To store DLR information into a MySQL database you may use the dlr-storage = mysql configuration directive in the core group.In addition to that you must have a dlr-db group defined that specifies the table field names that are used to the DLR attributes and a mysql-connection group that defines the connection to the MySQL server itself.
Here is the example configuration
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group = core
.........
dlr-storage = mysql
group = mysql-connection
id = mydlr
host = localhost
username = foo
password = bar
database = dlr
max-connections = 1
group = dlr-db
id = mydlr
table = dlr
field-smsc = smsc
field-timestamp = ts
field-destination = destination
field-source = source
field-service = service
field-url = url
field-mask = mask
field-status = status
field-boxc-id = boxc