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  • Specify sorting order for a GROUP BY query to retrieve oldest or newest record for each group

    - by Beau Simensen
    I need to get the most recent record for each device from an upgrade request log table. A device is unique based on a combination of its hardware ID and its MAC address. I have been attempting to do this with GROUP BY but I am not convinced this is safe since it looks like it may be simply returning the "top record" (whatever SQLite or MySQL thinks that is). I had hoped that this "top record" could be hinted at by way of ORDER BY but that does not seem to be having any impact as both of the following queries returns the same records for each device, just in opposite order: SELECT extHwId, mac, created FROM upgradeRequest GROUP BY extHwId, mac ORDER BY created DESC SELECT extHwId, mac, created FROM upgradeRequest GROUP BY extHwId, mac ORDER BY created ASC Is there another way to accomplish this? I've seen several somewhat related posts that have all involved sub selects. If possible, I would like to do this without subselects as I would like to learn how to do this without that.

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  • Database design advice needed.

    - by user346271
    Hi all, I'm a lone developer for a telecoms company, and am after some database design advice from anyone with a bit of time to answer. I am inserting into one table ~2 million rows each day, these tables then get archived and compressed on a monthly basis. Each monthly table contains ~15,000,000 rows. Although this is increasing month on month. For every insert I do above I am combining the data from rows which belong together and creating another "correlated" table. This table is currently not being archived, as I need to make sure I never miss an update to the correlated table. (Hope that makes sense) Although in general this information should remain fairly static after a couple of days of processing. All of the above is working perfectly. However my company now wishes to perform some stats against this data, and these tables are getting too large to provide the results in what would be deemed a reasonable time. Even with the appropriate indexes set. So I guess after all the above my question is quite simple. Should I write a script which groups the data from my correlated table into smaller tables. Or should I store the queries result sets in something like memcache? I'm already using mysqls cache, but due to having limited control over how long the data is stored for, it's not working ideally. The main advantages I can see of using something like memcache: No blocking on my correlated table after the query has been cashed. Greater flexibility of sharing the collected data between the backend collector and front end processor. (i.e custom reports could be written in the backend and the results of these stored in the cache under a key which then gets shared with anyone who would want to see the data of this report) Redundancy and scalability if we start sharing this data with a large amount of customers. The main disadvantages I can see of using something like memcache: Data is not persistent if machine is rebooted / cache is flushed. The main advantages of using MySql Persistent data. Less code changes (although adding something like memcache is trivial anyway) The main disadvantages of using MySql Have to define table templates every time I want to store provide a new set of grouped data. Have to write a program which loops through the correlated data and fills these new tables. Potentially will still grow slower as the data continues to be filled. Apologies for quite a long question. It's helped me to write down these thoughts here anyway, and any advice/help/experience with dealing with this sort of problem would be greatly appreciated. Many thanks. Alan

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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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  • MySQL: Limit rows linked to each joined row

    - by SolidSnakeGTI
    Hello, Specifications: MySQL 4.1+ I've certain situation that requires certain result set from MySQL query, let's see the current query first & then ask my question: SELECT thread.dateline AS tdateline, post.dateline AS pdateline, MIN(post.dateline) FROM thread AS thread LEFT JOIN post AS post ON(thread.threadid = post.threadid) LEFT JOIN forum AS forum ON(thread.forumid = forum.forumid) WHERE post.postid != thread.firstpostid AND thread.open = 1 AND thread.visible = 1 AND thread.replycount >= 1 AND post.visible = 1 AND (forum.options & 1) AND (forum.options & 2) AND (forum.options & 4) AND forum.forumid IN(1,2,3) GROUP BY post.threadid ORDER BY tdateline DESC, pdateline ASC As you can see, mainly I need to select dateline of threads from 'thread' table, in addition to dateline of the second post of each thread, that's all under the conditions you see in the WHERE CLAUSE. Since each thread has many posts, and I need only one result per thread, I've used GROUP BY CLAUSE for that purpose. This query will return only one post's dateline with it's related unique thread. My questions are: How to limit returned threads per each forum!? Suppose I need only 5 threads -as a maximum- to be returned for each forum declared in the WHERE CLAUSE 'forum.forumid IN(1,2,3)', how can this be achieved. Is there any recommendations for optimizing this query (of course after solving the first point)? Notes: I prefer not to use sub-queries, but if it's the only solution available I'll accept it. Double queries not recommended. I'm sure there's a smart solution for this situation. Appreciated advice in advance :)

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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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  • how to do multi insert and obtain ids

    - by liysd
    hi, I want to insert some data into a table (id PK autoincrement, val) with use multi insert INSERT INTO tab (val) VALUES (1), (2), (3) Is it possible to obtain a table of last inserted ids? I'm asking becouse I'm not sure if all will in this form: (n, n+1, n+2). I use mysql inodb.

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  • Minimum number of training examples for Find-S/Candidate Elimination algorithms?

    - by Rich
    Consider the instance space consisting of integer points in the x, y plane, where 0 = x, y = 10, and the set of hypotheses consisting of rectangles (i.e. being of the form (a = x = b, c = y = d), where 0 = a, b, c, d = 10). What is the smallest number of training examples one needs to provide so that the Find-S algorithm perfectly learns a particular target concept (e.g. (2 = x = 4, 6 = y = 9))? When can we say that the target concept is exactly learned in the case of the Find-S algorithm, and what is the optimal query strategy? I'd also like to know the answer w.r.t Candidate Elimination. Thanks in advance.

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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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  • Store latitudes and longitudes in database for proximity/radius search using Google Maps API, .NET a

    - by poojad
    What is the approach for storing the latitudes and longitudes for multiple addresses as a one time set up. I need to find the nearby stores using Google Maps and I have to get the latitudes and longitudes of all the available stores. As the data is huge and may increase or change in future, can anyone suggest an approach taking performance and maintenance into consideration. Thank you.

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  • Classic ASP shopping cart discounts

    - by Neil Bradley
    Hi there, I have a Classic ASP shopping cart, but I need to add in an option to enter a promo code and (if valid) apply a discount to the total. There is a promo codes table that stores the promotional codes and the value of the discount to apply. So I was wondering if someone might be able to help me integrate this? Happy to pay for the time. I think it may only take an hour or so at most. :S

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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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  • 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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  • 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 top 50 records from sql

    - by air
    i have following database table name tbl_rec recno uid uname points ============================ 1 a abc 10 2 b bac 8 3 c cvb 12 4 d aty 13 5 f cyu 9 ------------------------- ------------------------- i have about 5000 records in this table. i want to select first 50 higher points records. i can't use limit statement as i am already using limit for paging. Thanks

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  • MySQL Rating system (calculating average from two tables).

    - by MussuR
    I have two tables, videos and videos_ratings. The videos table has an int videoid field (and many others but those fields are not important I think) and many records. The videos_ratings table has 3 int fields: videoid, rating, rated_by which has many records (multiple records for each fields from the videos table) but not for all records from the videos table. Currently I have the following mysql query: SELECT `videos`.*, avg(`videos_ratings`.`vote`) FROM `videos`, `videos_ratings` WHERE `videos_ratings`.`videoid` = `videos`.`videoid` GROUP BY `videos_ratings`.`videoid` ORDER BY RAND() LIMIT 0, 12 It selects all the records from table videos that have a rating in table video_ratings and calculates the average correctly. But what I need is to select all records from the videos table, no matter if there is a rating for that record or not. And if there aren't any records in the videos_ratings table for that particular videos record, the average function should show 0. Hope someone could understand what I want... :) Thanks!

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  • Query to add a column depending of outcome of there columns

    - by Tam
    I have a user table 'users' that has fields like: id first_name last_name ... and have another table that determines relationships: user_id friend_id user_accepted friend_accepted .... I would like to generate a query that selects all the users but also add another field/column say 'network_status' that depends on the values of user_accepted and fiend_accepted. For example, if user_accepted is true friend_accepted is false I want the 'network_status' field to say 'request sent'. Can I possibly do this in one query? (I would prefer not to user if/else inside the query but if that's the only way so be it)

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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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  • help configuring a mail server for use with mail.jar and activation.jar

    - by bobbyblue
    im trying to work with the below code: import javax.servlet.*; import javax.servlet.http.*; import java.io.*; import javax.mail.*; import javax.mail.internet.*; // important import javax.mail.event.*; // important import java.net.*; import java.util.*; public class servletmail extends HttpServlet { public void doPost(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException { PrintWriter out=response.getWriter(); response.setContentType("text/html"); try { Properties props=new Properties(); props.put("mail.smtp.host","localhost"); // 'localhost' for testing Session session1 = Session.getDefaultInstance(props,null); String s1 = request.getParameter("text1"); //sender (from) String s2 = request.getParameter("text2"); String s3 = request.getParameter("text3"); String s4 = request.getParameter("area1"); Message message =new MimeMessage(session1); message.setFrom(new InternetAddress(s1)); message.setRecipients (Message.RecipientType.TO,InternetAddress.parse(s2,false)); message.setSubject(s3); message.setText(s4); Transport.send(message); out.println("mail has been sent"); } catch(Exception ex) { System.out.println("ERROR....."+ex); } } } im using mail.jar and activation.jar but i cant understand how shouls i configure it with a mail server which mail server should i use will i be able to send an email using above what are the requirements a mail server? how should i configure it

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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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  • Specify fields in a recursive find with cakephp

    - by Razor Storm
    Suppose I have a table Recipe that hasmany ingredients. I do a recursive find to grab recipes with their associated ingredients: $this->Recipe->find('all', array('fields' => array('id','title','description'))); Here I can use the 'fields' attribute to specify that I only want it to return id, title, and description. However, despite this, cakephp still returns ALL columns from the ingredients table. How do I tell cakephp that I only want ingredient table's id and name fields? btw ingredient model is "Ingredient" and the table is ingredients, and the aggregation table is recipes_ingredients.

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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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