我想要返回名稱代碼

Question

我有3個表，我想加入它。

檢查此琴：http://sqlfiddle.com/#!2/20410/2

在列：乙級，特爾佳，夸爾塔，金塔和而不是數字天蛾 ...我需要在「materias」表中的名稱。 但我檢查所有的ID從同一張表「materias」

這可能嗎？有人能幫助我嗎？

Answer 1

你可以做，以兩種方式使用內部連接和使用子查詢。

使用內部連接：

SELECT 
h.id_classe, 
h.id_aula, 
s.serie, 
m1.materia as segunda, 
m2.materia as terca, 
m3.materia as quarta, 
m4.materia as quinta, 
m5.materia as sexta 
FROM horario_de_aulas h 
INNER JOIN materias as m1 on h.segunda = m1.id_materia 
INNER JOIN materias as m2 on h.terca = m2.id_materia 
INNER JOIN materias as m3 on h.quarta = m3.id_materia 
INNER JOIN materias as m4 on h.quinta = m4.id_materia 
INNER JOIN materias as m5 on h.sexta = m5.id_materia 
INNER JOIN series s ON h.classe = s.id_serie = 1 
LIMIT 4 

使用子查詢

SELECT 
h.id_classe, 
h.id_aula, 
s.serie, 
(select materia from materias where id_materia=h.segunda) as segunda, 
(select materia from materias where id_materia=h.terca) as terca, 
(select materia from materias where id_materia=h.quarta) as quarta, 
(select materia from materias where id_materia=h.quinta) as quinta, 
(select materia from materias where id_materia=h.sexta) as sexta 
FROM horario_de_aulas h 
INNER JOIN materias m 
INNER JOIN series s ON h.classe = s.id_serie = 1 
LIMIT 4 

Answer 2

嘗試以下查詢：

SELECT 
h.id_classe, 
h.id_aula, 
s.serie, 
m1.materia as segunda, 
m2.materia as terca, 
m3.materia as quarta, 
m4.materia as quinta, 
m5.materia as sexta 
FROM horario_de_aulas h 
INNER JOIN materias as m1 on h.segunda = m1.id_materia 
INNER JOIN materias as m2 on h.terca = m2.id_materia 
INNER JOIN materias as m3 on h.quarta = m3.id_materia 
INNER JOIN materias as m4 on h.quinta = m4.id_materia 
INNER JOIN materias as m5 on h.sexta = m5.id_materia 
INNER JOIN series s ON h.classe = s.id_serie = 1 
LIMIT 4