# ZADD

> Add a member to a sorted set, or update its score if it already exists.

## Arguments 

<ParamField body="key" type="str" required>
  The key of the sorted set.
</ParamField>
<ParamField body="scores" type="Dict[str, float]" required>
  A dictionary of elements and their scores.
</ParamField>

<ParamField body="xx" type="bool">
    Only update elements that already exist. Never add elements.
</ParamField>
<ParamField body="nx" type="bool">
    Only add new elements. Never update elements.
</ParamField>
<ParamField body="gt" type="bool">
    Update scores if the new score is greater than the old score.
</ParamField>
<ParamField body="lt" type="bool">
    Update scores if the new score is less than the old score.
</ParamField>
<ParamField body="ch" type="bool">
    Return the number of elements changed instead.
</ParamField>
<ParamField body="incr" type="bool">
    When this option is specified `ZADD` acts like `ZINCRBY`. Only one score-element pair can be specified in this mode.
</ParamField>

## Response

<ResponseField type="int"  required>
    The number of elements added to the sorted sets, not including elements already existing for which the score was updated.

    If `ch` was specified, the number of elements that were updated.

    If `incr` was specified, the new score of `member`.
</ResponseField>

<RequestExample>
```py Simple
# Add three elements
assert redis.zadd("myset", {
    "one": 1,
    "two": 2,
    "three": 3
}) == 3

# No element is added since "one" and "two" already exist
assert redis.zadd("myset", {
    "one": 1,
    "two": 2
}, nx=True) == 0

# New element is not added since it does not exist
assert redis.zadd("myset", {
    "new-element": 1
}, xx=True) == 0

# Only "three" is updated since new score was greater
assert redis.zadd("myset", {
    "three": 10, "two": 0
}, gt=True) == 1

# Only "three" is updated since new score was greater
assert redis.zadd("myset", {
    "three": 10,
    "two": 0
}, gt=True) == 1
```
</RequestExample>