SQL0407N  Assignment of a NULL value to a NOT NULL column "TBSPACEID=2, TABLEID=50, COLNO=8" is not allowed.  SQLSTATE=23502 

上面的错误信息没有直接给出table名，可以通过下面的语句得到table和column

SELECT * FROM SYSCAT.TABLES WHERE TBSPACEID = 2 AND TABLEID = 50

SELECT * FROM SYSCAT.COLUMNS WHERE  TABNAME= '*******' AND COLNO = 8