How to Delete Rows from a Table Based on Matching IDs Using SQL JOINs?

Delete Rows in a Table Based on Matching IDs Using JOIN

Delete operations in SQL can be used to remove specific rows from a table. In a scenario where you want to delete rows from a table based on matching IDs in another table, it's possible to utilize a JOIN operation to perform this task.

JOIN-Based Approach

The following query uses a JOIN operation to delete rows from table1 that have matching IDs in table2:

DELETE t1 
FROM Table1 t1
JOIN Table2 t2 ON t1.ID = t2.ID;

Explanation:

• The DELETE statement specifies that rows will be deleted from the table named 't1'.
• The JOIN clause links table1 ('t1') to table2 ('t2') based on the equality of their 'ID' columns.
• Rows in table1 that have matching IDs in table2 will be deleted.

Alternative Approach:

Alternatively, the same operation can be achieved using the following query:

DELETE FROM table1
WHERE ID IN (SELECT ID FROM table2);

This method uses a subquery to select the IDs from table2 and then uses the IN operator to match the IDs in table1. However, the JOIN-based approach is generally considered more efficient and easier to read.

Using Aliases

It's recommended to use table aliases (such as 't1' and 't2' in the JOIN query) to avoid confusion and prevent accidental deletion of all rows from table1 due to incomplete highlighting.

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