SQL - Selecting random rows and combining into a new table - sql

Question

Here's the creation of my tables...
CREATE TABLE questions(
id INTEGER PRIMARY KEY AUTOINCREMENT,
question VARCHAR(256) UNIQUE NOT NULL,
rangeMin INTEGER,
rangeMax INTEGER,
level INTEGER NOT NULL,
totalRatings INTEGER DEFAULT 0,
totalStars INTEGER DEFAULT 0
);
CREATE TABLE games(
id INTEGER PRIMARY KEY AUTOINCREMENT,
level INTEGER NOT NULL,
inclusive BOOL NOT NULL DEFAULT 0,
active BOOL NOT NULL DEFAULT 0,
questionCount INTEGER NOT NULL,
completedCount INTEGER DEFAULT 0,
startTime DATETIME DEFAULT CURRENT_TIMESTAMP
);
CREATE TABLE gameQuestions(
gameId INTEGER,
questionId INTEGER,
asked BOOL DEFAULT 0,
FOREIGN KEY(gameId) REFERENCES games(id),
FOREIGN KEY(questionId) REFERENCES questions(id)
);
I'll explain the full steps that I'm doing, and then I'll ask for input.
I need to...
Using a games.id value, lookup the games.questionCount and games.level for that game.
Now since I have games.questionCount and games.level, I need to look at all of the rows in questions table with questions.level = games.level and select games.questionCount of them at random.
Now with the rows (aka questions) I got from step 2, I need to put them into gameQuestions table using the games.id value and the questions.id value.
Whats the best way to accomplish this? I could do it with several different sql queries, but I feel like someone really skilled with sql could make it happen a bit more efficient. I am using sqlite3.

Answer 1

This does it in one statement. Let's assume :game_id to be the game id you want to process.
insert into gameQuestions (gameId, questionId)
select :game_id, id
from questions
where level = (select level from games where id = :game_id)
order by random()
limit (select questionCount from games where id = :game_id);
#Tony: sqlite doc says LIMIT takes an expression. The above statement works fine using sqlite 3.8.0.2 and produces the desired results. I have not tested an older version.