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Medium severityquery

Power BI Refresh Error:
1248

What does this error mean?

A subquery used as a derived table in the FROM clause is missing a required alias.

Common causes

  • 1Subquery in FROM clause without an AS alias: `SELECT * FROM (SELECT id FROM t)`
  • 2Porting SQL from a database that does not require derived table aliases
  • 3Nested subqueries where an inner subquery is missing its alias

How to fix it

  1. 1Step 1: Add an alias to every derived table: `SELECT * FROM (SELECT id FROM t) AS subq;`
  2. 2Step 2: For nested subqueries, every level needs its own alias: `SELECT * FROM (SELECT * FROM (SELECT id FROM t) AS inner_q) AS outer_q;`
  3. 3Step 3: Refactor complex nested subqueries into CTEs using WITH clause (MySQL 8.0+) for readability: `WITH cte AS (SELECT id FROM t) SELECT * FROM cte;`

Frequently asked questions

Why does MySQL require aliases on derived tables?

MySQL uses the alias to identify the derived table in the rest of the query. Without an alias, MySQL cannot reference the subquery result set in the outer SELECT, WHERE, or JOIN clauses.

Do CTEs in MySQL 8.0 require aliases?

No — CTEs defined in a WITH clause are referenced by the CTE name, not a derived table alias. CTEs are often cleaner than nested subqueries: `WITH cte AS (...) SELECT * FROM cte;`

Can MetricSign detect when a query syntax error breaks an ADF pipeline?

Yes — MetricSign captures ADF pipeline failures from Script and Lookup activities and surfaces the MySQL error code in the incident detail.

Official documentation: https://dev.mysql.com/doc/mysql-errors/8.0/en/server-error-reference.html

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