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mysql join 3 tables and count

开发者 https://www.devze.com 2022-12-24 03:30 出处:网络
Please look at this image here is 3 tables , and out i want is uid from table1 industry fr开发者_JAVA技巧om table 3 of same uid

Please look at this image

mysql join 3 tables and count

here is 3 tables , and out i want is

uid from table1 industry fr开发者_JAVA技巧om table 3 of same uid count of fid from table 2 of same uid

like in the sample example output will be 2 records

Thanks


I don't see any relation with table 1. Here's an example using an inner join between the two tables and grouping by the uid:

SELECT 
  t3.uid, 
  t3.industry, 
  count(t2.fid) 
FROM 
  table3 t3 
INNER JOIN 
  table2 t2 ON t3.uid = t2.uid 
GROUP BY 
  t3.uid


Try with this:

SELECT table1.uid,table3.industry,COUNT(table2.fid) 
FROM table1 
INNER JOIN table3 ON table1.uid=table3.uid
INNER JOIN table2 ON table1.uid=table2.uid
GROUP BY table1.uid, table3.industry

Table1 inner join is useless but could be useful if you'll need to retrieve city or mem_no; in this case, remember to add the field also in GROUP BY clause.

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