mysql自动填写当前时间

在navicat操作界面创建表时，如果需要自动填写时间，可以操作如下

CURRENT_TIMESTAMP

为表添加索引

ALTER table tableName ADD INDEX indexName(columnName)

追加外键

ALTER TABLE tb_commentPhoto ADD CONSTRAINT FK_comment_phone
FOREIGN KEY tb_goodsComment(id) REFERENCES tb_commentPhoto(comment_id);

mysql更新语句、新增列、删除列

# 更新
update user set name='张三' where id=111
# 删除
DELETE FROM table_name [WHERE Clause]

# 增加字段
alter table 表名 add column 列名 类型;
# 删除字段
alter table 表名 dropcolumn 列名 ;

联合更新

    # 联合更新
    update malluser set master_master_id=3 where master_id in (select a.id from (select id from  malluser where id like '15%')a)  

统计某字段重复数据

    # 统计某字段重复数据
    SELECT phone, COUNT(*) AS sumCount FROM malluser GROUP BY phone HAVING sumCount > 1;