mysql中如何使用join获取数据
我有一张桌子: 下表: 我想创建这样的报告 我尝试过以下SQL:mysql中如何使用join获取数据,mysql,database,join,Mysql,Database,Join,我有一张桌子: 下表: 我想创建这样的报告 我尝试过以下SQL: select master_problem.problem, master_problem.sop_reference, master_problem.adidas_spec, count(log_roving_qc.id_problem) as jumlahfrom master_problem inner join log_roving_qc on master_problem.i
select
master_problem.problem,
master_problem.sop_reference,
master_problem.adidas_spec,
count(log_roving_qc.id_problem) as jumlahfrom
master_problem
inner join log_roving_qc
on master_problem.id_problem = log_roving_qc.id_problem
group by master_problem.id_problem
但空数据不显示。我想显示描述为0的空白数据,将
主问题
表左连接到进行计数聚合的子查询:
SELECT
mp.problem,
mp.sop_reference,
mp.adidas_spec,
COALESCE(t.cnt, 0) AS jumlahfrom
FROM master_problem mp
LEFT JOIN
(
SELECT id_problem, COUNT(*) as cnt
FROM log_roving_qc
GROUP BY id_problem
) t
ON mp.id_problem = t.id_problem;
将
master_problem
表左连接到进行计数聚合的子查询:
SELECT
mp.problem,
mp.sop_reference,
mp.adidas_spec,
COALESCE(t.cnt, 0) AS jumlahfrom
FROM master_problem mp
LEFT JOIN
(
SELECT id_problem, COUNT(*) as cnt
FROM log_roving_qc
GROUP BY id_problem
) t
ON mp.id_problem = t.id_problem;
我已尝试修复您实际向我们显示的查询的问题。如果您想要其他内容,请编辑您的问题并使其更清楚。将内部联接更改为左联接我已尝试修复您实际向我们显示的查询中的问题。如果你想要的不是这个,那么编辑你的问题,让它更清楚。将内部连接更改为左连接