How Can I Efficiently Update MySQL Table Values from Another Table?

Efficiently Updating MySQL Table Values from Another

Problem Overview

The task is to update the tobeupdated table with data from the original table based on matching values stored in a VARCHAR(32) field. The current query, while functional, suffers from performance issues.

Solution

To enhance performance, consider the following optimized query:

UPDATE tobeupdated
INNER JOIN original ON (tobeupdated.value = original.value)
SET tobeupdated.id = original.id

This query leverages the JOIN syntax instead of multiple WHERE conditions, making it easier to read. Additionally, ensure that both tables have indexes created on the value field to facilitate faster lookups during the join operation.

Simplified Query

For further optimization, a simplified version of the query using the USING keyword is recommended:

UPDATE tobeupdated
INNER JOIN original USING (value)
SET tobeupdated.id = original.id

The USING keyword is employed when both tables in a join share an identical named key (such as id in this case), denoting an equi-join optimization.

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