Why Does My SQL Query Show 'Unrecognized name: employees at [9:8]'?

Troubleshooting the SQL Error: "Unrecognized name: employees at [9:8]"

This error, "Unrecognized name: employees at [9:8]," typically arises in SQL queries due to an undefined table alias. Let's examine how this happens and how to fix it.

The problem surfaces when a table is referenced without a proper alias, particularly within the ON clause of a JOIN. Consider this example:

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

Notice that employees and departments are used in the ON clause, but haven't been formally defined as aliases before their use.

The Solution: Defining Table Aliases

The fix involves explicitly assigning aliases using the AS keyword:

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 AS employees and AS departments, we clearly define the aliases, resolving the ambiguity and eliminating the "Unrecognized name" error. This ensures the database understands which tables are being referenced in the ON clause.

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