统计内容中指定字符数量
SELECT SUM((LENGTH(`content`) - LENGTH(REPLACE(`content`,"出租", ""))) / LENGTH("出租")) AS sum FROM dr_1_news
总数去掉小数 / 四舍五入
SELECT ROUND(SUM((LENGTH(`content`) - LENGTH(REPLACE(`content`,"出租", ""))) / LENGTH("出租"))) AS sum FROM dr_1_news