记录下常用的mysql语句
1. 查询：select * from table where id = '1' order by id desc limit 0,20;
2. 更新：update table set name = ? where id = ?;
?????????????? PreparedStatement pstmts = conn.prepareStatement(sql);
?????????????? pstmts.setString(1, "xiaozhang");
?????????????? pstmts.setString(2, id);
?????????????? pstmts.executeUpdate();
3. 过滤查到的重复数据：select * from table where id = '1' group by name;
4. 2张表中根据关联字段合并一个临时表查询：select table1.name, table1.age, table2.num from table left join table2 on table1.name = table2.name where table1.name = 'xiaohua';
5. 插入新增数据：insert into table (name, age) values('xiaohua', '20');