Index Scan retrieves all the rows from the table. Index Seek retrieves selective rows from the table.
SQL SERVER – Difference between DISTINCT and GROUP BY – Distinct vs Group By
What is the difference between DISTINCT and GROUP BY? They usually produce the same plan. Use GROUP BY for aggregates and DISTINCT to remove duplicates.
SQL SERVER – Fix : Error 8101 An explicit value for the identity column in table can only be specified when a column list is used and IDENTITY_INSERT is ON
Error 8101 means you gave a value for an identity column. What IDENTITY_INSERT does, why there are two different errors, and why TRY CATCH misses it.
SQL SERVER – Fix : Error 701 There is insufficient system memory to run this query
For Error 701, insufficient system memory, compare max server memory with min server memory, check the paging file size, and free caches with DBCC commands.
SQL SERVER – @@IDENTITY vs SCOPE_IDENTITY() vs IDENT_CURRENT – Retrieve Last Inserted Identity of Record
@@IDENTITY vs SCOPE_IDENTITY() vs IDENT_CURRENT: how each one returns the last identity value, and why a trigger can make @@IDENTITY give the wrong one.
SQL SERVER – Stored Procedure – Clean Cache and Clean Buffer
DBCC FREEPROCCACHE will invalidate all stored procedure plans that the optimizer has cached in memory. Let us learn how to clean cache.
SQL SERVER – Fix: Error Msg 128 The name is not permitted in this context. Only constants, expressions, or variables allowed here. Column names are not permitted.
Msg 128, The name is not permitted in this context, shows up when one column is used as the DEFAULT of another. Use only constants, expressions or variables.