牛客MySQL-1.18UNION操作符
待解决:
SELECT country, name FROM Websites
WHERE country='CN'
UNION ALL
SELECT country, app_name FROM apps
WHERE country='CN'
ORDER BY country;
中如果select的时候不选择coutry但是想where针对country筛选可以吗？结果可以只有一列吗？
SELECT country, name FROM Websites
WHERE country='CN'
UNION ALL
SELECT country, app_name FROM apps
WHERE country='CN'
ORDER BY country;
中如果select的时候不选择coutry但是想where针对country筛选可以吗？结果可以只有一列吗？
