即使在写入正确的表名之后，在 BigQuery 中的 JOIN 查询中也会出现无法识别的名称错误答案

【问题标题】：Getting an error of unrecognized name in JOIN query in BigQuery even after writing the correct table names即使在写入正确的表名之后，在 BigQuery 中的 JOIN 查询中也会出现无法识别的名称错误
【发布时间】：2022-06-15 22:01:13
【问题描述】：

表名称是“员工”和“部门”。 'ON' 后的最后一行显示无法识别的名称错误

SELECT 
  employees.name AS employee_name,
  employees.role AS employee_role,
  departments.name AS department
FROM
  `my-project-01-351918.employee_id.employees`
  INNER JOIN `my-project-01-351918.employee_id.departments` 
  ON employees.department_id = departments.department_id;

如何修复查询以获得 JOIN 结果？我使用的是 BigQuery Sandbox 版本，这是 JOIN 功能不起作用的原因吗？

【问题讨论】：

标签： sql google-bigquery inner-join nameerror

【解决方案1】：

如果您使用带有反引号（`）的引用的表名，并且想在ON 子句中引用它而不使用表别名，它应该在下面看起来很难看。

SELECT 
  employees.name AS employee_name,
  employees.role AS employee_role,
  departments.name AS department
FROM
  `my-project-01-351918.employee_id.employees`
  INNER JOIN `my-project-01-351918.employee_id.departments` 
  ON `my-project-01-351918.employee_id.employees`.department_id =
     `my-project-01-351918.employee_id.departments`.department_id;

没有表别名，

您可以编写如下查询。请注意，只有{project}.{dataset} 部分用反引号引用。此表单具有与表名相同的别名，您可以在ON 子句中使用它。

SELECT 
  employees.name AS employee_name,
  employees.role AS employee_role,
  departments.name AS department
FROM
  `my-project-01-351918.employee_id`.employees
  INNER JOIN `my-project-01-351918.employee_id`.departments
  ON employees.department_id = departments.department_id;

使用表别名，

您可以使用表的显式别名并在ON 子句中使用它。

SELECT 
  employees.name AS employee_name,
  employees.role AS employee_role,
  departments.name AS department
FROM
  `my-project-01-351918.employee_id.employees` AS employees
  INNER JOIN `my-project-01-351918.employee_id.departments` AS departments
  ON employees.department_id = departments.department_id;

【讨论】：