SQL Server is a powerful relational database management system that is widely used in the industry. It provides a robust platform for storing, managing, and retrieving data. In this article, we will explore some important concepts and ideas related to SQL Server.

1. SQL Server Agent

SQL Server Agent plays a crucial role in the day-to-day tasks of a database administrator (DBA). It is often overlooked as one of the main tools for SQL Server management. Its purpose is to ease the implementation of tasks for the DBA, with its full-function scheduling engine, which allows you to schedule your own jobs and scripts.

2. Stored Procedure Recursion

SQL Server supports recursion, which means that stored procedures can call themselves. Recursion is a method of problem-solving where the solution is arrived at by repetitively applying it to subsets of the problem. This feature is particularly useful for performing numeric computations that require repetitive evaluation.

3. Log Shipping

Log shipping is a process that automates the backup of database and transaction log files on a production SQL server, and then restores them onto a standby server. This feature is available only in the Enterprise Edition of SQL Server. Log shipping provides a reliable disaster recovery plan by automatically backing up transaction logs throughout the day and restoring them on the standby server at defined intervals.

4. Counting Records in a Table

There are several ways to get an accurate count of the number of records in a table. You can use the following queries:


SELECT COUNT(*) FROM table1;
SELECT rows FROM sysindexes WHERE id = OBJECT_ID('table1') AND indid < 2;


5. Quoted Identifier

The QUOTED_IDENTIFIER setting determines how identifiers and literals are delimited in SQL Server. When QUOTED_IDENTIFIER is ON, identifiers can be delimited by double quotation marks, and literals must be delimited by single quotation marks. When QUOTED_IDENTIFIER is OFF, identifiers cannot be quoted and must follow all Transact-SQL rules for identifiers.

6. Temporary Tables

SQL Server supports both local and global temporary tables. A local temporary table exists only for the duration of a connection or a compound statement, while a global temporary table remains in the database permanently but the rows exist only within a given connection. When the connection is closed, the data in the global temporary table disappears.

7. STUFF Function vs REPLACE Function

The STUFF function is used to overwrite existing characters in a string, while the REPLACE function is used to replace existing characters with new characters. The syntax for the STUFF function is STUFF(string_expression, start, length, replacement_characters), and the syntax for the REPLACE function is REPLACE(string_expression, search_string, replacement_string).

8. Primary Key, Unique Key, Foreign Key

A primary key is a unique identifier for a row within a database table. It enforces entity integrity and ensures that each row is uniquely identified. A unique key constraint also enforces uniqueness of values in a set of columns. A foreign key constraint prevents actions that would destroy links between tables with corresponding data values.

9. CHECK Constraint and NOT NULL Constraint

A CHECK constraint is used to limit the values that can be placed in a column, while a NOT NULL constraint enforces that the column will not accept null values. Both constraints are used to enforce domain integrity.

10. Scheduled Jobs

Scheduled jobs, also known as scheduled tasks, allow users to automate processes that run on regular or predictable cycles. SQL Server Agent provides a scheduling engine that allows users to schedule administrative tasks, such as database backups or updates, to run during times of slow business activity.

11. Advantages of Stored Procedures

Stored procedures offer several advantages, including reduced network traffic and latency, improved application performance, code reuse, encapsulation of logic, and better security for data.

12. Unindexed Tables

An unindexed table, also known as a heap, is a table that does not have a clustered index. The pages in a heap are not linked by pointers, but rather by Index Allocation Map (IAM) pages. Unindexed tables are useful for fast storing of data, especially when performing bulk inserts.

13. SQL Server Linked to Other Servers

SQL Server can be linked to other servers, such as Oracle, as long as there is an OLE-DB provider from Microsoft to allow the link. This allows for seamless integration and data exchange between different database systems.

14. BCP (Bulk Copy)

BCP is a tool used to copy a large amount of data from tables and views. It is particularly useful when you need to import a data file into a database table or view in a user-specified format. BULK INSERT command is another option for importing data into SQL Server.

These are just a few concepts and ideas related to SQL Server. Understanding these concepts will help you become more proficient in managing and working with SQL Server databases.