Question

我有2个表，Facilities和Services。

CREATE TABLE Facilities (
facility_id NUMBER(2) NOT NULL,
facility_name VARCHAR2(20) NOT NULL,
CONSTRAINT pk_facil_id PRIMARY KEY (facility_id)
);

CREATE TABLE Services (
service_id NUMBER(2) NOT NULL,
service_name VARCHAR(20) NOT NULL,
service_facility NUMBER(2) NOT NULL,
CONSTRAINT pk_serviceid PRIMARY KEY (service_id)
);

ALTER TABLE Services
add CONSTRAINT fk_servicefacility FOREIGN KEY(service_facility) 
REFERENCES Facilities(facility_id);

如果我尝试将记录输入“服务”表，如下所示：

INSERT INTO Services (service_id, service_name, service_facility) 
SELECT 06, 'Rooms', 
(SELECT facility_id, FROM Facilities WHERE facility_name = 'Hotel') 
FROM Dual;

我在7个插入语句中有3个出现错误“缺少表达式”。缺少什么表达？

Answer 1

您发布的SQL语句有一个额外的逗号。如果在SQL * Plus中运行该语句，它将抛出ORA-00936：缺少表达式并准确显示错误发生的位置

SQL> ed
Wrote file afiedt.buf

  1  INSERT INTO Services (service_id, service_name, service_facility)
  2  SELECT 06, 'Rooms',
  3  (SELECT facility_id, FROM Facilities WHERE facility_name = 'Boston')
  4* FROM Dual
SQL> /
(SELECT facility_id, FROM Facilities WHERE facility_name = 'Boston')
                     *
ERROR at line 3:
ORA-00936: missing expression

如果删除逗号，则该语句有效

SQL> ed
Wrote file afiedt.buf

  1  INSERT INTO Services (service_id, service_name, service_facility)
  2  SELECT 06, 'Rooms',
  3  (SELECT facility_id FROM Facilities WHERE facility_name = 'Boston')
  4* FROM Dual
SQL> /

1 row created.

但请注意，我通常更喜欢Stefan的语法，您从Facilities中选择，而不是从带有标量子查询的dual中选择。

Answer 2

您的插入声明应为：

INSERT INTO 
    Services 
    (
        service_id, 
        service_name, 
        service_facility
    ) 
SELECT 
    06, 
    'Rooms', 
    facility_id 
FROM 
    Facilities 
WHERE 
    facility_name = 'Hotel'

在它的当前状态下，我提供的查询将为每个设施的房间添加一个服务记录，名称为Hotel。

然后在“双”表中添加连接，以便获得正确数量的插入/获得正确的设施。

语法错误：缺少表达式（ORA-00936）

2 个答案: