使用Where子句比较两个表中的列

SELECT t1.column1, t2.column2
FROM table1 t1
INNER JOIN table2 t2 ON t1.common_column = t2.common_column
WHERE t1.some_condition = 'some_value';

SELECT t1.column1, t2.column2
FROM table1 t1
LEFT JOIN table2 t2 ON t1.common_column = t2.common_column
WHERE t2.some_condition IS NULL OR t2.some_condition = 'some_value';

SELECT t1.column1, t2.column2
FROM table1 t1
RIGHT JOIN table2 t2 ON t1.common_column = t2.common_column
WHERE t1.some_condition IS NULL OR t1.some_condition = 'some_value';

SELECT t1.column1, t2.column2
FROM table1 t1
FULL OUTER JOIN table2 t2 ON t1.common_column = t2.common_column
WHERE t1.some_condition IS NULL OR t2.some_condition IS NULL OR t1.some_condition = 'some_value';

SELECT e.employee_id, e.employee_name, d.department_name
FROM employees e
INNER JOIN departments d ON e.department_id = d.department_id
WHERE e.employee_status = 'active';