Hi,
Version 4.1.3.20
Build MAIN-20.78
I'm trying to export only specific columns of a table. But it always exports all columns. Am I missing something?

The result is all columns with all constraints as you can see below.
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-- DDL for Table PURCHASE_INVOICE_HDR
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CREATE TABLE "PURCHASE_INVOICE_HDR" ("ID" NUMBER DEFAULT ON NULL "PURCHASE_INVOICE_PK"."NEXTVAL", "BP_ID" NUMBER, "DOCUMENT_DATE" DATE, "PAYMENT_TERM_ID" NUMBER, "GR_ID" NUMBER, "PO_ID" NUMBER, "STATUS" VARCHAR2(20), "PAYMENT_COMPLETE" NUMBER, "NOTES" VARCHAR2(200), "NET_AMOUNT" NUMBER, "DISCOUNT" NUMBER, "DISCOUNT_TYPE" NUMBER) ;
COMMENT ON COLUMN "PURCHASE_INVOICE_HDR"."PAYMENT_COMPLETE" IS 'YES/NO';
COMMENT ON COLUMN "PURCHASE_INVOICE_HDR"."DISCOUNT_TYPE" IS 'Currency or Percentage';
REM INSERTING into PURCHASE_INVOICE_HDR
SET DEFINE OFF;
Insert into PURCHASE_INVOICE_HDR (ID,DOCUMENT_DATE) values (385,to_date('20/04/19','DD/MM/RR'));
Insert into PURCHASE_INVOICE_HDR (ID,DOCUMENT_DATE) values (365,to_date('04/04/19','DD/MM/RR'));
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-- DDL for Index PURCHASE_INVOICE_PK
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CREATE UNIQUE INDEX "PURCHASE_INVOICE_PK" ON "PURCHASE_INVOICE_HDR" ("ID") ;
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-- Constraints for Table PURCHASE_INVOICE_HDR
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ALTER TABLE "PURCHASE_INVOICE_HDR" ADD CONSTRAINT "PURCHASE_INVOICE_PK" PRIMARY KEY ("ID") USING INDEX ENABLE;
ALTER TABLE "PURCHASE_INVOICE_HDR" MODIFY ("PAYMENT_COMPLETE" NOT NULL DISABLE);
ALTER TABLE "PURCHASE_INVOICE_HDR" MODIFY ("STATUS" NOT NULL ENABLE);
ALTER TABLE "PURCHASE_INVOICE_HDR" MODIFY ("PAYMENT_TERM_ID" NOT NULL ENABLE);
ALTER TABLE "PURCHASE_INVOICE_HDR" MODIFY ("DOCUMENT_DATE" NOT NULL ENABLE);
ALTER TABLE "PURCHASE_INVOICE_HDR" MODIFY ("BP_ID" NOT NULL ENABLE);
ALTER TABLE "PURCHASE_INVOICE_HDR" MODIFY ("ID" NOT NULL ENABLE);
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-- Ref Constraints for Table PURCHASE_INVOICE_HDR
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ALTER TABLE "PURCHASE_INVOICE_HDR" ADD CONSTRAINT "PINVOICE_BPID_BP_ID_FK" FOREIGN KEY ("BP_ID") REFERENCES "BUSINESS_PARTNER" ("ID") ENABLE;
ALTER TABLE "PURCHASE_INVOICE_HDR" ADD CONSTRAINT "PINVOICE_GRID_GR_ID_FK" FOREIGN KEY ("GR_ID") REFERENCES "GOODS_RECEIPT" ("ID") ENABLE;
ALTER TABLE "PURCHASE_INVOICE_HDR" ADD CONSTRAINT "PINVOICE_PAYTRMID_PAYTRM_ID_FK" FOREIGN KEY ("PAYMENT_TERM_ID") REFERENCES "PAYMENT_TERM" ("ID") ENABLE;
ALTER TABLE "PURCHASE_INVOICE_HDR" ADD CONSTRAINT "PINVOICE_POID_PO_ID_FK" FOREIGN KEY ("PO_ID") REFERENCES "PURCHASE_ORDER" ("ID") ENABLE;