Postgresql delete with inner join

Older PostgreSQL versions? Here's your solution.

For versions such as PostgreSQL 8.2.11, the USING clause might prove insufficient. The alternative here involves combining a subquery alongside the IN clause:

DELETE FROM target_table
WHERE target_table_id IN (
  SELECT target_table_id FROM target_table
  JOIN source_table ON target_table.matching_column = source_table.matching_column
);
// SQL's way of saying "I don't know who you are. I don't know what you want, but I will find you...and I will delete you".


This method targets record IDs for deletion within a subquery and subsequently implements these IDs within the DELETE command.

Syntax clarity: the answer is alias

Complex DELETE commands that revolve around multiple tables can benefit from table aliases serving as the source of readability and clarity:

DELETE FROM target_table t
USING source_table s
WHERE t.id = s.target_table_id;
// Be gone 't' – Gandalf probably, if he was a database admin.


In the above example, t and s are aliases for target_table and source_table, respectively. The WHERE clause then employs these aliases for the purpose of matching between the two tables over a common ID.

Encountering issues? Give these a shot.

Encountering errors with DELETE JOIN statements? Consider the following remedies:

• Compatibility Check: Ensure that the syntax you're employing is compatible with your version of PostgreSQL.
• Condition Reassessment: Ensure that the join conditions of the WHERE clause are properly articulated.
• Reach out: Consult PostgreSQL community forums for similar issues and their respective solutions.

Common pitfalls and how to address them

When working with DELETE statements, bear these points in mind:

1. For PostgreSQL versions previous to 9.1, do not use CTE for deletion (it won't listen anyway).
2. Always back up your data. Think of it as a time machine for when ‘delete’ goes 'I'll be back' on you.
3. Take time to test the DELETE statements in a controlled environment before actual implementation.

Precision in targeted deletes

To ensure accuracy in delete operations, remember to:

• Review join conditions: Double-check the WHERE clause to ensure that the deletion scope is exactly where you want it.
• Subqueries: Treat them as powerful tools aiding in the targeting of deletion records in interconnected datasets.
• Gospel of best practices: Stick around with established SQL patterns when working with internal joins and DELETE commands to minimize any unintended loss of data.

Multiple joins? Yes, you can!

When we're dealing with multiple join relations, commas serve as the bridge in the USING clause. Be sure of the correct columns to join, separated with commas:

DELETE FROM target_table t
USING source_table_one s1, source_table_two s2
WHERE t.column1 = s1.column1
AND t.column2 = s2.column2;
// SQL version of 'Two's company, three's a crowd'


We're addressing two separate source tables within the USING clause, allowing for a more complex delete operation accounting for multiple associations.