Question

I have such a hard time picturing this. I just don’t have the brain to do it.

I have a table called reports.

---------------------------------------------
| report_id   | set_of_bads | field1 | field2 |
---------------------------------------------
| 123         | set1        | qwe    | qwe    |
---------------------------------------------
| 321         | 123112      | ewq    | ewq    |
---------------------------------------------

I have another table called bads. This table contains a list of bad data.

-------------------------------------
| bad_id    | set_it_belongs_to | field2 | field3  |
-------------------------------------
| 1         | set1              | qwe    | qwe     |
-------------------------------------
| 2         | set1              | qee    | tte     |
-------------------------------------
| 3         | set1              | q44w   | 3qwe    |
-------------------------------------
| 4         | 234               | qoow   | 3qwe    |
-------------------------------------

I want to setup a primary key to foreign key relationship. My question is, how do I connect the field set_of_bads to set_it_belongs_to in the bads table. This way if I want to get the entire set of data that is set1 by calling on the reports table I can do it.

Example: hey reports table.. bring up the row that has the report_id 123. Okay thank you.. Now get all the rows from bads that has the set_of_bads value from the row with the report_id 123, in set_it_belongs_to field. Thanks.

Answer 1

try this one,

SELECT  a.*,      -- will display all records from reports table
        b.*       -- will display all records from bads table
FROM    reports a
        INNER JOIN bads b
            ON a.set_of_bads = b.set_it_belongs_to
WHERE   a.report_ID = 123

Update 1

In your CREATE TABLE statement, specify a foreign key constraint on bads table

CREATE TABLE bads
(
bad_id INT AUTO_INCREMENT   ,
 set_it_belongs_to VARCHAR(50),
 field2 VARCHAR(50),
 field3 VARCHAR(50),
 CONSTRAINT bads_pk PRIMARY KEY (bad_id),
 CONSTRAINT bads_fk FOREIGN KEY (set_it_belongs_to) 
    REFERENCES reports(set_of_bads)
);

and make sure that the primary key of reports table is set_of_bads