> For the complete documentation index, see [llms.txt](https://docs.e6data.com/ingestion-engine/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.e6data.com/ingestion-engine/sql/functions/struct.md).

# Struct

*The e6 Ingestion Engine scalar functions are based on* [*Apache DataFusion*](https://arrow.apache.org/datafusion/) *and these docs are derived from the DataFusion function reference.*

## Quick reference

| Function              | Description     | Example              | Result                 |
| --------------------- | --------------- | -------------------- | ---------------------- |
| `struct(e1, e2, ...)` | Create a struct | `struct(1, 'hello')` | `{c0: 1, c1: 'hello'}` |

## `struct`

Returns an Arrow struct using the specified input expressions. Fields in the returned struct use the `cN` naming convention. For example: `c0`, `c1`, `c2`, etc.

```
struct(expression1[, ..., expression_n])
```

For example, this query converts two columns `a` and `b` to a single column with a struct type of fields `c0` and `c1`:

```sql
select * from t;
+---+---+
| a | b |
+---+---+
| 1 | 2 |
| 3 | 4 |
+---+---+

select struct(a, b) from t;
+-----------------+
| struct(t.a,t.b) |
+-----------------+
| {c0: 1, c1: 2}  |
| {c0: 3, c1: 4}  |
+-----------------+
```

#### Arguments

* **expression\_n**: Expression to include in the output struct. Can be a constant, column, or function, and any combination of arithmetic or string operators.


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