IT18380: DB2 MAY RETURN INCORRECT RESULTS IF USING A CASE STATEMENT TO COMPARE FIXED CHAR/GRAPHIC STRINGS IN VARCHAR2 COMPATIBILITY MODE

DB2 Version 10.1 Fix Pack 6 for Linux, UNIX, and Windows

APAR status

• Closed as program error.

Error description

• When comparing fixed character or graphic strings where either
  side uses a CASE statement, DB2 may return incorrect results in
  VARCHAR2 compatibility mode.
  
  Example:
  
  CREATE TABLE T(C1 CHAR(4))
  INSERT INTO T VALUES ('M')
  SELECT * FROM T WHERE C1 = CASE WHEN 1=1 THEN 'M' END
  
  Incorrect Result:
  
  C1
  ----
  
    0 record(s) selected.
  

Local fix

• From the example above, cast the CASE statement to a fixed
  character string of the desired length:
  
  SELECT * FROM T WHERE C1 = CAST((CASE WHEN 1=1 THEN 'M' END) AS
  CHAR(1))
  
  C1
  --------
  M
  
    1 record(s) selected.
  

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * ALL                                                          *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * See Error Description                                        *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Upgrade to DB2 10.1 Fix Pack 6                               *
  ****************************************************************
  

Problem conclusion

• First fixed in DB2 10.1 Fix Pack 6
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

  IT18343

• APAR is sysrouted TO one or more of the following:

Fix information

• Fixed component name

  DB2 FOR LUW

• Fixed component ID

  DB2FORLUW

Applicable component levels

• RA10 PSN UP

     FIX