Question

How can I merge multiple queries with different schemas cleanly?
Merging datasets with inconsistent schemas is a common challenge in ETL workflows, especially with large volumes of data from various sources. This question focuses on techniques in Power Query to handle schema mismatches gracefully—ensuring clean merges, consistent outputs, and scalable data models.

Answer 1

In Power BI, to cleanly combine several queries with various schemas:

• Prior to merging, standardize data types and column names using Power Query.
• Apply Column Selection (Table.SelectColumns) to align fields across queries.
• To handle optional or missing columns, use dynamic column handling or Table.ColumnNames.
• Use "Append Queries" for union-type operations (like appending tables), and use Table to deal with missing columns.AddColumn and null defaults.
• These steps ensure schema consistency, reduce errors, and make your data model scalable—especially when merging data from evolving or varied sources.