Differences between a relational (SQL) database and DynamoDB when deleting data from a table - Amazon DynamoDB
Deleting data from a table with SQLDeleting data from a table in DynamoDB

Differences between a relational (SQL) database and DynamoDB when deleting data from a table

In SQL, the DELETE statement removes one or more rows from a table. Amazon DynamoDB uses the DeleteItem operation to delete one item at a time.

Deleting data from a table with SQL

In SQL, you use the DELETE statement to delete one or more rows. The WHERE clause determines the rows that you want to modify. The following is an example.

DELETE FROM Music
WHERE Artist = 'The Acme Band' AND SongTitle = 'Look Out, World';

You can modify the WHERE clause to delete multiple rows. For example, you could delete all of the songs by a particular artist, as shown in the following example.

DELETE FROM Music WHERE Artist = 'The Acme Band'

Deleting data from a table in DynamoDB

In DynamoDB, you can use either the DynamoDB API or PartiQL (a SQL-compatible query language) to delete a single item. If you want to modify multiple items, you must use multiple operations.

DynamoDB API

With the DynamoDB API, you use the DeleteItem operation to delete data from a table, one item at a time. You must specify the item's primary key values.

{
    TableName: "Music",
    Key: {
        Artist: "The Acme Band",
        SongTitle: "Look Out, World"
    }
}
Note

In addition to DeleteItem, Amazon DynamoDB supports a BatchWriteItem operation for deleting multiple items at the same time.

DeleteItem supports conditional writes, where the operation succeeds only if a specific ConditionExpression evaluates to true. For example, the following DeleteItem operation deletes the item only if it has a RecordLabel attribute.

{
    TableName: "Music",
    Key: {
        Artist: "The Acme Band",
        SongTitle: "Look Out, World"
    },
   ConditionExpression: "attribute_exists(RecordLabel)"
}
PartiQL for DynamoDB

With PartiQL, you use the Delete statement through the ExecuteStatement operation to delete data from a table, one item at a time. You must specify the item's primary key values.

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

DELETE FROM Music
WHERE Artist = 'Acme Band' AND SongTitle = 'PartiQL Rocks'

You can also specify additional conditions for the operation. The following DELETE operation only deletes the item if it has more than 11 Awards.

DELETE FROM Music
WHERE Artist = 'Acme Band' AND SongTitle = 'PartiQL Rocks' AND Awards > 11
Note

For code examples using DELETE and ExecuteStatement, see PartiQL delete statements for DynamoDB.