I get the name and address data from the generic question / answer data to create some normalized reporting database.
The query that I have uses group_concat and works for individual sets of questions, but not for multiple sets.
I tried to simplify what I am doing using only first and last name and only 3 entries, 2 for 1 person and 1 for another. In fact, although there are over 300,000 entries.
Example results with qs.Id = 1 .
QuestionSetId Forename Surname ------------------------------------------------------- 1 Bob Jones
Example results with qs.Id IN (1, 2, 3) .
QuestionSetId Forename Surname ------------------------------------------------------- 3 Bob,Bob,Frank Jones,Jones,Smith
What I would like to see for qs.Id IN (1, 2, 3) .
QuestionSetId Forename Surname ------------------------------------------------------- 1 Bob Jones 2 Bob Jones 3 Frank Smith
So, how can I make a second example, return a separate row for each dataset of name and address?
I understand that the current way of storing data is “doubtful,” but I cannot change the way I store data.
I can get sets of individual answers , but not sure how to combine the others.
My simplified scheme that I cannot change:
CREATE TABLE StaticQuestion ( Id INT NOT NULL, StaticText VARCHAR(500) NOT NULL); CREATE TABLE Question ( Id INT NOT NULL, Text VARCHAR(500) NOT NULL); CREATE TABLE StaticQuestionQuestionLink ( Id INT NOT NULL, StaticQuestionId INT NOT NULL, QuestionId INT NOT NULL, DateEffective DATETIME NOT NULL); CREATE TABLE Answer ( Id INT NOT NULL, Text VARCHAR(500) NOT NULL); CREATE TABLE QuestionSet ( Id INT NOT NULL, DateEffective DATETIME NOT NULL); CREATE TABLE QuestionAnswerLink ( Id INT NOT NULL, QuestionSetId INT NOT NULL, QuestionId INT NOT NULL, AnswerId INT NOT NULL, StaticQuestionId INT NOT NULL);
Some sample data is for first and last name only.
INSERT INTO StaticQuestion (Id, StaticText) VALUES (1, 'FirstName'), (2, 'LastName'); INSERT INTO Question (Id, Text) VALUES (1, 'What is your first name?'), (2, 'What is your forename?'), (3, 'What is your Surname?'); INSERT INTO StaticQuestionQuestionLink (Id, StaticQuestionId, QuestionId, DateEffective) VALUES (1, 1, 1, '2001-01-01'), (2, 1, 2, '2008-08-08'), (3, 2, 3, '2001-01-01'); INSERT INTO Answer (Id, Text) VALUES (1, 'Bob'), (2, 'Jones'), (3, 'Bob'), (4, 'Jones'), (5, 'Frank'), (6, 'Smith'); INSERT INTO QuestionSet (Id, DateEffective) VALUES (1, '2002-03-25'), (2, '2009-05-05'), (3, '2009-08-06'); INSERT INTO QuestionAnswerLink (Id, QuestionSetId, QuestionId, AnswerId, StaticQuestionId) VALUES (1, 1, 1, 1, 1), (2, 1, 3, 2, 2), (3, 2, 2, 3, 1), (4, 2, 3, 4, 2), (5, 3, 2, 5, 1), (6, 3, 3, 6, 2);
Just in case, SQLFiddle here are three queries from the examples I am associated with:
1: - working request, but only for 1 data set.
SELECT MAX(QuestionSetId) AS QuestionSetId, GROUP_CONCAT(Forename) AS Forename, GROUP_CONCAT(Surname) AS Surname FROM (SELECT x.QuestionSetId, CASE x.StaticQuestionId WHEN 1 THEN Text END AS Forename, CASE x.StaticQuestionId WHEN 2 THEN Text END AS Surname FROM (SELECT (SELECT link.StaticQuestionId FROM StaticQuestionQuestionLink link WHERE link.Id = qa.QuestionId AND link.DateEffective <= qs.DateEffective AND link.StaticQuestionId IN (1, 2) ORDER BY link.DateEffective DESC LIMIT 1) AS StaticQuestionId, a.Text, qa.QuestionSetId FROM QuestionSet qs INNER JOIN QuestionAnswerLink qa ON qs.Id = qa.QuestionSetId INNER JOIN Answer a ON qa.AnswerId = a.Id WHERE qs.Id IN (1)) x) y
2: - working request, but undesirable results for several data sets.
SELECT MAX(QuestionSetId) AS QuestionSetId, GROUP_CONCAT(Forename) AS Forename, GROUP_CONCAT(Surname) AS Surname FROM (SELECT x.QuestionSetId, CASE x.StaticQuestionId WHEN 1 THEN Text END AS Forename, CASE x.StaticQuestionId WHEN 2 THEN Text END AS Surname FROM (SELECT (SELECT link.StaticQuestionId FROM StaticQuestionQuestionLink link WHERE link.Id = qa.QuestionId AND link.DateEffective <= qs.DateEffective AND link.StaticQuestionId IN (1, 2) ORDER BY link.DateEffective DESC LIMIT 1) AS StaticQuestionId, a.Text, qa.QuestionSetId FROM QuestionSet qs INNER JOIN QuestionAnswerLink qa ON qs.Id = qa.QuestionSetId INNER JOIN Answer a ON qa.AnswerId = a.Id WHERE qs.Id IN (1, 2, 3)) x) y
3: - a working request for several data sets for only 1 field (response).
SELECT qs.Id AS QuestionSet, a.Text AS Answer FROM QuestionSet qs INNER JOIN QuestionAnswerLink qalink ON qs.Id = qalink.QuestionSetId INNER JOIN StaticQuestionQuestionLink sqqlink ON qalink.QuestionId = sqqlink.QuestionId INNER JOIN Answer a ON qalink.AnswerId = a.Id WHERE sqqlink.StaticQuestionId = 1 AND sqqlink.DateEffective = (SELECT DateEffective FROM StaticQuestionQuestionLink WHERE StaticQuestionId = 1 AND DateEffective <= qs.DateEffective ORDER BY DateEffective DESC LIMIT 1)