ClickHouse/docs/en/query_language/functions/ext_dict_functions.md

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# Functions for working with external dictionaries {#ext_dict_functions}
For information on connecting and configuring external dictionaries, see [External dictionaries](../dicts/external_dicts.md).
## dictGetUInt8, dictGetUInt16, dictGetUInt32, dictGetUInt64
## dictGetInt8, dictGetInt16, dictGetInt32, dictGetInt64
## dictGetFloat32, dictGetFloat64
## dictGetDate, dictGetDateTime
## dictGetUUID
## dictGetString
`dictGetT('dict_name', 'attr_name', id)`
- Get the value of the attr_name attribute from the dict_name dictionary using the 'id' key.`dict_name` and `attr_name` are constant strings.`id`must be UInt64.
If there is no `id` key in the dictionary, it returns the default value specified in the dictionary description.
## dictGetTOrDefault {#ext_dict_functions_dictGetTOrDefault}
`dictGetTOrDefault('dict_name', 'attr_name', id, default)`
2018-03-25 02:04:22 +00:00
The same as the `dictGetT` functions, but the default value is taken from the function's last argument.
## dictIsIn
`dictIsIn ('dict_name', child_id, ancestor_id)`
- For the 'dict_name' hierarchical dictionary, finds out whether the 'child_id' key is located inside 'ancestor_id' (or matches 'ancestor_id'). Returns UInt8.
## dictGetHierarchy
`dictGetHierarchy('dict_name', id)`
- For the 'dict_name' hierarchical dictionary, returns an array of dictionary keys starting from 'id' and continuing along the chain of parent elements. Returns Array(UInt64).
## dictHas
`dictHas('dict_name', id)`
- Check whether the dictionary has the key. Returns a UInt8 value equal to 0 if there is no key and 1 if there is a key.
[Original article](https://clickhouse.yandex/docs/en/query_language/functions/ext_dict_functions/) <!--hide-->