求下面数据库的错误？？

COM.ibm.db2.jdbc.DB2Exception: [IBM][CLI Driver][DB2/LINUXIA64] SQL0530N The insert or update value of the FOREIGN KEY "DB2INST1.ITEM.ITEM_LIBB_FK" is not equal to any value of the parent key of the parent table. SQLSTATE=23503 at COM.ibm.db2.jdbc.app.SQLExceptionGenerator.throw_SQLException(SQLExceptionGenerator.java:273)

我看item表中没有这个ITEM_LIBB_FK字段，请问这是什么原因？？？
[b]问题补充：[/b]
ALTER TABLE "DB2INST1"."ITEM"
ADD CONSTRAINT "ITEM_LIBB_FK" FOREIGN KEY
("LIBRARY_TYPE")
REFERENCES "DB2INST1"."LIBB"
("TYPE_ID")
ON DELETE RESTRICT
ON UPDATE RESTRICT
ENFORCED
ENABLE QUERY OPTIMIZATION;

你想说什么呢？
ALTER TABLE "DB2INST1"."ITEM"
ADD CONSTRAINT "ITEM_LIBB_FK" FOREIGN KEY
("LIBRARY_TYPE")
REFERENCES "DB2INST1"."LIBB"
("TYPE_ID")
ON DELETE RESTRICT
ON UPDATE RESTRICT
ENFORCED
ENABLE QUERY OPTIMIZATION;
这一段就是添加一个外键约束呀
把LIBRARY_TYPE与TYPE_ID关联起来呀

你主表里面的外键字段的值和外键关联的表里主键值没有相匹配的

外键约束问题，楼上正解