group-concat

问题 SELECT *, Group_concat(rating) AS rating_total, Sum(rating_total) AS rating_sum, Avg(rating_sum) AS rating_avg FROM ratings GROUP BY pid For some reason the sum and average don't execute....how do you make this statement work? 回答1: Because of the way that SQL compiles the queries (I assume MySQL since you're using GROUP_CONCAT), you cannot reference aliased column names before the order by clause. The SUM and AVG functions are not procedural . They are done in parallel. Which means that they

问题 SELECT *, Group_concat(rating) AS rating_total, Sum(rating_total) AS rating_sum, Avg(rating_sum) AS rating_avg FROM ratings GROUP BY pid For some reason the sum and average don't execute....how do you make this statement work? 回答1: Because of the way that SQL compiles the queries (I assume MySQL since you're using GROUP_CONCAT), you cannot reference aliased column names before the order by clause. The SUM and AVG functions are not procedural . They are done in parallel. Which means that they

问题 On my previous question How to group array value duplicate and customize the display of the results of the array in html table? which has not been answered yet, I opt in other way to display the 5 rows only. This is the database: lid class_id class Q1-2 Q3-4 total item_group ----- ------- ----- ----- ----- ----- ---------- 1 73 Leader 5000 50000 10000 33 1 77 Consultant 4000 4000 8000 33 1 83 Coordinator 3000 3000 6000 33 2 73 Leader 10000 10000 20000 33 2 76 Staff 4000 4000 8000 33 2 77

问题 I have the following query: SELECT *, RES.res_id 'ID', RES.RES_Title 'Title', GROUP_CONCAT(DISTINCT T.T_Name separator ', ') 'Topics', GROUP_CONCAT(DISTINCT CH.CH_Code separator ', ') 'Chapters' FROM Resources RES LEFT JOIN topic_to_resource RT ON RT.RT_ResourceID = RES.RES_ID LEFT JOIN topics T on T.T_ID = RT.RT_TopicID LEFT JOIN topic_to_chapter TCH on TCH.TCH_TopicID = T.T_ID LEFT JOIN chapters CH ON CH.CH_ID = TCH.TCH_FrameworkID WHERE RES_Status = 'Active' GROUP BY RES.RES_ID ORDER BY

问题 Let's say my DB Scheme is as follows: T_PRODUCT id_product (int, primary) two entries: (id_product =1) , (id_product =2) T_USER id_user (int, primary) id_product (int, foreign key) name_user (varchar) two entries: (id_product=1,name_user='John') , (id_product=1,name_user='Mike') If I run a first query to get all products with their users (if there are any), I get this: SELECT T_PRODUCT.id_product, T_USER.name_user FROM T_PRODUCT LEFT JOIN T_USER on T_USER.id_product = T_PRODUCT.id_product; >>

问题 Let's say my DB Scheme is as follows: T_PRODUCT id_product (int, primary) two entries: (id_product =1) , (id_product =2) T_USER id_user (int, primary) id_product (int, foreign key) name_user (varchar) two entries: (id_product=1,name_user='John') , (id_product=1,name_user='Mike') If I run a first query to get all products with their users (if there are any), I get this: SELECT T_PRODUCT.id_product, T_USER.name_user FROM T_PRODUCT LEFT JOIN T_USER on T_USER.id_product = T_PRODUCT.id_product; >>

问题 This is my table: id fk_company 1 2 2 2 3 2 4 4 5 4 6 11 7 11 8 11 9 12 The result i want should be string "3, 2, 3, 1" because this is just part of my complex query string. I tried to use this query: SELECT GROUP_CONCAT(COUNT(id) SEPARATOR ", ") FROM `table` GROUP BY fk_company; But I got an error: Error Number: 1111 Invalid use of group function I have a feeling COUNT, MAX, MIN or SUM can't be used in GROUP_CONCAT. If so, do you know another way to do this. 回答1: You need to COUNT() with

问题 Is this possible ? Let's say I have a list of addresses, with a lot of duplicate entries. I need to filter out all the duplicates, because some addresses have slightly different names but the same postalcode and telephone number. First I do a GROUP BY on postalcode and telephone. SELECT name, address, postalcode, place, phone FROM addresses GROUP BY postalcode, phone But then I get random names. I would like to get the best name, that is, the name with the most entries per postalcode/phone.

问题 I have two tables like this profile_answers +---------+------------+ | id | class_name | +---------+------------+ | 1 | Class 1 | | 2 | Class 2 | | 3 | Class 1 | +---------+------------+ educations +---------+--------------------+------------+ | id | profile_answers_id | sample | +---------+--------------------+------------+ | 1 | 1 | 1234 | | 2 | 1 | 2334 | | 3 | 1 | 3434 | +---------+------------+--------------------+ I ran the query, select educations.profile_answer_id, GROUP_CONCAT

问题 I am using MySQL. I have 3 Table as below. Table : subject_Master -------------------------- subjectId | subjectShortName ---------------------------------- 1 | English 2 | French 3 | German 4 | Latin ---------------------------------- Table : class_Master ----------------------------------- classId | className ---------------------------------- 1 | Rose 2 | Dasy 3 | Lily Table : subjectAllocation ------------------------------------------ allocationId | classId | subjectId ------------------