How to Efficiently Update Multiple Records Based on a Single Record Change in SQL?

Making Changes to Multiple Records Based on a Single Record Change with SQL

Your question involves updating multiple database records with a single query, specifically when the change is based on a single record modification. In your case, you want to adjust the order of items within a list based on the movement of a particular item.

There are a couple of ways to approach this using SQL. One method, which you mentioned, involves using multiple queries. First, select the relevant records, and then use programming code to modify the data and update the records. However, as you noted, this approach is not ideal due to its synchronous nature and potential for multiple queries.

Another SQL-based solution is to leverage the following statement:

<code class="sql">UPDATE my_table SET position = position * 10;</code>

This modifies the data in a way that facilitates easy record updates. To move an item up or down the list, you can update the position field for that item accordingly. For instance, to make Pears the second item, you would use:

<code class="sql">UPDATE my_table SET position = 15 WHERE listId=1 AND name = 'Pears';</code>

This assigns Pears a position 10 times greater than its previous value. However, if you continue making changes, gaps may appear between item positions. To prevent this, periodically execute the following query:

<code class="sql">UPDATE my_table SET position = position * 10;</code>

This will ensure that there are always 9 available positions between each item. By implementing these SQL statements, you can efficiently update multiple records with a single query, simplifying the process of reordering items in a list.

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