```
SELECT version()
─version()─┐
│ 21.8.5.7  │
└───────────┘
```
We have a request, as a result of which we get an array.
When getting an item using a computed value, there is no value
```
SELECT
    arrayMap(x -> x, [[1], [2], [3]]) AS x,
    toTypeName(x),
    x[3 - 2] AS y,
    x[toInt64(1)] AS yy,
    x[toUInt8(1)] AS yyy

┌─x─────────────┬─toTypeName(arrayMap(lambda(tuple(x), x), [[1], [2], [3]]))─┬─y──┬─yy─┬─yyy─┐
│ [[1],[2],[3]] │ Array(Array(UInt8))                                        │ [] │ [] │ [1] │
└───────────────┴────────────────────────────────────────────────────────────┴────┴────┴─────┘
```
However, when the array is explicitly specified, the value is present.
The types are the same.
```
SELECT
    [[1], [2], [3]] AS x,
    toTypeName(x),
    x[3 - 2] AS y,
    x[toInt64(1)] AS yy,
    x[toInt8(1)] AS yyy

┌─x─────────────┬─toTypeName([[1], [2], [3]])─┬─y───┬─yy──┬─yyy─┐
│ [[1],[2],[3]] │ Array(Array(UInt8))         │ [1] │ [1] │ [1] │
└───────────────┴─────────────────────────────┴─────┴─────┴─────┘
```


{
        Field index = (*arguments[1].column)[0];
        if (builder)
            builder.initSink(input_rows_count);
        if (index == 0u)
            throw Exception("Array indices are 1-based", ErrorCodes::ZERO_ARRAY_OR_TUPLE_INDEX);
        if (!((res = executeNumberConst<UInt8>(arguments, index, builder))
            || (res = executeNumberConst<UInt16>(arguments, index, builder))
            || (res = executeNumberConst<UInt32>(arguments, index, builder))
            || (res = executeNumberConst<UInt64>(arguments, index, builder))
            || (res = executeNumberConst<Int8>(arguments, index, builder))
            || (res = executeNumberConst<Int16>(arguments, index, builder))
            || (res = executeNumberConst<Int32>(arguments, index, builder))
            || (res = executeNumberConst<Int64>(arguments, index, builder))
            || (res = executeNumberConst<Float32>(arguments, index, builder))
            || (res = executeNumberConst<Float64>(arguments, index, builder))
            || (res = executeStringConst (arguments, index, builder))
            || (res = executeGenericConst (arguments, index, builder))))
        throw Exception("Illegal column " + arguments[0].column->getName()
            + " of first argument of function " + getName(),
            ErrorCodes::ILLEGAL_COLUMN);
    }
    return res;
}
REGISTER_FUNCTION(ArrayElement)
{
    factory.registerFunction<FunctionArrayElement>();
}
}