Multiple inner joins with multiple tables
So I have four tables. Each table has a single id for the previous table id. So my in click table has an id and an id for the ad from which it came. In the ad table, it has an id for the ad and one for the campaign it's from. So here's an example.
Table4 -
id company table_id
11 hp 20
12 apple 23
13 kohls 26
14 target 21
15 borders 28
Table3 -
id value table2_id
21 ks 53
22 al 54
23 tx 53
24 fl 55
25 co 51
Table2 -
id value table1_id
51 ks 34
52 al 34
53 tx 33
54 fl 35
55 co 31
Table1 -
id value
31 ks
32 al
33 tx
34 fl
35 co
So to find out where the values in Table 4 came from, I need to work back through each table开发者_高级运维 and check which id they have. Basically, I want to know which values in table 1 are associated with the values in table 4.
This of table 4 as visitors to a website and Table 1 as internet ads. I want to know which visitors came from which ads. Unfortunately, the data is set up so that I can only take single steps back from visitor to source to ad group to ad. Does that make sense?
Anyways, I'm wondering if using 4 innner joins was the optimal strategy for this problem or is there some simpler mysql solution that i'm not aware of.
Inner joins are probably the best method, and you only need 3.
This will give you a result set with two columns: company and associated values.
SELECT Table4.company, table1.id, table1.value
FROM Table1
INNER JOIN Table2
ON Table2.table1_id = Table1.id
INNER JOIN Table3
ON Table3.table2_id = Table2.id
INNER JOIN Table4
ON Table4.table3_id = Table3.id
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