The arguments must be constants and have types that have the smallest common type. At least one argument must be passed, because otherwise it isn't clear which type of array to create. That is, you can't use this function to create an empty array (to do that, use the 'emptyArray\*' function described above).
Returns an 'Array(T)' type result, where 'T' is the smallest common type out of the passed arguments.
Get the element with the index 'n' from the array 'arr'.'n' must be any integer type.
Indexes in an array begin from one.
Negative indexes are supported. In this case, it selects the corresponding element numbered from the end. For example, 'arr\[-1\]' is the last item in the array.
If the index falls outside of the bounds of an array, it returns some default value (0 for numbers, an empty string for strings, etc.).
## has(arr, elem)
Checks whether the 'arr' array has the 'elem' element.
Returns 0 if the the element is not in the array, or 1 if it is.
In this example, Reaches is the number of conversions (the strings received after applying ARRAY JOIN), and Hits is the number of pageviews (strings before ARRAY JOIN). In this particular case, you can get the same result in an easier way:
In this example, each goal ID has a calculation of the number of conversions (each element in the Goals nested data structure is a goal that was reached, which we refer to as a conversion) and the number of sessions. Without ARRAY JOIN, we would have counted the number of sessions as sum(Sign). But in this particular case, the rows were multiplied by the nested Goals structure, so in order to count each session one time after this, we apply a condition to the value of the arrayEnumerateUniq(Goals.ID) function.
The arrayEnumerateUniq function can take multiple arrays of the same size as arguments. In this case, uniqueness is considered for tuples of elements in the same positions in all the arrays.
-`single_value`– A single value. Only numbers can be added to an array with numbers, and only strings can be added to an array of strings. When adding numbers, ClickHouse automatically sets the `single_value` type for the data type of the array. For more information about the types of data in ClickHouse, see "[Data types](../../data_types/index.md#data_types)". Can be `NULL`. The function adds a `NULL` element to an array, and the type of array elements converts to `Nullable`.
-`single_value`– A single value. Only numbers can be added to an array with numbers, and only strings can be added to an array of strings. When adding numbers, ClickHouse automatically sets the `single_value` type for the data type of the array. For more information about the types of data in ClickHouse, see "[Data types](../../data_types/index.md#data_types)". Can be `NULL`. The function adds a `NULL` element to an array, and the type of array elements converts to `Nullable`.
- If `size` is less than the original size of the array, the array is truncated from the right.
- If `size` is larger than the initial size of the array, the array is extended to the right with `extender` values or default values for the data type of the array items.
-`extender` — Value for extending an array. Can be `NULL`.
-`offset`– Indent from the edge of the array. A positive value indicates an offset on the left, and a negative value is an indent on the right. Numbering of the array items begins with 1.
-`length` - The length of the required slice. If you specify a negative value, the function returns an open slice `[offset, array_length - length)`. If you omit the value, the function returns the slice `[offset, the_end_of_array]`.