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Amazon SimpleDB
Developer Guide (API Version 2009-04-15)

Performing a Conditional Delete

Conditional delete enables you to delete an item or one or more attributes of an item if the existing value of an attribute matches a value that you specify. If value does not match or is not present, the insert or update is rejected with a 409 (MultiValuedAttribute, ConditionalCheckFailed ) or 404 (AttributeDoesNotExist) error code.

Note

Conditional deletes can only match single-valued attributes.

To perform a conditional delete, specify the expected name and expected value for a DeleteAttributes operation. If the specified attribute does not exist, Amazon SimpleDB performs the delete.

In the following example, Amazon SimpleDB deletes the JumboFez product from the MyDomain domain if the quantity of the product reaches zero.

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https://sdb.amazonaws.com/ ?Action=DeleteAttributes &DomainName=MyDomain &ItemName=JumboFez &Expected.1.Name=quantity &Expected.1.Value=0 &AWSAccessKeyId=[valid access key id] &SignatureVersion=2 &SignatureMethod=HmacSHA256 &Timestamp=2010-01-25T15%3A03%3A05-07%3A00 &Version=2009-04-15 &Signature=[valid signature]

If the condition is met, Amazon SimpleDB returns output similar to the following.

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<PutAttributesResponse> <ResponseMetadata> <RequestId>490206ce-8292-456c-a00f-61b335eb202b</RequestId> <BoxUsage>0.0000219907</BoxUsage> </ResponseMetadata> </PutAttributesResponse>