Which pattern safely updates a table based on a value computed by a subquery?

Problem Statement

Explanation

You can compute a value in a subquery and set the column in one statement. This keeps the change atomic and clear. Make sure the subquery is selective and indexed to avoid row by row scans in large tables.

Code Solution

SolutionRead Only

UPDATE orders o
SET discount = (
  SELECT CASE WHEN vip THEN 0.1 ELSE 0 END
  FROM customers c WHERE c.id = o.customer_id
);

Practice Sets

This question appears in the following practice sets:

Subqueries & CTEs (incl. Recursive)

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Which pattern safely updates a table based on a value computed by a subquery?

Problem Statement

Explanation

Code Solution

Practice Sets

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Master Interviews Anywhere, Anytime

Which pattern safely updates a table based on a value computed by a subquery?

Problem Statement

Explanation

Code Solution

Practice Sets

Related Questions

Which SQL statement retrieves all columns and rows from a table named employees?

Which clause filters rows before aggregation and affects which rows are grouped?

What is the default sort order when ORDER BY is used without ASC or DESC?

Which construct is commonly used to paginate results in SQL engines like Postgres and MySQL?

Which predicate correctly checks for missing values in standard SQL?

More from SQL & Databases

Master Interviews
Anywhere, Anytime