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Writing Data To a Table

Relational database tables contain rows of data. Rows are composed of columns.

DynamoDB tables contain items. Items are composed of attributes.

This section describes how to write one row (or item) to a table.

SQL

A table in a relational database is a two-dimensional data structure composed of rows and columns. Some database management systems also provide support for semi-structured data, usually with native JSON or XML data types. However, the implementation details vary among vendors.

In SQL, you use the INSERT statement to add a row to a table:

INSERT INTO Music 
    (Artist, SongTitle, AlbumTitle, 
    Year, Price, Genre, 
    Tags)
VALUES(
    'No One You Know', 'Call Me Today', 'Somewhat Famous',
    2015, 2.14, 'Country',
    '{"Composers": ["Smith", "Jones", "Davis"],"LengthInSeconds": 214}'
);

The primary key for this table consists of Artist and SongTitle. You must specify values for these columns.

Note

In this example, we are using the Tags column to store semi-structured data about the songs in the Music table. We have defined the Tags column as type TEXT, which can store up to 65535 characters in MySQL.

DynamoDB

In Amazon DynamoDB, you use the PutItem action to add an item to a table:

{
    TableName: "Music",
    Item: {
        "Artist":"No One You Know",
        "SongTitle":"Call Me Today",
        "AlbumTitle":"Somewhat Famous",
        "Year": 2015,
        "Price": 2.14,
        "Genre": "Country",
        "Tags": {
            "Composers": [
                  "Smith",
                  "Jones",
                  "Davis"
            ],
            "LengthInSeconds": 214
        }
    }
}

The primary key for this table consists of Artist and SongTitle. You must specify values for these attributes.

Here are some key things to know about this PutItem example:

• DynamoDB provides native support for documents, using JSON. This makes DynamoDB ideal for storing semi-structured data, such as Tags. You can also retrieve and manipulate data from within JSON documents.

• The Music table does not have any predefined attributes, other than the primary key (Artist and SongTitle).

• Most SQL databases are transaction-oriented. When you issue an INSERT statement, the data modifications are not permanent until you issue a COMMIT statement. With Amazon DynamoDB, the effects of a PutItem action are permanent when DynamoDB replies with an HTTP 200 status code (OK).

Note

For code samples using PutItem, see Getting Started with DynamoDB.

The following are some other PutItem examples.

{
    TableName: "Music",
    Item: {
        "Artist": "No One You Know",
        "SongTitle": "My Dog Spot",
        "AlbumTitle":"Hey Now",
        "Price": 1.98,
        "Genre": "Country",
        "CriticRating": 8.4
    }
}

{
    TableName: "Music",
    Item: {
        "Artist": "No One You Know",
        "SongTitle": "Somewhere Down The Road",
        "AlbumTitle":"Somewhat Famous",
        "Genre": "Country",
        "CriticRating": 8.4,
        "Year": 1984
    }
}

{
    TableName: "Music",
    Item: {
        "Artist": "The Acme Band",
        "SongTitle": "Still In Love",
        "AlbumTitle":"The Buck Starts Here",
        "Price": 2.47,
        "Genre": "Rock",
        "PromotionInfo": {
            "RadioStationsPlaying":[
                 "KHCR", "KBQX", "WTNR", "WJJH"
            ],
            "TourDates": {
                "Seattle": "20150625",
                "Cleveland": "20150630"
            },
            "Rotation": "Heavy"
        }
    }
}

{
    TableName: "Music",
    Item: {
        "Artist": "The Acme Band",
        "SongTitle": "Look Out, World",
        "AlbumTitle":"The Buck Starts Here",
        "Price": 0.99,
        "Genre": "Rock"
    }
}

Note

In addition to PutItem, Amazon DynamoDB supports a BatchWriteItem action for writing multiple items at the same time.