Union

Function: UNION

The UNION function in Wonderful Relations allows you to combine the results of multiple queries into a single unified result set—similar to how SQL UNION works. This is particularly useful when you want to aggregate data from different sources with matching structure.

Each query included in the union must return the same number of columns, with matching data types and order. This requirement ensures compatibility when merging rows across different query blocks.

Purpose

Use UNION when you want to:

• Combine logically related but structurally separated datasets
• Reuse existing queries to construct composite views

Parameters

Each UNION entry contains the following parameters:

Query

The referenced query to be included in the union.

Sort Order

Defines the order in which the union queries are applied.

Condition (Optional)

If set, the union query is wrapped and a WHERE clause is applied directly to its result set.

Example: Basic UNION

Combining two queries (Query B and Query C) in Query A:

SELECT * FROM (
	QUERY_B
		UNION
	  QUERY_C
) QUERY_A

Example: UNION with Conditions

Each unioned query can also have its own condition:

SELECT * FROM (
  SELECT * FROM (QUERY_B) WHERE CONDITION_B
	  UNION
  SELECT * FROM (QUERY_C) WHERE CONDITION_C
) QUERY_A

Visual Example:

In Wonderful Relations, these conditions are defined in the union configuration and automatically applied during query execution.

Summary

✅ Combines multiple queries into one unified result set
✅ Supports individual filtering for each union component
✅ Preserves query reusability and modularity

The UNION function brings flexibility and composability to Wonderful Relations queries, empowering you to build powerful, multi-source views with ease.