如何获得的行数与条件

Question

我有一个表像这样

id student teacher 
10  a  b 
11  c  b 
12  d  c 
13  e  b 

学生的“e”是3TH学生，其导师为“B”。 如何使用一个查询来获取此信息？

Answer 1

你可以那样做：

SELECT * FROM (
    SELECT @row := @row + 1 as row, t.* FROM student_table t, (SELECT @row := 0) r where t.teacher ='b' 
) s where student = 'e' 

Answer 2

非常接近于Secator

SELECT * 
FROM (
    SELECT (@row := @row + 1) AS rank, student 
    FROM my_table, 
    (SELECT @row := 0) q 
    WHERE teacher = 'b' 
) s 
WHERE student = 'e'