DB2 - meaning and definition. What is DB2
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What (who) is DB2 - definition

RELATIONAL MODEL DATABASE SERVER
Db2 Database; DB2; DB2 DWE; DATABASE 2; DB2/2; DB/2; Db2; IBM PureQuery; PureQuery; SQLCA; Ibm viper; IBM DB2 Express-C; Db/2; DB2 Everyplace; DB2 Express; IBM DB2; DB2 UDB; Db2 for Linux, UNIX and Windows; Db2 (Formerly Db2 for LUW); Db2 (formerly Db2 for LUW); Db2 for i; DB2/400; IBM Db2 Family

DB2         
DataBase 2 (Reference: IBM, DB)
DB2         
<database> A relational database from IBM. When running under IBM's MVS (Multiple Virtual Storage) operating system, DB2 is implemented on top of VSAM and uses its underlying data structures. DB2, later called "DB2 Universal DataBase", also runs under windows NT, AIX, Solaris and, most recently, Linux. [Details? Was there a "DB1"?] (1999-02-01)
DB2 SQL return codes         
SQLCODE; DB2 Codes; SQL Return Codes
SQL Return Codes are used on a day-to-day basis for the diagnosis of programming failures as a result of SQL calls by IBM Db2 programs. An important feature of IBM Db2 programs is the error processing.

Wikipedia

IBM Db2

Db2 is a family of data management products, including database servers, developed by IBM. It initially supported the relational model, but was extended to support object–relational features and non-relational structures like JSON and XML. The brand name was originally styled as DB/2, then DB2 until 2017 and finally changed to its present form.

Examples of use of DB2
1. Those titles include the DB2 database, Tivoli software for managing computer networks and Websphere middleware.
2. IBM‘s DB2 database software competes with Oracle‘s own, and the two routinely joust for the No 1 position.
3. BluePhoenix reported it would modernize the bank‘s mortgage loan application from a Unisys system to an IBM mainframe, and its database will be modernized to a DB2 database.