连接具有相同列标题但具有不同列标题的2个表

Question

How do I join 2 tables that have all of the same column headers but one?

The other 3 columns are all the same then one table has the column header "January" and the other table has the column header "February"

So I would like to end up with 5 total columns in new table

I would also like all of the data in there even if there are duplicates. Before I used a union all but now I cannot do that because not all my headers are the same.

Thanks!

Answer 1

You can use UNION and rename one of your columns:

SELECT id, name, age, xxx FROM table1
UNION
SELECT id, name, age, yyy AS xxx FROM table2

If you add more information, I can elaborate my answer

Answer 2

select tb1.col1, tb1.col2, tb1.col3, tb2.col3 from tb1
inner join tb2 on (tb1.col1 = tb2.col1)

Answer 3

Assuming uniqueness when just considering the three columns, joining them

SELECT tab1.col1, 
       tab1.col2, 
       tab1.col3, 
       tab1.january, 
       tab2.february 
FROM   tab1, 
       tab2 
WHERE  tab1.col1 = tab2.col1 
       AND tab1.col2 = tab2.col2 
       AND tab1.col3 = tab2.col3 

Answer 4

This assumes all rows in tblA have corresponding ones in tblB and vice versa:

SELECT * FROM tblA INNER JOIN tblB USING (col1, col2, col3);

If that is not the case, and depending on the data (if tbl1 . january can have legitimate null values, this won't work), you could try something like ( didn't check for sure, might need massaged with parenthesis, subselecting, etc... ):

SELECT *
FROM tbl1 
LEFT JOIN tbl2 USING (col1, col2, col3)
UNION ALL
SELECT * FROM tbl2 LEFT JOIN tbl1 USING (col1, col2, col3)
HAVING tbl1.`january` IS NULL
;