> ## Documentation Index
> Fetch the complete documentation index at: https://docs.narrative.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Unsupported Type Errors

> Resolve errors when NQL queries use unsupported data types or operations

NQL validates data types during query parsing and execution. When a query includes unsupported types or incompatible type operations, the platform returns a 422 error with details about the type issue.

## GEOMETRY type not supported in SELECT

The GEOMETRY type cannot be used directly in SELECT statements. This error occurs when your query attempts to return a geometry column or the result of a geometry function.

### Error response

```json theme={null}
{
  "type": "https://www.narrative.io/knowledge-base/support-troubleshooting/nql/unsupported-type-error",
  "title": "Unsupported Type Error: Unsupported GEOMETRY Type",
  "status": 422,
  "detail": "The NQL query includes the unsupported GEOMETRY type. The request cannot be processed because the GEOMETRY type is not supported in the SELECT.",
  "instance": "/nql/run",
  "logId": "2cf8fef9-9dc2-4438-b6f9-e28c386e48cc"
}
```

### Cause

Geometry functions like `STCIRCLE()` return GEOMETRY types that cannot be serialized in query results. While you can use geometry functions in JOIN conditions and WHERE clauses, you cannot SELECT them directly.

### Solution

Remove the GEOMETRY column from your SELECT statement. Keep geometry operations only in JOIN or WHERE clauses.

**Before (causes error):**

```sql theme={null}
SELECT
  maid,
  STCIRCLE(longitude, latitude, 15) AS geofence  -- GEOMETRY in SELECT
FROM companydata.locations
```

**After (fixed):**

```sql theme={null}
SELECT
  maid,
  longitude,
  latitude
FROM companydata.locations
```

If you need to use geometry for filtering, keep it in the JOIN or WHERE clause:

```sql theme={null}
SELECT
  observations.maid,
  observations.event_timestamp,
  pois.name AS poi_name
FROM companydata.observations
INNER JOIN companydata.pois
  ON STIntersects(
    STSafePoint(observations.longitude, observations.latitude),
    STCIRCLE(pois.longitude, pois.latitude, 15)
  )
```

## String concatenation type mismatch

The `||` operator concatenates strings but requires compatible types on both sides. This error occurs when you try to concatenate incompatible types.

### Error response

```json theme={null}
{
  "type": "https://www.narrative.io/knowledge-base/support-troubleshooting/nql/unsupported-type-error",
  "title": "Unsupported Type Error: String Concatenation",
  "status": 422,
  "detail": "The NQL query encountered an unsupported type error when attempting to concatenate different types using the '||' operator. The '||' operator can only concatenate :string || :string or <EQUIVALENTTYPE> || <EQUIVALENTTYPE> and is not compatible with '<RECORDTYPE:PEEK_DEFAULT(VARCHAR TYPE, VARCHAR VALUE)> || <CHAR(1)>'.",
  "instance": "/nql/parse",
  "logId": "7798e641-5d5e-47d3-a884-f5271e788b6b"
}
```

### Cause

The `||` operator requires both operands to be strings (or equivalent string types). Common causes include:

* Concatenating a complex record type with a string
* Mixing incompatible character types
* Using structured fields that haven't been extracted to simple strings

### Solution

Extract string values from complex types before concatenation, or cast values to compatible string types.

**Before (causes error):**

```sql theme={null}
SELECT
  "hashedemail" || '-' || "mobileiduniqueidentifier" || '-' || "eventtimestamp" AS unique_key
FROM companydata.events
```

**After (fixed):**

If the fields are structured types with nested values, extract the string value first:

```sql theme={null}
SELECT
  "hashedemail"."value" || '-' || "mobileiduniqueidentifier"."value" || '-' || CAST("eventtimestamp" AS VARCHAR) AS unique_key
FROM companydata.events
```

<Tip>
  When concatenating timestamps or other non-string types, use `CAST(field AS VARCHAR)` to convert them to strings first.
</Tip>

## General tips for type errors

1. **Check the `detail` field** — It identifies the specific types that are incompatible
2. **Review structured fields** — Many fields in Narrative are record types with `.value` subfields
3. **Use explicit casts** — When in doubt, cast values to the expected type with `CAST(field AS type)`
4. **Check the instance** — `/nql/parse` errors occur during query validation; `/nql/run` errors occur during execution

## Related content

<CardGroup cols={2}>
  <Card title="NQL Data Types" icon="list-check" href="/nql/data-types">
    Reference for supported data types
  </Card>

  <Card title="NQL Functions" icon="code" href="/nql/functions/index">
    Reference for built-in functions including geometry operations
  </Card>

  <Card title="NQL Troubleshooting" icon="triangle-exclamation" href="/guides/nql/troubleshooting">
    Overview of common NQL errors
  </Card>

  <Card title="Rosetta Stone Attributes" icon="language" href="/reference/rosetta-stone/attribute-types">
    Understanding structured attribute types
  </Card>
</CardGroup>