此列列表沒有唯一鍵或主鍵？

Question

我已經為父表編寫了代碼，但是當我嘗試運行 sql 命令來生成子表時，我得到了一個匹配的錯誤：

“此列列表沒有匹配的唯一鍵或主鍵”

父表生成如下：

CREATE TABLE dabel3_RetailCenter 
(store_id CHAR (4) NOT NULL, 
store_type VARCHAR2 (15) NOT NULL, 
store_st_num CHAR (4) NOT NULL,
store_st_name VARCHAR2 (50) NOT NULL, 
store_city VARCHAR2 (15) NOT NULL, 
store_state VARCHAR2 (12) NOT NULL, store_ZIP CHAR (5),
CONSTRAINT dabel3_store_id_pk PRIMARY KEY (store_id));

CREATE TABLE dabel3_Trans_Type (
TM_ID CHAR (2) NOT NULL, 
TM_Type VARCHAR2 (15) NOT NULL, 
CONSTRAINT dabel3_Trans_type_TM_ID_pk PRIMARY KEY (TM_ID), 
CONSTRAINT TM_Type_UNQ UNIQUE (TM_TYPE));

CREATE TABLE dabel3_Trans_Mode (
TM_ID CHAR (2) NOT NULL, 
TM_Route VARCHAR2 (15) NOT NULL, 
TM_Sched_Num CHAR (3) NOT NULL,
CONSTRAINT dabel3_Trans_mode_pk PRIMARY KEY (TM_ID, TM_Sched_Num), 
CONSTRAINT dabel3_trans_mode_TM_ID_fk FOREIGN KEY (TM_ID) REFERENCES dabel3_Trans_Type (TM_ID));

但是，子表不會生成。 知道我做錯了什么嗎？

CREATE TABLE dabel3_Shipment (
pkg_track_num VARCHAR2 (15) NOT NULL, 
pkg_weight CHAR (7) NOT NULL, 
pkg_dimensions VARCHAR2 (20), 
pkg_insurance VARCHAR2 (50), 
pkg_dest_city VARCHAR2 (20) NOT NULL, 
pkg_dest_state CHAR (2) NOT NULL, 
pkg_dest_ZIP CHAR (5) NOT NULL, 
pkg_due_date DATE NOT NULL,
store_id CHAR (4) NOT NULL, 
TM_ID CHAR (2) NOT NULL, 
TM_Sched_Num CHAR (3) NOT NULL, 
CONSTRAINT dabel3_pkg_track_num_pk PRIMARY KEY (pkg_track_num), 
CONSTRAINT dabel3_shipment_store_id_fk FOREIGN KEY (store_id) REFERENCES dabel3_RetailCenter (store_id),
CONSTRAINT dabel3_shipment_TM_ID_fk FOREIGN KEY (TM_ID) REFERENCES dabel3_Trans_Type (TM_ID),
CONSTRAINT dabel3_shipment_TM_Sched_Num_fk FOREIGN KEY (TM_Sched_Num) REFERENCES dabel3_Trans_Mode (TM_Sched_Num));

Answer 1

如果我遇到這樣的問題，我會將失敗的語句分割成更容易調試的部分：

CREATE TABLE dabel3_Shipment (
  pkg_track_num VARCHAR2 (15) NOT NULL, 
  pkg_weight CHAR (7) NOT NULL, 
  pkg_dimensions VARCHAR2 (20), 
  pkg_insurance VARCHAR2 (50), 
  pkg_dest_city VARCHAR2 (20) NOT NULL, 
  pkg_dest_state CHAR (2) NOT NULL, 
  pkg_dest_ZIP CHAR (5) NOT NULL, 
  pkg_due_date DATE NOT NULL,
  store_id CHAR (4) NOT NULL, 
  TM_ID CHAR (2) NOT NULL, 
  TM_Sched_Num CHAR (3) NOT NULL
);
Table DABEL3_SHIPMENT created

ALTER TABLE dabel3_Shipment ADD                       
  CONSTRAINT dabel3_pkg_track_num_pk PRIMARY KEY (pkg_track_num); 
Table DABEL3_SHIPMENT altered.

ALTER TABLE dabel3_Shipment ADD                                                     
  CONSTRAINT dabel3_shipment_store_id_fk FOREIGN KEY (store_id) 
  REFERENCES dabel3_RetailCenter (store_id);
Table DABEL3_SHIPMENT altered.

ALTER TABLE dabel3_Shipment ADD                                                     
  CONSTRAINT dabel3_shipment_TM_ID_fk FOREIGN KEY (TM_ID) 
  REFERENCES dabel3_Trans_Type (TM_ID);
Table DABEL3_SHIPMENT altered.

ALTER TABLE dabel3_Shipment ADD                                                     
  CONSTRAINT dabel3_sht_TM_Sched_Num_fk 
  FOREIGN KEY (TM_Sched_Num) 
  REFERENCES dabel3_Trans_Mode (TM_Sched_Num);
ORA-02270: no matching unique or primary key for this column

所以，錯誤就在這個子句中。 引用的列上沒有主鍵或唯一鍵。 一旦我們修復它...

ALTER TABLE dabel3_Trans_Mode ADD 
  CONSTRAINT dabel3_Trans_mode_sm_unq UNIQUE(TM_Sched_Num);
Table DABEL3_TRANS_MODE altered.

...約束編譯：

ALTER TABLE dabel3_Shipment ADD                                                     
  CONSTRAINT dabel3_sht_TM_Sched_Num_fk 
  FOREIGN KEY (TM_Sched_Num) 
  REFERENCES dabel3_Trans_Mode (TM_Sched_Num);
Table DABEL3_SHIPMENT altered.

編輯：

@The Impaler 顯然是正確的，復合鍵將是一個更好的解決方案。

Answer 2

dabel3_Shipment的最后一個表創建是錯誤的：

CONSTRAINT dabel3_shipment_TM_Sched_Num_fk 
FOREIGN KEY (TM_Sched_Num) 
REFERENCES dabel3_Trans_Mode (TM_Sched_Num) -- NOT a key

問題是dabel3_Trans_Mode的列TM_Sched_Num不是鍵。 為了建立外鍵，它必須指向遠程表中的一個鍵。

被引用的表有一個復合鍵(TM_ID, TM_Sched_Num) 。 您正在嘗試使用部分密鑰，而那不是密鑰。 整個使用它，兩列，問題就解決了。

例如，您可以這樣做：

CONSTRAINT dabel3_shipment_TM_Sched_Num_fk 
FOREIGN KEY (TM_ID, TM_Sched_Num) 
REFERENCES dabel3_Trans_Mode (TM_ID, TM_Sched_Num)