Scope of temporary tables in SQL Server

##Temp`), on the other hand, are the city slickers that are accessible across sessions. However, they too get evicted when the last active session concludes their tenancy.

Local Example:

CREATE TABLE #LocalTemp (ID INT);
-- Just like your secret diary, only you can view it


Global" Example":

CREATE TABLE ##GlobalTemp (ID INT);
-- Like a Facebook post, everyone can see it until you delete it


When concurrency strikes, local temporary tables serve as isolators, akin to how headphones keep you sane in a crowded coffee shop, keeping your #CaffeineIntake data separate from #HipsterHats sightings. For scenarios like mass data imports, consider sliding into the DMs with table variables or memory-optimized table variables for snazzier performance and cleaner resource use.

##tableName ): like the company bulletin board 📋

• Everyone can see the notice (visible to all sessions).
• Erased clean at the end of the day (last referencing session ends).

Table Variable ( @tableName ): like your Post-it notes 📝

• Only you can see them (scoped to your batch, stored procedure, or function).
• Clean desk policy applies and they're binned at the day's end.

**Scope and Visibility**:

```markdown
Local 🔒 | Session Only
Global 🌐 | All Sessions
Table Variable 🔏 | Within your SP/batch/function

In essence — knowing the scope is as important as knowing how to code! 🌟

Wrangling the Temporary Tables

Crafting unique sessions

Craftiness comes in handy when data importing comes calling. If you wouldn't want clones of yourself, why let your temporary tables be identical twins?

Example:

DECLARE @tableName NVARCHAR(128) = '#Import_' + REPLACE(CONVERT(NVARCHAR(19), GETDATE(), 120), ':', '_') + '_' + CONVERT(NVARCHAR(10), @@SPID);
EXEC('CREATE TABLE ' + @tableName + ' (ID INT)');
-- Creates a unique temporary table, forever alone


Banishing existing temporary tables

As programmers, command is our right. Before creating a temporary table, especially when playing God, use OBJECT_ID to check its existence:

IF OBJECT_ID('tempdb..#LocalTemp') IS NOT NULL
  DROP TABLE #LocalTemp;
CREATE TABLE #LocalTemp (ID INT);
-- It's like being the Time Stone wielding Dr. Strange of SQL


Party-isolating EXEC commands

EXEC commands are the real party people; every time you call one, a new session springs up, keep in mind, after the party, the session goes poof, and so does your local temporary table.

Tipping the scales: table variables vs. temporary tables

Table variables (@table) may lack some of the features of temporary tables, but they shine in their own right:

• Quick on their feet with less logging, they're like the Ted Lasso of memory.
• Apt for low-lock environments where more users need access.

Their kryptonite? Large datasets and ornate operations. Temporary tables swoop in, rescuing the day with their statistics and indexing options.