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  • performance issue: difference between select s.* vs select *

    - by kamil
    Recently I had some problem in performance of my query. The thing is described here: poor Hibernate select performance comparing to running directly - how debug? After long time of struggling, I've finally discovered that the query with select prefix like: select sth.* from Something as sth... Is 300x times slower then query started this way: select * from Something as sth.. Could somebody help me, and asnwer why is that so? Some external documents on this would be really useful. The table used for testing was: SALES_UNIT table contains some basic info abot sales unit node such as name and etc. The only association is to table SALES_UNIT_TYPE, as ManyToOne. The primary key is ID and field VALID_FROM_DTTM which is date. SALES_UNIT_RELATION contains relation PARENT-CHILD between sales unit nodes. Consists of SALES_UNIT_PARENT_ID, SALES_UNIT_CHILD_ID and VALID_TO_DTTM/VALID_FROM_DTTM. No association with any tables. The PK here is ..PARENT_ID, ..CHILD_ID and VALID_FROM_DTTM The actual query I've done was: select s.* from sales_unit s left join sales_unit_relation r on (s.sales_unit_id = r.sales_unit_child_id) where r.sales_unit_child_id is null select * from sales_unit s left join sales_unit_relation r on (s.sales_unit_id = r.sales_unit_child_id) where r.sales_unit_child_id is null Same query, both uses left join and only difference is with select.

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  • Is count(*) really expensive ?

    - by Anil Namde
    I have a page where I have 4 tabs displaying 4 different reports based off different tables. I obtain the row count of each table using a select count(*) from <table> query and display number of rows available in each table on the tabs. As a result, each page postback causes 5 count(*) queries to be executed (4 to get counts and 1 for pagination) and 1 query for getting the report content. Now my question is: are count(*) queries really expensive -- should I keep the row counts (at least those that are displayed on the tab) in the view state of page instead of querying multiple times? How expensive are COUNT(*) queries ?

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  • Databinding in combo box

    - by muralekarthick
    Hi I have two forms, and a class, queries return in Stored procedure. Stored Procedure: ALTER PROCEDURE [dbo].[Payment_Join] @reference nvarchar(20) AS BEGIN -- SET NOCOUNT ON added to prevent extra result sets from -- interfering with SELECT statements. SET NOCOUNT ON; -- Insert statements for procedure here SELECT p.iPaymentID,p.nvReference,pt.nvPaymentType,p.iAmount,m.nvMethod,u.nvUsers,p.tUpdateTime FROM Payment p, tblPaymentType pt, tblPaymentMethod m, tblUsers u WHERE p.nvReference = @reference and p.iPaymentTypeID = pt.iPaymentTypeID and p.iMethodID = m.iMethodID and p.iUsersID = u.iUsersID END payment.cs using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Data; using System.Data.SqlClient; using System.Windows.Forms; namespace Finance { class payment { string connection = global::Finance.Properties.Settings.Default.PaymentConnectionString; #region Fields int _paymentid = 0; string _reference = string.Empty; string _paymenttype; double _amount = 0; string _paymentmethod; string _employeename; DateTime _updatetime = DateTime.Now; #endregion #region Properties public int paymentid { get { return _paymentid; } set { _paymentid = value; } } public string reference { get { return _reference; } set { _reference = value; } } public string paymenttype { get { return _paymenttype; } set { _paymenttype = value; } } public string paymentmethod { get { return _paymentmethod; } set { _paymentmethod = value; } } public double amount { get { return _amount;} set { _amount = value; } } public string employeename { get { return _employeename; } set { _employeename = value; } } public DateTime updatetime { get { return _updatetime; } set { _updatetime = value; } } #endregion #region Constructor public payment() { } public payment(string refer) { reference = refer; } public payment(int paymentID, string Reference, string Paymenttype, double Amount, string Paymentmethod, string Employeename, DateTime Time) { paymentid = paymentID; reference = Reference; paymenttype = Paymenttype; amount = Amount; paymentmethod = Paymentmethod; employeename = Employeename; updatetime = Time; } #endregion #region Methods public void Save() { try { SqlConnection connect = new SqlConnection(connection); SqlCommand command = new SqlCommand("payment_create", connect); command.CommandType = CommandType.StoredProcedure; command.Parameters.Add(new SqlParameter("@reference", reference)); command.Parameters.Add(new SqlParameter("@paymenttype", paymenttype)); command.Parameters.Add(new SqlParameter("@amount", amount)); command.Parameters.Add(new SqlParameter("@paymentmethod", paymentmethod)); command.Parameters.Add(new SqlParameter("@employeename", employeename)); command.Parameters.Add(new SqlParameter("@updatetime", updatetime)); connect.Open(); command.ExecuteScalar(); connect.Close(); } catch { } } public void Load(string reference) { try { SqlConnection connect = new SqlConnection(connection); SqlCommand command = new SqlCommand("Payment_Join", connect); command.CommandType = CommandType.StoredProcedure; command.Parameters.Add(new SqlParameter("@Reference", reference)); //MessageBox.Show("ref = " + reference); connect.Open(); SqlDataReader reader = command.ExecuteReader(); while (reader.Read()) { this.reference = Convert.ToString(reader["nvReference"]); // MessageBox.Show(reference); // MessageBox.Show("here"); // MessageBox.Show("payment type id = " + reader["nvPaymentType"]); // MessageBox.Show("here1"); this.paymenttype = Convert.ToString(reader["nvPaymentType"]); // MessageBox.Show(paymenttype.ToString()); this.amount = Convert.ToDouble(reader["iAmount"]); this.paymentmethod = Convert.ToString(reader["nvMethod"]); this.employeename = Convert.ToString(reader["nvUsers"]); this.updatetime = Convert.ToDateTime(reader["tUpdateTime"]); } reader.Close(); } catch (Exception ex) { MessageBox.Show("Check it again" + ex); } } #endregion } } i have already binded the combo box items through designer, When i run the application i just get the reference populated in form 2 and combo box just populated not the particular value which is fetched. New to c# so help me to get familiar

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  • How to avoid geometric slowdown with large Linq transactions?

    - by Shaul
    I've written some really nice, funky libraries for use in LinqToSql. (Some day when I have time to think about it I might make it open source... :) ) Anyway, I'm not sure if this is related to my libraries or not, but I've discovered that when I have a large number of changed objects in one transaction, and then call DataContext.GetChangeSet(), things start getting reaalllly slooowwwww. When I break into the code, I find that my program is spinning its wheels doing an awful lot of Equals() comparisons between the objects in the change set. I can't guarantee this is true, but I suspect that if there are n objects in the change set, then the call to GetChangeSet() is causing every object to be compared to every other object for equivalence, i.e. at best (n^2-n)/2 calls to Equals()... Yes, of course I could commit each object separately, but that kinda defeats the purpose of transactions. And in the program I'm writing, I could have a batch job containing 100,000 separate items, that all need to be committed together. Around 5 billion comparisons there. So the question is: (1) is my assessment of the situation correct? Do you get this behavior in pure, textbook LinqToSql, or is this something my libraries are doing? And (2) is there a standard/reasonable workaround so that I can create my batch without making the program geometrically slower with every extra object in the change set?

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  • how to find end of quarter given a date in the quarter

    - by Ramy
    If i'm given a date (say @d = '11-25-2010'), how can I determine the end of the quarter from that date. I'd like to use a timestamp one second before midnight. I can get this: select dateadd(qq, datediff(qq, 0, getdate()), 0) as quarterStart which gives me: '10-1-2010' and I use this for one second before midnight of a given day: select DateAdd(second, -1, DateAdd(day, DateDiff(day, 0, @d))+1, 0) ) AS DayEnd in the end, a quarterEnd method would give me '12-31-2010 23:59:00'

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  • PHP MSSQL : How to display output when query return no row

    - by vamps
    i have a problem with my PHP-MSSQL query. i have a join table that need to give a result something be like this: Department Group A Group B Total A+B WORKHOUR A OTHOUR A WORKHOUR B OTHOUR B WORKHOUR OTHOUR HR 10 15 25 0 35 15 IT 5 5 5 5 Admin 12 12 12 12 the query will count how many employee as per given date (admin will enter data and once submitted, the query will give the above result). The problem is, the final output is a mess when there's no row to be displayed. the column is shifted to the right. i.e: only Group A in IT only Group B in Admin Department Group A Group B Total A+B WORKHOUR A OTHOUR A WORKHOUR B OTHOUR B WORKHOUR OTHOUR HR 10 15 25 0 35 15 IT 5 5 5 5 Admin 12 12 12 12 my question is, how to prevent this to happen? i've tried everything with While.... if else.. but the result is still the same. how to display output "0" if no rows to return? echo "0"; this is my QUERY: select DD.DPT_ID,DPT.DEPARTMENT_NAME,TU.EMP_GROUP, sum(DD.WORK_HOUR) AS WORK_HOUR, sum(DD.OT_HOUR) AS OT_HOUR FROM DEPARTMENT_DETAIL DD left join DEPARTMENT DPT ON (DD.DEPT_ID=DPT.DEPT_ID) LEFT JOIN TBL_USERS TU ON (TU.EMP_ID=DD.EMP_ID) WHERE DD_DATE>='2012-01-01' AND DD_DATE<='2012-01-31' AND TU.EMP_GROUP!=2 GROUP BY DD.DEPT_ID, DPT.DEPARTMENT_NAME,TU.EMP_GROUP ORDER BY DPT.DEPARTMENT_NAME this is one of the logic that i've used, but doesn't return the result that i want:: while($row = mssql_fetch_array($displayResult)) { if ((!$row["WORK_HOUR"])&&(!$row["OT_HOUR"])) { echo "<td >"; echo "empty"; echo "&nbsp;</td>"; echo "<td >"; echo "empty"; echo "&nbsp;</td>"; } else { echo "<td>"; echo $row["WORK_HOUR"]; echo "&nbsp;</td>"; echo "<td>"; echo $row["OT_HOUR"]; echo "&nbsp;</td>"; } } please help. i've been doing this for 2 days. @__@

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  • Extract time part from TimeStamp column in ORACLE

    - by RRUZ
    Actually i' am using MyTimeStampField-TRUNC(MyTimeStampField) to extract the time part from an timestamp column in Oracle. SELECT CURRENT_TIMESTAMP-TRUNC(CURRENT_TIMESTAMP) FROM DUAL this return +00 13:12:07.100729 this work ok for me, to extract the time part from an timestamp field, but i' m wondering if exist a better way (may be using an built-in function of ORACLE) to do this? Thanks.

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  • how can add an extra select in this query?

    - by BulgedSnowy
    i've three tables related. images: id | filename | filesize | ... nodes: image_id | tag_id tags: id | name And i'm using this query to search images containing x tags SELECT images.* FROM images INNER JOIN nodes ON images.id = nodes.image_id WHERE tag_id IN (SELECT tags.id FROM tags WHERE tags.tag IN ("tag1","tag2")) GROUP BY images.id HAVING COUNT(*)= 2 The problem is that i need to retrieve also all images contained by the retrieved image, and i need this in the same query. This the actual query wich search retrieve all tags contained by the image: SELECT tag FROM nodes JOIN tags ON nodes.tag_id = tags.id WHERE image_id = images.id and nodes.private = images.private ORDER BY tag How can i mix this two to have only one query?

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  • Which MySql line is faster:

    - by Camran
    I have a classified_id variable which matches one document in a MySql table. I am currently fetching the information about that one record like this: SELECT * FROM table WHERE table.classified_id = $classified_id I wonder if there is a faster approach, for example like this: SELECT 1 FROM table WHERE table.classified_id = $classified_id Wont the last one only select 1 record, which is exactly what I need, so that it doesn't have to scan the entire table but instead stops searching for records after 1 is found? Or am I dreaming this? Thanks

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  • mysql: inserting data and autoincrement

    - by every_answer_gets_a_point
    i am converting from access to mysql i have a table in access where one of the columns is an autonumber when i transfer the data into the mysql database (where i also have a column that is auto_increment), should i be transfering the auto_increment data into the auto_increment column, or will it auto_increment itself? how do i ensure that if i do not transfer the autoincrement data from access, that it auto_increments properly?

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  • I want to do a sql update loop statement, by using the do--while in php

    - by Jean
    Hello, I want to loop the update statement, but it only loops once. Here is the code I am using: do { mysql_select_db($database_ll, $ll); $query_query= "update table set ex='$71[1]' where field='val'"; $query = mysql_query($query_query, $ll) or die(mysql_error()); $row_domain_all = mysql_fetch_assoc($query); } while ($row_query = mysql_fetch_assoc($query)); Thanks Jean

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  • Get count matches in query on large table very slow

    - by Roy Roes
    I have a mysql table "items" with 2 integer fields: seid and tiid The table has about 35000000 records, so it's very large. seid tiid ----------- 1 1 2 2 2 3 2 4 3 4 4 1 4 2 The table has a primary key on both fields, an index on seid and an index on tiid. Someone types in 1 or more tiid values and now I would like to get the seid with most results. For example when someone types 1,2,3, I would like to get seid 2 and 4 as result. They both have 2 matches on the tiid values. My query so far: SELECT COUNT(*) as c, seid FROM items WHERE tiid IN (1,2,3) GROUP BY seid HAVING c = (SELECT COUNT(*) as c, seid FROM items WHERE tiid IN (1,2,3) GROUP BY seid ORDER BY c DESC LIMIT 1) But this query is extremly slow, because of the large table. Does anyone know how to construct a better query for this purpose?

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  • Select rows where column LIKE dictionary word

    - by Gerve
    I have 2 tables: Dictionary - Contains roughly 36,000 words CREATE TABLE IF NOT EXISTS `dictionary` ( `word` varchar(255) NOT NULL, PRIMARY KEY (`word`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1; Datas - Contains roughly 100,000 rows CREATE TABLE IF NOT EXISTS `datas` ( `ID` int(11) NOT NULL AUTO_INCREMENT, `hash` varchar(32) NOT NULL, `data` varchar(255) NOT NULL, `length` int(11) NOT NULL, `time` int(11) NOT NULL, PRIMARY KEY (`ID`), UNIQUE KEY `hash` (`hash`), KEY `data` (`data`), KEY `length` (`length`), KEY `time` (`time`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=105316 ; I would like to somehow select all the rows from datas where the column data contains 1 or more words. I understand this is a big ask, it would need to match all of these rows together in every combination possible, so it needs the best optimization. I have tried the below query, but it just hangs for ages: SELECT `datas`.*, `dictionary`.`word` FROM `datas`, `dictionary` WHERE `datas`.`data` LIKE CONCAT('%', `dictionary`.`word`, '%') AND LENGTH(`dictionary`.`word`) > 3 ORDER BY `length` ASC LIMIT 15 I have also tried something similar to the above with a left join, and on clause that specified the like statement.

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  • Help me choose between XML or SQL Lite on android

    - by Ngetha
    I have an android app that periodically, say once a week downloads content from a server in XML. The content is used by the app, different Acitivities use different parts of the content. My question is a design one, should I save the data in SQlite or just keep it as an XML file, which one would be faster to read? The app can only use one content piece at a time, which means subsequent XML content downloads replace the old one.

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  • how do I integrate the aspnet_users table (asp.net membership) into my existing database

    - by ooo
    i have a database that already has a users table COLUMNS: userID - int loginName - string First - string Last - string i just installed the asp.net membership table. Right now all of my tables are joined into my users table foreign keyed into the "userId" field How do i integrate asp.net_users table into my schema? here are the ideas i thought of: Add a membership_id field to my users table and on new inserts, include that new field in my users table. This seems like the cleanest way as i dont need to break any existing relationships. break all existing relationship and move all of the fields in my user table into the asp.net_users table. This seems like a pain but ultimately will lead to the most simple, normalized solution any thoughts?

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  • Manual Linq to SQL entity framework mapping

    - by kprobst
    I've been playing with the O/R designer in VS and I was wondering if someone could shed come light on this. I'm used to OR mappers that are largely manual (homegrown and e.g., NHibernate). I don't mind encoding the entity classes myself, since they don't change all that often to begin with, and I have this irrational fear of designers and auto generated code as it is. I have noticed that the generated entity classes contain a lot of boilerplate extensibility methods, e.g. On[Property]Changed() and so on where [Property] is a mapped member of the class. These are placed in the setters of the property accessors. I assume it's OK if I don't include these when I do my hand coding, correct? They would be nice if I needed some sort of interception pattern but that's certainly not the case. I guess I just need to know if any of those methods are required by the entity framework to keep track of changes to the mapping types in order for things to work when updating the database. Thanks!

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  • Running an application from an USB device...

    - by Workshop Alex
    I'm working on a proof-of-concept application, containing a WCF service with console host and client, both on a single USB device. On the same device I will also have the client application which will connect to this service. The service uses the entity framework to connect to the database, which in this POC will just return a list of names. If it works, it will be used for a larger project. Creating the client and service was easy and this works well from USB. But getting the service to connect to the database isn't. I've found this site, suggesting that I should modify machine.config but that stops the XCopy deployment. This project cannot change any setting of the PC, so this suggestion is bad. I cannot create a deployment setup either. The whole thing just needs to run from USB disk. So, how do I get it to run? (The service just selects a list of names from the database, which it returns to the client. If this POC works, it will do far more complex things!)

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  • php while loop throwing a error over a $var < 10 statement

    - by William
    Okay, so for some reason this is giving me a error as seen here: http://prime.programming-designs.com/test_forum/viewboard.php?board=0 However if I take away the '&& $cur_row < 10' it works fine. Why is the '&& $cur_row < 10' causing me a problem? $sql_result = mysql_query("SELECT post, name, trip, Thread FROM (SELECT MIN(ID) AS min_id, MAX(ID) AS max_id, MAX(Date) AS max_date FROM test_posts GROUP BY Thread ) t_min_max INNER JOIN test_posts ON test_posts.ID = t_min_max.min_id WHERE Board=".$board." ORDER BY max_date DESC", $db); $num_rows = mysql_num_rows($sql_result); $cur_row = 0; while($row = mysql_fetch_row($sql_result) && $cur_row < 10) { $sql_max_post_query = mysql_query("SELECT ID FROM test_posts WHERE Thread=".$row[3].""); $post_num = mysql_num_rows($sql_max_post_query); $post_num--; $cur_row++; echo''.$cur_row.'<br/>'; echo'<div class="postbox"><h4>'.$row[1].'['.$row[2].']</h4><hr />' .$row[0]. '<br /><hr />[<a href="http://prime.programming-designs.com/test_forum/viewthread.php?thread='.$row[3].'">Reply</a>] '.$post_num.' posts omitted.</div>'; }

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  • MySQL "NULL" questions

    - by Camran
    I have a table with several columns. Sometimes some of these column fields may be empty (ie. I won't use them in some cases). My questions: Would it be smart to set them to NULL in phpmyadmin? What does the "NULL" property actually do? Would I gain anything at all by setting them to NULL? Is it possible to use a NULL field the same way even though it is set to null?

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  • join codition in sqlserver

    - by Pallavi
    after applying join condition on two tables i want records which is maximum among records of left table my query SELECT a1.*, t.*, ( a1.trnratefrom - t.trnratefrom )AS minrate, ( a1.trnrateto - t.trnrateto ) AS maxrate FROM (SELECT a.srno, trndate, b.trnsrno, Upper(Rtrim(Ltrim(b.trnstate))) AS trnstate, Upper(Rtrim(Ltrim(b.trnarea))) AS trnarea, Upper(Rtrim(Ltrim(b.trnquality))) AS trnquality, Upper(Rtrim(Ltrim(b.trnlength))) AS trnlength, Upper(Rtrim(Ltrim(b.trnunit))) AS trnunit, b.trnratefrom, b.trnrateto, a.remark, entdate FROM mstprodrates a INNER JOIN trnprodrates b ON a.srno = b.srno)a1 INNER JOIN (SELECT c.srno, trndate, d.trnsrno, Upper(Rtrim(Ltrim(d.trnstate))) AS trnstate, Upper(Rtrim(Ltrim(d.trnarea))) AS trnarea, Upper(Rtrim(Ltrim(d.trnquality))) AS trnquality, Upper(Rtrim(Ltrim(d.trnlength))) AS trnlength, Upper(Rtrim(Ltrim(d.trnunit))) AS trnunit, d.trnratefrom, d.trnrateto, c.remark, entdate FROM mstprodrates c INNER JOIN trnprodrates d ON c.srno = d.srno) AS t ON a1.trnstate = t.trnstate AND a1.trnquality = t.trnquality AND a1.trnunit = t.trnunit AND a1.trnlength = t.trnlength AND a1.trnarea = t.trnarea AND a1.remark = t.remark WHERE t.srno = (SELECT MAX(srno) FROM a1 WHERE srno < a1.srno)

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  • How do you write a recursive stored procedure

    - by Grayson Mitchell
    I simply want a stored procedure that calculates a unique id and inserts it. If it fails it just calls itself to regenerate said id. I have been looking for an example, but cant find one, and am not sure how I should get the sp to call itself, and set the appropriate output parameter. I would also appreciate someone pointing out how to test this sp also. ALTER PROCEDURE [dbo].[DataContainer_Insert] @SomeData varchar(max), @DataContainerId int out AS BEGIN -- SET NOCOUNT ON added to prevent extra result sets from -- interfering with SELECT statements. SET NOCOUNT ON; BEGIN TRY SELECT @UserId = MAX(UserId) From DataContainer INSERT INTO DataContainer (UserId, SomeData) VALUES (@UserId, SomeData) SELECT @DataContainerId = scope_identity() END TRY BEGIN CATCH --try again exec DataContainer_Insert @DataContainerId, @SomeData END CATCH END

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  • MySQL subquery and bracketing

    - by text
    Here are my tables respondents: field sample value respondentid : 1 age : 2 gender : male survey_questions: id : 1 question : Q1 answer : sample answer answers: respondentid : 1 question : Q1 answer : 1 --id of survey question I want to display all respondents who answered the certain survey, display all answers and total all the answer and group them according to the age bracket. I tried using this query: SELECT res.Age, res.Gender, answer.id, answer.respondentid, SUM(CASE WHEN res.Gender='Male' THEN 1 else 0 END) AS males, SUM(CASE WHEN res.Gender='Female' THEN 1 else 0 END) AS females, CASE WHEN res.Age < 1 THEN 'age1' WHEN res.Age BETWEEN 1 AND 4 THEN 'age2' WHEN res.Age BETWEEN 4 AND 9 THEN 'age3' WHEN res.Age BETWEEN 10 AND 14 THEN 'age4' WHEN res.Age BETWEEN 15 AND 19 THEN 'age5' WHEN res.Age BETWEEN 20 AND 29 THEN 'age6' WHEN res.Age BETWEEN 30 AND 39 THEN 'age7' WHEN res.Age BETWEEN 40 AND 49 THEN 'age8' ELSE 'age9' END AS ageband FROM Respondents AS res INNER JOIN Answers as answer ON answer.respondentid=res.respondentid INNER JOIN Questions as question ON answer.Answer=question.id WHERE answer.Question='Q1' GROUP BY ageband ORDER BY res.Age ASC I was able to get the data but the listing of all answers are not present. Do I have to subquery SELECT into my current SELECT statement to show the answers? I want to produce something like this: ex: # of Respondents is 3 ages: 2,3 and 6 Question: what are your favorite subjects? Ages 1-4: subject 1: 1 subject 2: 2 subject 3: 2 total respondents for ages 1-4 : 2 Ages 5-10: subject 1: 1 subject 2: 1 subject 3: 0 total respondents for ages 5-10 : 1

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