Choose a pair of outcomes when utilizing Group By in a sqlite query

Question

Choose a pair of outcomes when utilizing Group By in a sqlite query

Let's dive into a complex scenario with an illustration:

Consider a sqlite table with various fields (id, language, title, etc.)

Each title can have multiple languages associated with it.

id --  language  --    title          --   publication  --  etc.
----------------------------------------------------------------------
1  --    Eng     --  Les misérables   --      1968      --  ...
2  --    Fr      --  Les misérables   --      1985      --  ...
3  --    Fr      --  Les misérables   --      2001      --  ...
4  --    Eng     --  Brave new world  --      1975      --  ...
5  --    Eng     --  Brave new world  --      1999      --  ...
6  --    Fr      --  Brave new world  --      1999      --  ...

The Challenge:

I want to retrieve the first English and French results in a single SELECT statement.

SELECT (id WHERE language='Eng') AS id1, (id WHERE language='Fr') AS id2 FROM myTable GROUP BY title

In this example, the query would output:

// The following is pseudo-JavaScript code with the SQL challenge
results.rows.item(1).id1 = 1
results.rows.item(1).id2 = 2

results.rows.item(2).id1 = 4
results.rows.item(2).id2 = 6

and so on...

Although the provided syntax is incorrect, can this be achieved through SQL?

javascript sql sqlite select group-by

Answer 1

Answer №1

Let's kick things off with an illustration of correct syntax:

SELECT title
FROM myTable
GROUP BY title

Here, you'll find all the rows from Table myTable organized by Title, for example:

| title | id      | language            | ...
| 'Foo' | [1,4,6] | ['en', 'ger', 'fr'] | ...
| 'Bar' | [2,5]   | ['en', 'it']        | ...
...

The values in [] represent the groups generated by GROUP BY.

If you're only interested in the ids, you can use the group_concat operation on the id column

SELECT title, group_concat(id)
FROM myTable
GROUP BY title

This will provide you with a comma-separated list of ids for each title (refer to ) Alternatively, you could

SELECT ... group_concat(language)

and then combine id and language on the client side if you require both sets of information.

Answer 2

Let's kick things off with an illustration of correct syntax:

SELECT title
FROM myTable
GROUP BY title

Here, you'll find all the rows from Table myTable organized by Title, for example:

| title | id      | language            | ...
| 'Foo' | [1,4,6] | ['en', 'ger', 'fr'] | ...
| 'Bar' | [2,5]   | ['en', 'it']        | ...
...

The values in [] represent the groups generated by GROUP BY.

If you're only interested in the ids, you can use the group_concat operation on the id column

SELECT title, group_concat(id)
FROM myTable
GROUP BY title

This will provide you with a comma-separated list of ids for each title (refer to ) Alternatively, you could

SELECT ... group_concat(language)

and then combine id and language on the client side if you require both sets of information.

Answer 3

Answer №2

Experiment with:

SELECT
     (SELECT id FROM myTable WHERE language='Eng') AS engId, 
     (SELECT id FROM myTable WHERE language='Fr') AS frId,
     title
     FROM myTable GROUP BY title

This can be done if the Subquery returns exactly 1 value; otherwise, it will result in an error.

Answer 4

Experiment with:

SELECT
     (SELECT id FROM myTable WHERE language='Eng') AS engId, 
     (SELECT id FROM myTable WHERE language='Fr') AS frId,
     title
     FROM myTable GROUP BY title

This can be done if the Subquery returns exactly 1 value; otherwise, it will result in an error.

Choose a pair of outcomes when utilizing Group By in a sqlite query

Answer №1

Answer №2

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