ADD expression for numeric increment in DynamoDB

Introduction

The ADD expression lets you increase or decrease a number in your database easily without replacing the whole item.

When you want to count how many times something happens, like page views.

When you need to add points to a user's score in a game.

When you want to update inventory counts after a sale.

When you want to track how many times a button is clicked.

When you want to increase a numeric value without reading it first.

Syntax

DynamoDB

UpdateExpression: "ADD attributeName :incrementValue"
ExpressionAttributeValues: { ":incrementValue": {"N": "number"} }

The ADD expression only works with numbers or sets in DynamoDB.

You provide the amount to add as a value with a colon prefix, like :incrementValue.

Examples

This adds 1 to the 'visits' attribute.

DynamoDB

UpdateExpression: "ADD visits :inc"
ExpressionAttributeValues: { ":inc": {"N": "1"} }

This adds 10 to the 'score' attribute.

DynamoDB

UpdateExpression: "ADD score :points"
ExpressionAttributeValues: { ":points": {"N": "10"} }

This subtracts 5 from the 'stock' attribute (using a negative number).

DynamoDB

UpdateExpression: "ADD stock :amount"
ExpressionAttributeValues: { ":amount": {"N": "-5"} }

Sample Program

This command adds 3 to the Quantity attribute of the product with ProductId '123'. It returns the new Quantity value.

DynamoDB

aws dynamodb update-item \
  --table-name Products \
  --key '{"ProductId": {"S": "123"}}' \
  --update-expression "ADD Quantity :inc" \
  --expression-attribute-values '{":inc": {"N": "3"}}' \
  --return-values UPDATED_NEW

Important Notes

If the attribute does not exist, ADD creates it with the value you provide.

You can use negative numbers to subtract values.

ADD works only with number or set types, not strings.

Summary

ADD expression updates numeric attributes by adding a value.

It can increase or decrease numbers without reading the current value first.

Useful for counters, scores, and inventory updates.