Question

我有3个表，这些表将合并为1个表。

表1

id|prdct_name|qty
001     A      5
002     B      5
003     C      5

table2

id|prdct_id|price
 1    001    100
 2    001    200
 3    002    150
 4    002    250

table3

id|prdct_id|stock_in|stock_out
 1   001      5           0
 2   001      10          0
 3   002      15          0
 4   002      25          0

我已经尝试过此sql（由于输入错误而更新）

select a.prdct_name as Name, a.qty as QTY,b.price as PRICE, c.stock_in as SIN,c.stock_out as SOUT
from table1 a 
left join table2 b on a.id=b.prdct_id 
left join table3 c on a.id=c.prdct_id
where 1=1 group by b.id,c.id

但结果返回与此表相同的重复

NAME|QTY|PRICE|SIN|SOUT
 A    5   100   5    0
 A    5   100   10   0
 A    5   200   5    0
 A    5   200   10   0
 B    5   150   15   0
 B    5   150   25   0
 B    5   250   15   0
 B    5   250   25   0

结果应该是

 NAME|QTY|PRICE|SIN|SOUT
 A    5   100   5    0
 A    5   200   10   0
 B    5   150   15   0 
 B    5   250   25   0

是否有办法消除重复的问题？尝试与众不同也无济于事。谢谢

Answer 1

看起来您的第二个join应该在id上-并且您的join条件看起来也不正确。

select a.prdct_name as Name, a.qty as QTY, b.price as PRICE, c.stock_in as SIN,c.stock_out as SOUT
from table1 a left join
     table2 b
     on a.id = b.prdct_id left join
     table3 c 
     on a.id = c.id
where 1=1
group by b.id, c.id

Answer 2

更改您的连接密钥，它应为id = product_id，但您尝试使用名称和product_id

select a.prdct_name as Name, a.qty as QTY,b.price as PRICE, c.stock_in as SIN,c.stock_out as SOUT
from table1 a 
left join table2 b on a.id=b.prdct_id 
left join table3 c on a.id=c.prdct_id
where 1=1 group by b.id,c.id

Answer 3

您可以使用SQL关键字DISTINCT选择不重复的行。

示例：

SELECT DISTINCT
  prdct_name as NAME,
  qty as QTY,
  price as PRICE,
  stock_in as SIN,
  stock_out as SOUT
FROM
  table1 a
INNER JOIN
  table2 b ON a.id=b.prdct_id
LEFT JOIN
  table3 c ON b.id=c.id
GROUP BY
  a.id, c.id

Working SQL fiddle

有关 DISTINCT here的更多信息。

如何通过SQL从查询组获取结果而不返回重复

3 个答案: