sql 中 limit 与 limit，offset连用的区别

limit与offset是mysql数据库使用的。
① select * from table limit 2,1;

//含义是跳过2条取出1条数据，limit后面是从第2条开始读，读取1条信息，即读取第3条数据

② select * from table limit 2 offset 1;

//含义是从第1条（不包括）数据开始取出2条数据，limit后面跟的是2条数据，offset后面是跳过第1条开始读取，即读取第2,3条

下面结合一道题目谈使用

Write a SQL query to get the second highest salary from the Employee table.

+----+--------+
| Id | Salary |
+----+--------+
| 1  | 100    |
| 2  | 200    |
| 3  | 300    |
+----+--------+

For example, given the above Employee table, the query should return 200 as the second highest salary. If there is no second highest salary, then the query should return null.

+---------------------+
| SecondHighestSalary |
+---------------------+
| 200                 |
+---------------------+

解答：

select (
  select distinct Salary from Employee order by Salary Desc limit 1 offset 1
)as SecondHighestSalary