ORA-00904：无效的标识符

Question

我尝试使用Oracle数据库编写以下内部联接查询：

 SELECT Employee.EMPLID as EmpID, 
        Employee.FIRST_NAME AS Name,
        Team.DEPARTMENT_CODE AS TeamID, 
        Team.Department_Name AS teamname
 FROM PS_TBL_EMPLOYEE_DETAILS Employee
 INNER JOIN PS_TBL_DEPARTMENT_DETAILS Team 
 ON Team.DEPARTMENT_CODE = Employee.DEPTID

这给出了以下错误：

 INNER JOIN PS_TBL_DEPARTMENT_DETAILS Team ON Team.DEPARTMENT_CODE = Employee.DEPTID
                                              *
ERROR at line 4:
ORA-00904: "TEAM"."DEPARTMENT_CODE": invalid identifier

一个表的DDL为：

CREATE TABLE "HRMS"."PS_TBL_DEPARTMENT_DETAILS"
(
  "Company Code" VARCHAR2(255),
  "Company Name" VARCHAR2(255),
  "Sector_Code" VARCHAR2(255),
  "Sector_Name" VARCHAR2(255),
  "Business_Unit_Code" VARCHAR2(255),
  "Business_Unit_Name" VARCHAR2(255),
  "Department_Code" VARCHAR2(255),
  "Department_Name" VARCHAR2(255),
  "HR_ORG_ID" VARCHAR2(255),
  "HR_ORG_Name" VARCHAR2(255),
  "Cost_Center_Number" VARCHAR2(255),
  " " VARCHAR2(255)
)
SEGMENT CREATION IMMEDIATE PCTFREE 10 PCTUSED 40 INITRANS 1 MAXTRANS 255 NOCOMPRESS

Answer 1

您的问题是那些有害的双引号。

SQL> CREATE TABLE "APC"."PS_TBL_DEPARTMENT_DETAILS"
  2  (
  3    "Company Code" VARCHAR2(255),
  4    "Company Name" VARCHAR2(255),
  5    "Sector_Code" VARCHAR2(255),
  6    "Sector_Name" VARCHAR2(255),
  7    "Business_Unit_Code" VARCHAR2(255),
  8    "Business_Unit_Name" VARCHAR2(255),
  9    "Department_Code" VARCHAR2(255),
 10    "Department_Name" VARCHAR2(255),
 11    "HR_ORG_ID" VARCHAR2(255),
 12    "HR_ORG_Name" VARCHAR2(255),
 13    "Cost_Center_Number" VARCHAR2(255),
 14    " " VARCHAR2(255)
 15  )
 16  /

Table created.

SQL>

Oracle
SQL允许我们忽略数据库对象名称的大小写，只要我们创建它们时都使用大写的名称，或者不使用双引号即可。如果我们在脚本中使用大小写混合或小写并且将标识符括在双引号中，则当我们引用对象或其属性时，我们都被要求使用双引号和精确的大小写：

SQL> select count(*) from PS_TBL_DEPARTMENT_DETAILS
  2  where Department_Code = 'BAH'
  3  /
where Department_Code = 'BAH'
      *
ERROR at line 2:
ORA-00904: "DEPARTMENT_CODE": invalid identifier


SQL> select count(*) from PS_TBL_DEPARTMENT_DETAILS
  2  where "Department_Code" = 'BAH'
  3  /

  COUNT(*)
----------
         0

SQL>

tl; dr

不要在DDL脚本中使用双引号

（我知道大多数第三方代码生成器都可以，但是它们受过严格的训练，可以将所有对象名称都用大写字母表示。）

反之亦然。如果我们在不使用双引号的情况下创建表-

create table PS_TBL_DEPARTMENT_DETAILS
( company_code VARCHAR2(255),
  company_name VARCHAR2(255),
  Cost_Center_Number VARCHAR2(255))
;

在任何情况下，我们都可以引用它及其列：

select * from ps_tbl_department_details

或

select * from PS_TBL_DEPARTMENT_DETAILS;

或

select * from PS_Tbl_Department_Details
where COMAPNY_CODE = 'ORCL'
and cost_center_number = '0980'