正文
难度困难
SQL架构
Employee 表包含所有员工。Employee 表有三列：员工Id，公司名和薪水。
+-----+------------+--------+ |Id | Company | Salary | +-----+------------+--------+ |1 | A | 2341 | |2 | A | 341 | |3 | A | 15 | |4 | A | 15314 | |5 | A | 451 | |6 | A | 513 | |7 | B | 15 | |8 | B | 13 | |9 | B | 1154 | |10 | B | 1345 | |11 | B | 1221 | |12 | B | 234 | |13 | C | 2345 | |14 | C | 2645 | |15 | C | 2645 | |16 | C | 2652 | |17 | C | 65 | +-----+------------+--------+
请编写SQL查询来查找每个公司的薪水中位数。挑战点：你是否可以在不使用任何内置的SQL函数的情况下解决此问题。
+-----+------------+--------+ |Id | Company | Salary | +-----+------------+--------+ |5 | A | 451 | |6 | A | 513 | |12 | B | 234 | |9 | B | 1154 | |14 | C | 2645 | +-----+------------+--------+
