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Tuesday, June 3, 2008

NULLS

     Testing for Null Values 
     How To Check If Any, ALL Or No Parameters Have A NULL Value 
     Return The First Non Null Value 
     Return Null If A Value Is A Certain Value 
     Concatenation with NULL values 
     NOT IN and NULLs

Dates

     How to find the first and last days in years, months etc 
     Epoch Date 
     Get Datetime Without Time 
     Date Ranges Without Loops 
     Calculate Birthday In Years 
     Formatting Dates 
     Calling Stored Procedures With Datetime Parameters 
     Trouble With ISDATE And Converting To SMALLDATETIME

Sorting, Limiting Ranking, Transposing and Pivoting

     Return Top N Rows 
     Dynamic TOP 
     Sorting Numbers Stored In A Varchar Column 
     Row To Column (PIVOT)
     Column To Row (UNPIVOT)
     Split A String By Using A Number Table 
     Concatenate Values From Multiple Rows Into One Column
     Concatenate Values From Multiple Rows Into One Column Ordered
     How To Use ROW_NUMBER() In A WHERE Clause
     Rank 
     Dense Rank 
     Row Number 
     Sort certain values last 
     Returning The Maximum Value For A Row

Handy tricks

     5 ways to return rows from one table not in another table 
     Order IP Addresses 
     Data formatting dates 
     Data formatting SSN 
     6 Different Ways To Get The Current Identity Value 
     Use XACT_ABORT to roll back non trapable error transactions 
     Random Sorting 
     Sort Values Ascending But NULLS Last 
     Adding Leading Zeros To Integer Values 
     How do I format money/decimal data with commas? 
     Find Out How Many Occurrences Of A Substring Are In A String 
     Ten SQL Server Functions That You Have Ignored Until Now 
     Use the *1 trick to do math with two varchar values 
     Store The Output Of A Stored Procedure In A Table Without Creating A Table 
     Find all The Rows Where Any Of The Columns Is Null Or Zero Or Both
     Three Ways To Display Two Counts From a Table Side By Side
     Finding duplicates across columns
     Use REPLACE To eliminate unwanted characters

Pitfalls

     Update triggers 
     Integer math 
     Identity Values And Triggers 
     Use XACT_STATE() To Check For Doomed Transactions 
     Three differences between COALESCE and ISNULL 
     Non deterministic functions and nullif 
     Subquery typo with using in 
     ISNUMERIC Trouble 
     Case Without Else 

 

Query Optimization

     Case Sensitive Search 
     No Functions on Left Side of Operator 
     Query Optimizations With Dates 
     Optimization: Set Nocount On
     No Math In Where Clause 
     Don't Use (select *), but List Columns

Undocumented but handy

     xp_getnetname 
     xp_fileexist 
     xp_dirtree 
     xp_subdirs 
     xp_getfiledetails 
     xp_fixeddrives 
     Sp_tempdbspace 
     xp_enumdsn 
     xp_enumerrorlogs 
     Some Undocumented DBCC Commands 
     sp_MSForEachtable
     sp_MSforeachDB

Usefull Admin stuff For The Developer

     sys.dm_exec_sessions
     Find all tables that contain a certain column
     Find All Tables Without Triggers In SQL Server
     Find all Primary and Foreign Keys In A Database
     Find Out If A Table Has An Identity Column
     Use the sys.dm_db_index_usage_stats dmv to check if indexes are being used