Purpose
Joins 1 to 31 additional sources to the main table in sequence. Each subsequent input is matched against the result built so far. Suitable for reference data, tariffs, product attributes and matching actuals to plans.
Inputs and outputs
From 2 to 32 named inputs. out contains fields prefixed with aliases, such as a.Product and b.Category.
Parameters
| Parameter | Settings and values | Options and limits |
|---|---|---|
inputs | Named inputs, each receiving a separate connection. | Count: 2–32 |
decimal | The decimal separator for numeric values in the input data. | Options: ., ,Default: . |
nulls_equal | Allow NULL to match NULL in keys. Empty keys do not match by default. | Default: disabled |
Properties of each input
| Parameter | What it configures |
|---|---|
id / label | A stable port identifier and user-facing name. |
alias | A unique column prefix; also required for the first input. |
how | The join mode for every input after the first. |
keys | left/right pairs with a numeric flag; up to 32 pairs. |
cardinality | Expected key uniqueness for checking the data structure. |
Step-by-step configuration
- Use the main table as the first input with alias a. Give the reference table alias b.
- Choose inner/left/right/full for each subsequent input.
- Add key pairs: a left field with the alias of an already joined input and a right field from the current source.
- Select the expected uniqueness; many_to_one is usually appropriate for ordinary reference data.
- Check row counts, empty fields and potential row multiplication caused by duplicate keys.
Rules and diagnostics
- inner keeps only matches; left keeps all left rows; right keeps all right rows; full keeps all rows from both sides. The missing side is filled with NULL.
- many_to_one requires unique right keys; one_to_many requires unique left keys; one_to_one requires both; many_to_many allows duplicates on both sides. Violations cause JOIN_CARDINALITY.
- With multiple keys, every pair must match. Numeric mode is configured separately for each pair.
- Duplicates on both sides produce every matching combination and can greatly enlarge the result. The cell limit stops an excessively large result.
Configuration example
Join sales a, containing ProductCode and Value, to reference table b, containing Code and Category. Set how=left, key a.ProductCode=b.Code and cardinality=many_to_one. Sales without a reference match remain with b.Category=NULL.