Feb 2, 2008
Hi, Please help me with an SQL Query that fetches all the records from the three tables but a unique record for each forum and topicid with the maximum lastpostdate. Please provide separate solutions for SqlServer2000/2005.
I have four tables namely – Forums,Topics,Threads and Messages in SQL Server2000 (scripts for table creation and insertion of test data given at the end). Now, I have formulated a query as below :-
SELECT Forums.forumid AS ForumID,Topics.topicid AS TopicID,Topics.name AS TopicName,LastPosts.date as LastPostDate,LastPosts.author AS Author,
(select count(threadid) from Threads where Threads.topicid=Topics.topicid) as NoOfThreads
FROM Forums JOIN Topics ON Forums.forumid=Topics.forumid
LEFT OUTER JOIN
(
SELECT Topics.forumid,Threads.topicid,Messages.date,Messages.author FROM Topics
INNER JOIN Threads ON Topics.topicid = Threads.topicid
INNER JOIN Messages ON Threads.threadid=Messages.threadid
WHERE Messages.date=(SELECT MAX(date) FROM Messages WHERE Messages.threadid = Threads.threadid)
) as LastPosts
ON LastPosts.forumid = Topics.forumid AND LastPosts.topicid = Topics.topicid
Whose result set is as below:-
forumid
topicid
name
LastPostDate
author
NoOfThreads
1
1
Java Overall
2008-02-02 13:06:06.267
l@m.com
2
1
1
Java Overall
2008-01-27 14:46:41.000
c@b.com
2
1
2
JSP
NULL
NULL
0
1
3
EJB
NULL
NULL
0
1
4
Swings
2008-01-27 15:12:51.000
p@q.com
1
1
5
AWT
NULL
NULL
0
1
6
Web Services
NULL
NULL
0
1
7
JMS
NULL
NULL
0
1
8
XML,HTML
NULL
NULL
0
1
9
Javascript
NULL
NULL
0
2
10
Oracle
NULL
NULL
0
2
11
Sql Server
NULL
NULL
0
2
12
MySQL
NULL
NULL
0
3
13
CSS
NULL
NULL
0
3
14
FLASH/DHTLML
NULL
NULL
0
4
15
Best Practices
NULL
NULL
0
4
16
Longue
NULL
NULL
0
5
17
General
NULL
NULL
0
I want the result set as follows:-
forumid
topicid
name
LastPostDate
author
NoOfThreads
1
1
Java Overall
2008-02-02 13:06:06.267
l@m.com
2
1
2
JSP
NULL
NULL
0
1
3
EJB
NULL
NULL
0
1
4
Swings
2008-01-27 15:12:51.000
p@q.com
1
1
5
AWT
NULL
NULL
0
1
6
Web Services
NULL
NULL
0
1
7
JMS
NULL
NULL
0
1
8
XML,HTML
NULL
NULL
0
1
9
Javascript
NULL
NULL
0
2
10
Oracle
NULL
NULL
0
2
11
Sql Server
NULL
NULL
0
2
12
MySQL
NULL
NULL
0
3
13
CSS
NULL
NULL
0
3
14
FLASH/DHTLML
NULL
NULL
0
4
15
Best Practices
NULL
NULL
0
4
16
Longue
NULL
NULL
0
5
17
General
NULL
NULL
0 I want all the rows from the Forums,Topics and Threads table and the row with the maximum date (the last post date of the message) from the Messages table as shown above.
When I use the query by using only three tables namely Forums,Topics and Threads, I get the correct result. The query is as:-
SELECT Topics.forumid AS ForumID,Forums.name AS ForumName,Topics.topicid as TopicID,Topics.name as TopicName,
LastPosts.author AS Author,LastPosts.lastpostdate AS LastPost,
(select count(threadid) from threads where Threads.topicid=Topics.topicid) as NoOfThreads
FROM Forums JOIN Topics ON Forums.forumid=Topics.forumid LEFT OUTER JOIN (
SELECT Topics.forumid, Threads.topicid, Threads.lastpostdate, Threads.author FROM Threads
INNER JOIN Topics ON Topics.topicid = Threads.topicid
WHERE Threads.lastpostdate IN (SELECT MAX(lastpostdate) FROM threads WHERE Topics.topicid = Threads.topicid)
) AS LastPosts
ON LastPosts.forumid = Topics.forumid AND LastPosts.topicid = Topics.topicid
Whose result set is as:-
ForumID
ForumName
TopicID
TopicName
Author
LastPost
NoOfThreads
1
Developers
1
Java Overall
x@y.com
2008-01-27 14:48:53.000
2
1
Developers
2
JSP
NULL
NULL
0
1
Developers
3
EJB
NULL
NULL
0
1
Developers
4
Swings
p@q.com
2008-01-27 15:12:51.000
1
1
Developers
5
AWT
NULL
NULL
0
1
Developers
6
Web Services
NULL
NULL
0
1
Developers
7
JMS
NULL
NULL
0
1
Developers
8
XML,HTML
NULL
NULL
0
1
Developers
9
Javascript
NULL
NULL
0
2
Database
10
Oracle
NULL
NULL
0
2
Database
11
Sql Server
NULL
NULL
0
2
Database
12
MySQL
NULL
NULL
0
3
Desginers
13
CSS
NULL
NULL
0
3
Desginers
14
FLASH/DHTLML
NULL
NULL
0
4
Architects
15
Best Practices
NULL
NULL
0
4
Architects
16
Longue
NULL
NULL
0
5
General
17
General
NULL
NULL
0
The scripts for creating the tables and inserting test data is as follows in an already created database:-
if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[FK__Topics__forumid__35BCFE0A]') and OBJECTPROPERTY(id, N'IsForeignKey') = 1)
ALTER TABLE [dbo].[Topics] DROP CONSTRAINT FK__Topics__forumid__35BCFE0A
GO
if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[FK__Threads__topicid__34C8D9D1]') and OBJECTPROPERTY(id, N'IsForeignKey') = 1)
ALTER TABLE [dbo].[Threads] DROP CONSTRAINT FK__Threads__topicid__34C8D9D1
GO
if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[FK__Messages__thread__33D4B598]') and OBJECTPROPERTY(id, N'IsForeignKey') = 1)
ALTER TABLE [dbo].[Messages] DROP CONSTRAINT FK__Messages__thread__33D4B598
GO
if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[Forums]') and OBJECTPROPERTY(id, N'IsUserTable') = 1)
drop table [dbo].[Forums]
GO
if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[Topics]') and OBJECTPROPERTY(id, N'IsUserTable') = 1)
drop table [dbo].[Topics]
GO
if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[Threads]') and OBJECTPROPERTY(id, N'IsUserTable') = 1)
drop table [dbo].[Threads]
GO
if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[Messages]') and OBJECTPROPERTY(id, N'IsUserTable') = 1)
drop table [dbo].[Messages]
GO
CREATE TABLE [dbo].[Forums] (
[forumid] [int] IDENTITY (1, 1) NOT NULL ,
[name] [varchar] (255) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL ,
[description] [varchar] (255) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL
) ON [PRIMARY]
GO
CREATE TABLE [dbo].[Topics] (
[topicid] [int] IDENTITY (1, 1) NOT NULL ,
[forumid] [int] NULL ,
[name] [varchar] (255) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL ,
[description] [varchar] (255) COLLATE SQL_Latin1_General_CP1_CI_AS NULL
) ON [PRIMARY]
GO
CREATE TABLE [dbo].[Threads] (
[threadid] [int] IDENTITY (1, 1) NOT NULL ,
[topicid] [int] NOT NULL ,
[subject] [varchar] (100) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL ,
[replies] [int] NOT NULL ,
[author] [varchar] (100) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL ,
[lastpostdate] [datetime] NULL
) ON [PRIMARY]
GO
CREATE TABLE [dbo].[Messages] (
[msgid] [int] IDENTITY (1, 1) NOT NULL ,
[threadid] [int] NOT NULL ,
[author] [varchar] (100) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL ,
[date] [datetime] NULL ,
[message] [text] COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL
) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]
GO
ALTER TABLE [dbo].[Forums] ADD
PRIMARY KEY CLUSTERED
(
[forumid]
) ON [PRIMARY]
GO
ALTER TABLE [dbo].[Topics] ADD
PRIMARY KEY CLUSTERED
(
[topicid]
) ON [PRIMARY]
GO
ALTER TABLE [dbo].[Threads] ADD
PRIMARY KEY CLUSTERED
(
[threadid]
) ON [PRIMARY]
GO
ALTER TABLE [dbo].[Messages] ADD
PRIMARY KEY CLUSTERED
(
[msgid]
) ON [PRIMARY]
GO
ALTER TABLE [dbo].[Topics] ADD
FOREIGN KEY
(
[forumid]
) REFERENCES [dbo].[Forums] (
[forumid]
)
GO
ALTER TABLE [dbo].[Threads] ADD
FOREIGN KEY
(
[topicid]
) REFERENCES [dbo].[Topics] (
[topicid]
)
GO
ALTER TABLE [dbo].[Messages] ADD
FOREIGN KEY
(
[threadid]
) REFERENCES [dbo].[Threads] (
[threadid]
)
GO
------------------------------------------------------
insert into forums(name,description) values('Developers','Developers Forum');
insert into forums(name,description) values('Database','Database Forum');
insert into forums(name,description) values('Desginers','Designers Forum');
insert into forums(name,description) values('Architects','Architects Forum');
insert into forums(name,description) values('General','General Forum');
insert into topics(forumid,name,description) values(1,'Java Overall','Topic Java Overall');
insert into topics(forumid,name,description) values(1,'JSP','Topic JSP');
insert into topics(forumid,name,description) values(1,'EJB','Topic Enterprise Java Beans');
insert into topics(forumid,name,description) values(1,'Swings','Topic Swings');
insert into topics(forumid,name,description) values(1,'AWT','Topic AWT');
insert into topics(forumid,name,description) values(1,'Web Services','Topic Web Services');
insert into topics(forumid,name,description) values(1,'JMS','Topic JMS');
insert into topics(forumid,name,description) values(1,'XML,HTML','XML/HTML');
insert into topics(forumid,name,description) values(1,'Javascript','Javascript');
insert into topics(forumid,name,description) values(2,'Oracle','Topic Oracle');
insert into topics(forumid,name,description) values(2,'Sql Server','Sql Server');
insert into topics(forumid,name,description) values(2,'MySQL','Topic MySQL');
insert into topics(forumid,name,description) values(3,'CSS','Topic CSS');
insert into topics(forumid,name,description) values(3,'FLASH/DHTLML','Topic FLASH/DHTLML');
insert into topics(forumid,name,description) values(4,'Best Practices','Best Practices');
insert into topics(forumid,name,description) values(4,'Longue','Longue');
insert into topics(forumid,name,description) values(5,'General','General Discussion');
insert into threads(topicid,subject,replies,author,lastpostdate) values (1,'About Java Tutorial',2,'a@b.com','1/27/2008 02:44:29 PM');
insert into threads(topicid,subject,replies,author,lastpostdate) values (1,'Java Basics',0,'x@y.com','1/27/2008 02:48:53 PM');
insert into threads(topicid,subject,replies,author,lastpostdate) values (4,'Swings',0,'p@q.com','1/27/2008 03:12:51 PM');
insert into messages(threadid,author,date,message) values(1,'a@b.com','1/27/2008 2:44:39 PM','Where can I find Java tutorials.');
insert into messages(threadid,author,date,message) values(1,'c@d.com','1/27/2008 2:45:28 PM','Please visit www.java.sun.com');
insert into messages(threadid,author,date,message) values(1,'c@d.com','1/27/2008 2:46:41 PM','Do a Google serach for more tutorials.');
insert into messages(threadid,author,date,message) values(2,'x@y.com','1/27/2008 2:48:53 PM','Please provide some Beginner tutorials.');
insert into messages(threadid,author,date,message) values(3,'p@q.com','1/27/2008 3:12:51 PM','How many finds of layout managers are there?');
insert into messages(threadid,author,date,message) values(2,'l@m.com','2/2/2008 1:06:06 PM','Search on Google.');
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Jul 27, 2006
I've created a sproc that will provide a recordset for an Access report via a pass-thru query. The report is a production schedule.
Some of the runs on the schedule have a note associated with them. I need
to be able to number these notes, so that they can be displayed in the report
bibliography style. When I populate the data in the sproc, if the "notes"
field in my table contains any data I display a 1, else it's a 0
Like:
SELECT NOTE_FLAG = CASE WHEN ISNULL(SCHED_NOTE,'')<>'',1,0
FROM MASTER_SCHEDULE
The problem is, I really need to display sequential numbers instead of 1's
If I create a base set with this:
CREATE TABLE #TMPRST (
RECID INTEGER,
PRODUCT VARCHAR(10),
QTY FLOAT,
NOTE_FLAG INTEGER)
INSERT INTO #TMPRST
SELECT 1, 'ABC123', 4, 0
UNION ALL
SELECT 4, 'DEF123', 5, 1
UNION ALL
SELECT 5, 'ABC456', 12, 0
UNION ALL
SELECT 13, 'PQR789', 10, 1
How do I go back and convert the note_flag column to read
... 0
... 1
... 0
... 2
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