# Add or update map
> Supported in: Batch, Streaming
Updates a value by key in a map or adds new key value pair.
**Expression categories:** Map
## Declared arguments
* **Expression:** Expression to set as value for the key.
*Expression\*
* **Key:** Key to add or update.
*Expression\*
* **Map:** Map expression.
*Expression\>*
**Type variable bounds:** *K accepts AnyType\*\*V accepts AnyType*
**Output type:** *Map\*
## Examples
### Example 1: Base case
**Argument values:**
* **Expression:** 4
* **Key:** k
* **Map:** `map_col`
| map\_col | **Output** |
| ----- | ----- |
| {
a -> 1,
b -> 2,
} | {
a -> 1,
b -> 2,
k -> 4,
} |
***
### Example 2: Base case
**Argument values:**
* **Expression:** 4
* **Key:** k
* **Map:** `map_col`
| map\_col | **Output** |
| ----- | ----- |
| {
a -> 1,
b -> 2,
k -> 2,
} | {
a -> 1,
b -> 2,
k -> 4,
} |
| {
a -> 1,
b -> 2,
} | {
a -> 1,
b -> 2,
k -> 4,
} |
***
### Example 3: Base case
**Argument values:**
* **Expression:** 4
* **Key:** k
* **Map:** `map_col`
| map\_col | **Output** |
| ----- | ----- |
| {
a -> 1,
b -> 2,
k -> 2,
} | {
a -> 1,
b -> 2,
k -> 4,
} |
***
### Example 4: Null case (ANSI mode off)
**Argument values:**
* **Expression:** 4
* **Key:** *null*
* **Map:** `map_col`
| map\_col | **Output** |
| ----- | ----- |
| {
a -> 1,
} | {
a -> 1,
} |
***
### Example 5: Null case (ANSI mode on)
**Argument values:**
* **Expression:** 4
* **Key:** *null*
* **Map:** `map_col`
| map\_col | **Output** |
| ----- | ----- |
| {
a -> 1,
} | *null* |
***
### Example 6: Null case
**Argument values:**
* **Expression:** 4
* **Key:** k
* **Map:** `map_col`
| map\_col | **Output** |
| ----- | ----- |
| *null* | *null* |
***
### Example 7: Null case
**Argument values:**
* **Expression:** *null*
* **Key:** k
* **Map:** `map_col`
| map\_col | **Output** |
| ----- | ----- |
| {
a -> 1,
} | {
a -> 1,
k -> *null*,
} |
***