# system.columns

Read-only metadata for columns across registered server databases. Use it to discover a table's declared schema rather than inferring a schema from its current values.

## Columns

| Name                 | Meaning                                                          |
| -------------------- | ---------------------------------------------------------------- |
| database             | Managed database name.                                           |
| table                | Table or view name; quote this identifier in SQL.                |
| name                 | Column name.                                                     |
| type                 | Declared type text.                                              |
| position             | One-based column position.                                       |
| default_kind         | Kind of declared default or generated value.                     |
| default_expression   | SQL expression defining that value.                              |
| is_in_primary_key    | Whether the column is part of the primary key.                   |
| is_nullable          | Whether the column permits a top-level NULL.                     |
| primary_key_position | Position in the declared key, or zero when absent.               |
| schema_name          | Connection namespace, such as main or temp.                      |
| is_temporary         | Whether the object belongs to the observing temporary namespace. |

## Example

```sql
CREATE TABLE documented_columns(id UInt32, label String);
```

```sql
SELECT name, type, position
FROM system.columns
WHERE "table" = 'documented_columns' AND schema_name = 'main'
ORDER BY position
FORMAT csv;
```

```text
"id","UInt32",1
"label","String",2
```

Always use the system qualifier. This service relation is provided by the server, rather than a standalone embedded connection. See [system.tables](https://coordinatordb.com/docs/reference/system-tables/tables) for object-level metadata.