mysql常用命令汇总

# 在指定列后添加字段，并指定默认值

ALTER TABLE product2 ADD COLUMN LogicID VARCHAR(100) DEFAULT NULL COMMENT '逻辑ID' AFTER ID;

# 为已存在字段添加索引

ALTER TABLE product2 ADD INDEX IDX_LogicID ( `LogicID` );

# 将字符串 与 数字 拼接后，更新

set LogicID = concat('B',ID)

按周统计： select DATE_FORMAT(create_time,'%Y%u') weeks,count(caseid) count from tc_case group by weeks;
按天统计： select DATE_FORMAT(create_time,'%Y%m%d') days,count(caseid) count from tc_case group by days;
按月统计： select DATE_FORMAT(create_time,'%Y%m') months,count(caseid) count from tc_case group by months;