如何在SQL查询的列中添加值？

Question

I have a question for homework that I do not quite understand. I am being asked to make a query that will result additional values on the same row, Meaning adding more columns as far as I understand. I have no idea how to do it, Unfortunately answers to existing questions here did not seem to answer my question, Maybe I am missing something (I am an SQL noob).

Here is the question:

Write a query that returns the following data: a row per date and abtest, where each row has the impressions and clicks for all the variants and for the control. Variants are identified as vrows where variant_id is not zero, Control is identified as rows where the variant_id is 0.

Eg for the below data, the query will return:

2018-01-01,2,32323,212,95262,354

2018-01-01,5,76675,5454,675675,5454

2018-01-02,2,0,0,7834,99

2018-01-02,5,0,0,9664,144

Table: https://i.ibb.co/kVZTyt5/ob.jpg

So far I tried this:

SELECT date, abtest_id, impressions, clicks FROM table1 WHERE variant_id IS NOT NULL
GROUP BY date, abtest_id;

And this is the result:

2018-01-01 2 5454 11

2018-01-01 5 76675 5454

2018-01-02 2 7834 99

2018-01-02 5 776 12

I don't know how to add more clicks and impressions to the results on the same row, And looking at the example from the question, I don't understand how and why some of these values are there. Any help would be deeply appreciated.

Thanks!

Answer 1

In all DBMS You can use INSERT OR UPDATE.

INSERT for add new values Update for change old values

A Simple Insert syntax is: Insert into tableName (column1, column2,...) Values (value1, value2,...)

A Simple Update syntax is:

Update TableName
Set Column1=value1, Column2=value2

You can use where end of above simple codes

Insert syntax by other table is: Insert into tableName (column1, column2,...) select t.column1,t.column2... From tablename2

A Simple Update syntax is:

Update TableName
Set Column1=value1, Column2=value2
Where colmn1= myValuse

Answer 2

To me you don't need to add columns or rows to your table. You need to select data, and make a few sums on some fields.

I would do something along these lines in MySQL (only full group by mode turned off):

SELECT t.*,
SUM(CASE 
    WHEN variant_id != 0 THEN impressions 
    ELSE 0 
    END) v_impressions,
SUM(CASE 
    WHEN variant_id != 0 THEN clicks 
    ELSE 0 
    END) v_clicks
FROM `tests` as t
GROUP BY date, abtest_id;

Although there may be a simpler syntax.

This selects the data from the rows where variant_id = 0, it sums impressions and clicks where variant_id != 0 and groups by date and abtest_id.