Getting started with Microsoft SQL Server OVER Clause PIVOT / UNPIVOT Database Snapshots Retrieve information about the database The STUFF Function FOR XML PATH Cursors Join Common Table Expressions Move and copy data around tables Dates Limit Result Set Retrieve Information about your Instance With Ties Option Variables JSON in Sql Server Window functions Partitioning Stored Procedures GROUP BY Generating a range of dates COALESCE Split String function in Sql Server INSERT INTO CREATE VIEW String Functions Resource Governor ORDER BY WHILE loop System database - TempDb Migration Primary Keys MERGE Full-Text Indexing FOR JSON SELECT statement DBMAIL Index Queries with JSON data Storing JSON in SQL tables OPENJSON Ranking Functions Trigger Converting data types NULLs Transaction isolation levels Advanced options IF...ELSE TRY/CATCH Data Types User Defined Table Types Table Valued Parameters In-Memory OLTP (Hekaton)Temporal Tables Insert Sequences SCOPE_IDENTITY()Views Use of TEMP Table Scheduled Task or Job Isolation levels and locking Sorting/ordering rows Privileges or Permissions Foreign Keys SQLCMD File Group cross apply Basic DDL Operations in MS SQL Server Computed Columns UNION Subqueries Last Inserted Identity CLUSTERED COLUMNSTORE Parsename Installing SQL Server on Windows Aggregate Functions Querying results by page Schemas Backup and Restore Database Transaction handling Natively compiled modules (Hekaton)Database permissions Spatial Data Dynamic SQL Pagination Query Hints Modify JSON text Row-level security Dynamic data masking Export data in txt file by using SQLCMD Encryption Managing Azure SQL Database Common Language Runtime Integration Delimiting special characters and reserved words CASE Statement DBCC BULK Import Query Store Service broker Analyzing a Query Microsoft SQL Server Management Studio Shortcut Keys Permissions and Security PHANTOM read Filestream Drop Keyword String Aggregate functions in SQL Server SQL Server Evolution through different versions (2000 - 2016)SQL Server Management Studio (SSMS)Logical Functions Dynamic SQL Pivot Alias Names in Sql Server bcp (bulk copy program) Utility

Analyzing a Query

Scan vs Seek

When viewing an execution plan, you may see that SQL Server decided to do a Seek or a Scan.

A Seek occurs when SQL Server knows where it needs to go and only grab specific items. This typically occurs when good filters on put in a query, such as where name = 'Foo'.

A Scan is when SQL Server doesn't know exactly where all of the data it needs is, or decided that the Scan would be more efficient than a Seek if enough of the data is selected.

Seeks are typically faster since they are only grabbing a sub-section of the data, whereas Scans are selecting a majority of the data.

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