mysql - 我想要返回名称而不是 id

Question

我有 3 张桌子，我想加入它。

检查这个小提琴：http ://sqlfiddle.com/#!2/20410/2

在列中： segunda、terca、quarta、quinta 和 sexta 而不是数字......我需要“materias”表中的名称。但我检查了同一张表“材料”中的所有 ID

那可能吗？有人可以帮助我吗？

Answer 1

You can do that in two ways using inner joins and using sub queries.

Using Inner Join:

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

Using Sub Query

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

尝试以下查询：

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