在Mysql查詢中使用GROUP_CONCAT

Question

我在我的數據庫中有五個表與我一起工作。一切正常，直到我開始使用組concat從數據庫中選擇狀態。

這些都是我的表：

• main_jobs
• sub_jobs
• 類別
• 狀態
• state_job_relationship

我的表創建的片段

create table if not exists category (
    id int(3) not null auto_increment, 
    parent int(5) not null, 
    name varchar(255) not null, 
    description text, 
    slug varchar(255), 
    level int (3), 
    PRIMARY KEY (id, slug)); 

create table if not exists state (
     id int(4) not null auto_increment, 
     country_id int(11) not null, 
     name varchar(255) not null, 
     PRIMARY KEY (id), 
     FOREIGN KEY (country_id) REFERENCES country (id))"; 

create table if not exists state_job_relationship (
     id int(4) not null auto_increment, 
     state_id int(4) not null, FOREIGN KEY (state_id) REFERENCES state (id), 
     job_id int(11) not null, FOREIGN KEY (job_id) REFERENCES sub_jobs (id), 
     PRIMARY KEY (id)); 

create table if not exists main_jobs (
      id int not null auto_increment, primary key(id), 
      company_name varchar(255), 
      job_title varchar(255)); 

create table if not exists sub_jobs (
      id int not null auto_increment, primary key(id), 
      parent_id int(11) not null, FOREIGN KEY (parent_id) REFERENCES main_jobs (id), 
      title varchar(255), 
      description text not null, 
      category int (3), FOREIGN KEY (category) REFERENCES category (id) 
      ); 

這是我想選擇什麼：

從子工作表中的職位名稱，與相應的公司名稱，並從main_jobs和類別表等細節。

所有運作良好，直到我需要選擇每個sub_job屬於這一格式的狀態：狀態1，狀態2，狀態3

select sub_jobs.id as kid, main_jobs.id as parentid, 
    company_name, sub_jobs.description, sub_jobs.title, 
    job_title, category.name as ind, 
    DATE_FORMAT($column_date,'%a, %e %b %Y %T') as d, 
    (select group_concat(name seperator ', ') 
    from state_job_relationship, state 
    where job_id= kid 
    and state.id=state_job_relationship.state_id 
    group by state.id) states 
from sub_jobs, category, main_jobs 
where category.id=sub_jobs.category 
    and main_jobs.id=sub_jobs.parent_id 
order by featured desc , $table.id desc 
limit 100; 

嘗試上述查詢，但它顯示這個錯誤：

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'seperator ', ') from state_job_relationship, state where job_id= kid and state.i' at line 1

請問我什麼不對？

Answer 1

看起來您的錯誤是因爲您在相關子查詢中使用了alais kid。您應該將kid替換爲sub_jobs.id。您還有seperator拼寫錯誤。

所以，你的代碼將是：

select s.id as kid, 
    m.id as parentid, 
    company_name, 
    s.description, 
    s.title, 
    job_title, 
    c.name as ind, 
    DATE_FORMAT($column_date,'%a, %e %b %Y %T') as d, 
    (select group_concat(name SEPARATOR ', ') 
    from state_job_relationship 
    inner join state 
    on state.id=state_job_relationship.state_id 
    where job_id= s.id 
    group by state.id) states 
from sub_jobs s 
inner join category c 
    on c.id=s.category 
inner join main_jobs m 
    on m.id=s.parent_id 
order by featured desc , $table.id desc 
limit 100; 

你會發現，我改變了你的語法使用ANSI JOIN語法，我使用aliasas的表。

其他建議，我將使用子查詢，並加入到子查詢：

select s.id as kid, 
    m.id as parentid, 
    company_name, 
    s.description, 
    s.title, 
    job_title, 
    c.name as ind, 
    DATE_FORMAT($column_date,'%a, %e %b %Y %T') as d, 
    st.states 
from sub_jobs s 
inner join category c 
    on c.id=s.category 
inner join main_jobs m 
    on m.id=s.parent_id 
left join 
(
    select job_id, state.id, group_concat(name SEPARATOR ', ') states 
    from state_job_relationship 
    inner join state 
    on state.id=state_job_relationship.state_id 
    group by state.id, job_id 
) st 
    on st.job_id= s.id 
order by featured desc , $table.id desc 
limit 100;