使用DISTINCT消除重複

-1

我有這些3 表。我執行下面的查詢，但查詢回報5個記錄101個2記錄201使用DISTINCT消除重複

questions_tbl     answers_tbl     meter_tbl 
qid qtype other_columns  qid(fk) other_columns  qtype  other_columns 
    1  101      1       101 
    2  201      2       101 
    3  101      3       101 
    4  101      4       201 

SELECT * 
FROM answers, meter, questions 
WHERE questions.qid=answers.question_id AND questions.subject_type = meter.subject_type

ALSO我試圖DISTINCT

SELECT DISTINCT 
FROM answers, meter, questions 
WHERE questions.qid=answers.question_id AND questions.subject_type = meter.subject_type

來源

2015-01-04 pmcs management

我嘗試SELECT DISTINCT似乎沒有工作？ –

你在說什麼查詢？ – baao

是的，請將您的問題添加到您的問題中，以便我們提供幫助。 – Tom

嘗試DISTINCT這樣。

SELECT DISTINCT questions.qtype,other_column FROM answers, meter, questions 
WHERE questions.qid=answers.question_id AND questions.subject_type = 
meter.subject_type

使用GROUP BY

SELECT * FROM answers, meter, questions 
WHERE questions.qid=answers.question_id AND questions.subject_type = meter.subject_type 
GROUP BY questions.qtype

來源

2015-01-04 08:09:45

使用DISTINCT消除重複

回答

相關問題