with the GROUP BY function in a query. WHERE Clause is applied to each row before they are part of the GROUP BY function in a query.

Difference between Function and Stored Procedure?

UDF can be used in the SQL statements anywhere in the WHERE/HAVING/SELECT section where as Stored procedures cannot be. UDFs that return tables can be treated as another rowset. This can be used in JOINs with other tables. Inline UDF's can be though of as views that take parameters and can be used in JOINs and otherRowset operations.

What is difference between DELETE & TRUNCATE commands?

Delete command removes the rows from a table based on the condition that we provide with a WHEREclause. Truncate will actually remove all the rows from a table and there will be no data in the tableafter we run the truncate command.
TRUNCATE
TRUNCATE is faster and uses fewer system and transaction log resources than DELETE.TRUNCATE removes the data by deallocating the data pages used to store the table’s data, and only thepage deallocations are recorded in the transaction log.TRUNCATE removes all rows from a table, but the table structure and its columns, constraints, indexesand so on remain. The counter used by an identity for new rows is reset to the seed for the column.You cannot use TRUNCATE TABLE on a table referenced by a FOREIGN KEY constraint.Because TRUNCATE TABLE is not logged, it cannot activate a trigger.TRUNCATE can not be Rolled back.TRUNCATE is DDL Command.TRUNCATE Resets identity of the table.
DELETE
DELETE removes rows one at a time and records an entry in the transaction log for each deleted row.If you want to retain the identity counter, use DELETE instead. If you want to remove table definitionand its data, use the DROP TABLE statement.DELETE Can be used with or without a WHERE clauseDELETE Activates Triggers.DELETE Can be Rolled back.DELETE is DML Command.DELETE does not reset identity of the table.