**Example 1: To add an item to a table** The following ``put-item`` example adds a new item to the *MusicCollection* table. :: aws dynamodb put-item \ --table-name MusicCollection \ --item file://item.json \ --return-consumed-capacity TOTAL \ --return-item-collection-metrics SIZE Contents of ``item.json``:: { "Artist": {"S": "No One You Know"}, "SongTitle": {"S": "Call Me Today"}, "AlbumTitle": {"S": "Greatest Hits"} } Output:: { "ConsumedCapacity": { "TableName": "MusicCollection", "CapacityUnits": 1.0 }, "ItemCollectionMetrics": { "ItemCollectionKey": { "Artist": { "S": "No One You Know" } }, "SizeEstimateRangeGB": [ 0.0, 1.0 ] } } For more information, see `Writing an Item <https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/WorkingWithItems.html#WorkingWithItems.WritingData>`__ in the *Amazon DynamoDB Developer Guide*. **Example 2: To conditionally overwrite an item in a table** The following ``put-item`` example overwrites an existing item in the ``MusicCollection`` table only if that existing item has an ``AlbumTitle`` attribute with a value of ``Greatest Hits``. The command returns the previous value of the item. :: aws dynamodb put-item \ --table-name MusicCollection \ --item file://item.json \ --condition-expression "#A = :A" \ --expression-attribute-names file://names.json \ --expression-attribute-values file://values.json \ --return-values ALL_OLD Contents of ``item.json``:: { "Artist": {"S": "No One You Know"}, "SongTitle": {"S": "Call Me Today"}, "AlbumTitle": {"S": "Somewhat Famous"} } Contents of ``names.json``:: { "#A": "AlbumTitle" } Contents of ``values.json``:: { ":A": {"S": "Greatest Hits"} } Output:: { "Attributes": { "AlbumTitle": { "S": "Greatest Hits" }, "Artist": { "S": "No One You Know" }, "SongTitle": { "S": "Call Me Today" } } } If the key already exists, you should see the following output:: A client error (ConditionalCheckFailedException) occurred when calling the PutItem operation: The conditional request failed. For more information, see `Writing an Item <https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/WorkingWithItems.html#WorkingWithItems.WritingData>`__ in the *Amazon DynamoDB Developer Guide*.