ClickHouse/docs/en/functions/ext_dict_functions.md

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<a name="ext_dict_functions"></a>
# Functions for working with external dictionaries
For information on connecting and configuring external dictionaries, see "[External dictionaries](../dicts/external_dicts.md#dicts-external_dicts)".
## 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
`dictGetT('dict_name', 'attr_name', id, default)`
Similar to the functions dictGetT, but the default value is taken from the last argument of the function.
## 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.