how to disable primary key for a field.

Hi Everyone,

Please guide me, how to drop primary key option of field ORDERNUMBER. without dropping the field. [uncheck primary key]

CREATE COLUMN TABLE "NEO_xxx"."Z_ORDERDETAILS" ("ORDERNUMBER" INTEGER CS_INT NOT NULL ,

  "PRODUCTCODE" NVARCHAR(15) NOT NULL ,

    "ORDERLINENUMBER" INTEGER CS_INT NOT NULL ) UNLOAD PRIORITY 5 AUTO MERGE ;

ALTER TABLE "NEO_xxxx"."Z_ORDERDETAILS" ADD PRIMARY KEY ("ORDERNUMBER");

ALTER TABLE "NEO_xxxx"."Z_ORDERDETAILS" ADD CONSTRAINT "ORDERDETAILS_FK1" FOREIGN KEY ( "PRODUCTCODE" ) REFERENCES "NEO_xxxx"."Z_PRODUCTS" ("PRODUCTCODE") ON UPDATE RESTRICT ON DELETE CASCADE

ALTER TABLE "NEO_xxxxx"."Z_ORDERDETAILS" ADD CONSTRAINT "ORDERDETAILS_FK2" FOREIGN KEY ( "ORDERNUMBER" ) REFERENCES "NEO_xxxxxx"."Z_ORDERS" ("ORDERNUMBER") ON UPDATE RESTRICT ON DELETE CASCADE