CMPB_ASGN_DB is a standard SAP Structure so does not store data like a database table does. It can be used to define the fields of other actual tables or to process "Posting Structure for Campaign Assignment" Information within sap ABAP programs. This is done by declaring abap internal tables, work areas or database tables based on this Structure. These can then be used to store and process the required data appropriately. i.e. DATA: wa_CMPB_ASGN_DB TYPE CMPB_ASGN_DB.
The CMPB_ASGN_DB table consists of various fields, each holding specific information or linking keys about Posting Structure for Campaign Assignment data available in SAP. These include MANDT (Client), VBELN (Sales and Distribution Document Number), POSNR (Item number of the SD document), CAMPAIGN (Generic project planning: GUID from external R/3 system)... See below for full list along with technical details, documentation, text table, check tables, foreign key relationships, conversion routines, relevant tcodes and example ABAP select code etc. .