Best way to create a temp table with same columns and type as a permanent table

How to streamline the process?

Raising our productivity bar and leveraging SQL server capabilities, the SELECT INTO command can save us substantial time. PostgreSQL also offers a similar handy code:

/* Hey there PostgreSQL, you're not left behind! */
CREATE TEMP TABLE temp_table AS SELECT * FROM original_table LIMIT 0;


This creates a column-identical temporary table temp_table, empty of data, calling it the architectural twin for original_table.

Point to ponder: Limitations with primary keys

While this method is uncomplicated and effective, remember it does not replicate primary keys and constraints. So, you get the structure but not the regulatory complexities - essentially an architectural plan without the building codes.

Also, for PostgreSQL, the new temporary table will be within a session-specific schema, say 'pg_temp_3', providing a robust layer of isolation and data security.

Under the hood: What's not copied?

Your carbon-copy temp table doesn't carry everything from its permanent sibling. Column structures are cloned, but index properties and constraints aren't. Here's the typical missing list:

• Indexes: Without these, temp table queries may not be as optimized.
• Constraints: You don’t have a safety net against erroneous data insertion.
• Triggers: Automatic responses to change events are amiss.
• Row identities: You'll need to re-identify primary keys and unique IDs.

Code variants for different SQL flavors

Presenting, methods to create temp tables across different SQL flavors:

SQL Server

Ever friendly SQL Server allows on-the-fly creation of temp tables with SELECT INTO:

/* Copy-pasting, the DBA way! */
SELECT TOP 0 *
INTO #CoolTempTable
FROM OriginalStylishTable;


PostgreSQL

For the synonym-lovers at PostgreSQL, note this syntax adjustment:

/* PostgreSQL going "Can I copy your homework, but make it different?" */
CREATE TEMP TABLE cool_temp_table AS 
SELECT * 
FROM original_stylish_table 
LIMIT 0;


MySQL

MySQL uses a similar technique, with temp tables being session-based:

/* MySQL's version of a secret diary, visible to your session only */
CREATE TEMPORARY TABLE cool_temp_table AS 
SELECT * 
FROM original_stylish_table 
WHERE FALSE;


Handling outliers

Some days, you'll need your temp table to dress differently:

• Column Renaming: Use aliases in your SELECT statement for friendlier column names.
• Changing Data Types: Modify data types with CAST or CONVERT as needed.
• Row Identifiers: Add extra SELECT columns to mimic identity columns or unique identifiers.