Services or capabilities described in Amazon Web Services documentation might vary by Region. To see the differences applicable to the China Regions,
see Getting Started with Amazon Web Services in China
(PDF).
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"
}
}
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