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我有一张表,其中包括以下字段: country, price and units 我试图用它SELECT COUNT(*)来获取每个国家/地区的总和,售出多少单位。 MySQL 的正确说法是什么?
country, price and units
SELECT COUNT(*)
SELECT country, SUM(units) FROM mytable GROUP BY country
我有一个未通过验证的对比度切换器。我已阅读脚本标记中何时需要 CDATA 部分? 并尝试转义字符并使用 CDATA 但我仍然收到两者的验证错