Usr21 (assign user name address key)

Table function:
Assign the user name address code, that is, match the user name with its personnel number and address number. This is a key table for searching other user information by user name. If a table contains the persnumber field, you can associate the table with the user login name.

Table Structure:

Field name	Key	Initial Value	Data Element	Data Type	Length	Decimal places	Short text
Mandt	X	X	Mandt	Clnt	3	0	Client
Bname	X	X	Xubname	Char	12	0	User name in user master record
Persnumber			Ad_persnum	Char	10	0	Person Number
Addrnumber			Ad_addrnum	Char	10	0	Addresss number
Kostl			Xukostl	Char	8	0	Cost center
Start_menu			Xustart	Char	30	0	Start Menu

Field description:
MandtIt's a client (Group). I don't know much about sap.
BnameIt is a user login account. In the USR * series tables, it is a primary key (or the first field of the primary key ).
PersnumberIs the personnel number. In the SAP system, all personnel, including system users, customer contacts, and Supplier contacts, will be assigned a person's number, the main table is ADRP (the primary key also contains the validity period and country). In the ADR * series tables, it is a part of the primary key (the primary key also contains the addrnumber field or validity period field ).
AddrnumberIs the address number. In the SAP system, all organizations, including internal enterprises, customers, and suppliers, will assign an address number, the primary table is ADRC (the primary key also contains the validity period and country) and is a part of the primary key in the ADR * series tables (in these tables, the address numbers and personnel numbers are many-to-many relationships ).
KostlIt is the cost center. This field is not used in our applications. Literally, every login user is regarded as a member of a certain cost center, probably related to the HR and Fi modules. For more information, contact me.
Start_menuIs the Start Menu, save a transaction code, this is better understanding, that is, the user automatically starts a region menu after logging on.

The kostl and start_menu fields are very strange here. It is estimated that sap is gradually developed. The previous table did not contain the two information. When adding this new table, to minimize previousProgramSo it is placed here.

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* The start_menu field has an explanation. when viewing the usr01 table, we see two old fields stcod and strtt, which are used to set the start transaction, it seems that sap has considered this problem early in the morning, but with the development of the application, the original fields are discarded and new fields are used.