Error: "Unrecognized name: employees at [9:8]"

When using table alias, you may encounter the "Unrecognized name: employees at [9:8]" error. Let's analyze the reasons and provide the right solution.

Error analysis:

In the provided SQL query:

SELECT 
    employees.name AS employee_name,
    employees.role AS employee_role,
    departments.name AS department_name
FROM 
    `strange-calling-318804.employee_data.Employees`
    JOIN 
    `strange-calling-318804.employee_data.departments` 
    ON employees.department_id = departments.department_id

employees and departments alias are used in the ON clause:

ON employees.department_id = departments.department_id

However, the Employees and departments tables do not have explicitly defined alias in the FROM clause. This leads to an error because BigQuery requires that they must be defined before using aliases.

Solution:

To resolve this error, they must be defined before using the alias:

SELECT 
    employees.name AS employee_name,
    employees.role AS employee_role,
    departments.name AS department_name
FROM 
    `strange-calling-318804.employee_data.Employees` AS employees
    JOIN 
    `strange-calling-318804.employee_data.departments` AS departments 
    ON employees.department_id = departments.department_id

By adding aliases AS employees and AS departments] after the full table reference, the query now correctly recognizes the table and executes without errors.