缺少左括號，我找不到一個錯誤。有人能幫我嗎？

Question

CREATE TABLE PRESCRIPTION 
(
    prescription_no NUMBER (7), 
    CONSTRAINT prescription_no_pk PRIMARY KEY, 
    pr_patient_no VARCHAR2(6), 
    CONSTRAINT pr_patient_no_fk FOREIGN KEY(patient) REFERENCES (patient_no), 
    pr_drug_no NUMBER(5), 
    CONSTRAINT pr_drug_no_fk FOREIGN KEY (drug) REFERENCES (drug_no), 
    drug_start_date DATE, 
    units_per_day NUMBER(3,2), 
    drug_end_date DATE 
); 

Answer 1

試試下面的查詢我改變您的查詢：

CREATE TABLE PRESCRIPTION 
( 
    prescription_no NUMBER (7) CONSTRAINT prescription_no_pk PRIMARY KEY, 
    pr_patient_no VARCHAR2(6) CONSTRAINT pr_patient_no_fk FOREIGN KEY(patient) 
    REFERENCES (patient_no), 
    pr_drug_no NUMBER(5) CONSTRAINT pr_drug_no_fk FOREIGN KEY (drug) 
    REFERENCES (drug_no), 
    drug_start_date DATE, 
    units_per_day NUMBER(3,2), 
    drug_end_date DATE 
); 

Answer 2

外鍵約束的語法如下： FOREIGN KEY (<this table's column name>) REFERENCES <another table>(<another table's column name>)。 在您的例子，假設patient有以下模式：

CREATE TABLE patient (
    patient_no VARCHAR2(6), 
    primary key (patient_no) 
    ) 

你引用它，如下所示：

CREATE TABLE PRESCRIPTION (
    prescription_no NUMBER (7), 
    pr_patient_no VARCHAR2(6) , 
    CONSTRAINT prescription_no_pk PRIMARY KEY (prescription_no), 
    CONSTRAINT pr_patient_no_fk FOREIGN KEY (pr_patient_no) REFERENCES patient(patient_no) 
    ) 

等。