Sort
`select * from demo1 order by field asc, field desc;
Description:
asc ascending, desc descending
The default is asc
limit paging
select * from demo2 limit 偏移量，几行数据
Description:
offset: indicates the offset, in general, how many lines are skipped, offset can be omitted, the default is 0, which means skip 0 lines; range: [0, + ∞)
count: start to fetch data after skipping the offset line, take count line records; range: [0, + ∞).
The values of offset and count in limit cannot be expressed by expressions.