Join three Tables with 2 different common Columns

Question

I have three tables:

Table1: COL1 COL2
Table2: COL2 COL3 COL5
Table3: COL3 COL4

And I want to select the COL1 from Table1, COL5 from TABLE2 and COL4 from Table3

It likes two join table, but when I use the following query it doesn't work, COL5 is blank.

SELECT Table1.COL1, Table2.COL5, Table3.COL4 

FROM table3
INNER JOIN table2 ON table3.col3 = table2.col3
INNER JOIN table1 ON table1.col2 = table2.col2

Please help.

PS I copied a previous similar example but different output.

provide your sample data and expected output in table format — Fahmi
Your query looks fine, only issue can be data. It will be good if you share sample data. — PSK
If you are getting rows, but COL5 is blank, then COL5 simply contains null or space only. It can also be a display issue, e.g. the value in COL5 starts with a line feed character and your tool doesn't show the following text. — Thorsten Kettner

FPA FPA · Accepted Answer · 2019-02-19T06:37:01

It seems that there isn't relational data between table 3 and table 2

SELECT Table1.COL1, Table2.COL5, Table3.COL4

table3.col3, table2.col3 --if this comes up as null then Table2.COL5 would be null
table1.col2, table2.col2 --if this comes up as null then Table2.COL5 would also be null

FROM table3
LEFT OUTER JOIN table2 ON table3.col3 = table2.col3
LEFT OUTER JOIN table1 ON table1.col2 = table2.col2

With an INNER JOIN all join conditions will need to be true in order to return results.

Consider changing your INNER JOIN order or use LEFT OUTER JOIN.

Join three Tables with 2 different common Columns

1 Answers