Does column order really matter for Query Optimizer to pick index.
Case 1:
Say my CUSTOMER table has one composite index containing FirstName and LastName. FirstName exists prior than LastName. Does the column, FirstName and LastName, order matter to have Query Optimizer to utilize the index when I write WHERE clause in a SELECT statement?
Statement 1:
SELECT * FROM CUSTOMER
WHERE FirstName = 'John' and LastName ='Smith'
Statement 2:
SELECT * FROM CUSTOMER
WHERE LastName ='Smith' and FirstName = 'John'
Will both statement 1 and 2 use the composite index or only statement 1?
Case 2:
Say my CUSTOMER has two single-column indexes. One index is on column FirstName. Another is on column LastName.For statement 1 and 2 above, which index will be picked by Query Optimizer or both? How does QO pick for index?
I read couple book and some books say column order matter but some say no. Which one should I go with? I'm kind of confused.
Does column order matter when creating a table? For example, Should NOT NULL columns always come before NULL columns? Should most frequently used columns always be near the top? What about text, ntext and image data types? Should they always appear near the end of the column order?
Hi, We got a problem. supposing we have a table like this:
CREATE TABLE a ( aId int IDENTITY(1,1) NOT NULL, aName string2 NOT NULL ) go ALTER TABLE a ADD CONSTRAINT PK_a PRIMARY KEY CLUSTERED (aId) go
insert into a values ('bank of abcde'); insert into a values ('bank of abcde'); ... ... (20 times)
select top 5 * from a order by aName Result is: 6Bank of abcde 5Bank of abcde 4Bank of abcde 3Bank of abcde 2Bank of abcde
select top 10 * from a order by aName Result is: 11Bank of abcde 10Bank of abcde 9Bank of abcde 8Bank of abcde 7Bank of abcde 6Bank of abcde 5Bank of abcde 4Bank of abcde 3Bank of abcde 2Bank of abcde
According to this result, user see the first 5 records with id 6, 5, 4, 3, 2 in page 1, but when he tries to view page 2, he still see the records with id 6, 5, 4, 3, 2. This is not correct for users. :eek:
Of course we can add order by aid also, but there are tons of sqls like this, we can't update our application in one shot.
So I ask for your advice here, is there any settings can tell the db use default sort order when the order by column value are the same? Or is there any other solution to resolve this problem in one shot?
Hi, We got a problem. supposing we have a table like this:
CREATE TABLE a ( aId int IDENTITY(1,1) NOT NULL, aName string2 NOT NULL ) go ALTER TABLE a ADD CONSTRAINT PK_a PRIMARY KEY CLUSTERED (aId) go
insert into a values ('bank of abcde'); insert into a values ('bank of abcde'); ... ... (20 times)
select top 5 * from a order by aName Result is: 6 Bank of abcde 5 Bank of abcde 4 Bank of abcde 3 Bank of abcde 2 Bank of abcde
select top 10 * from a order by aName Result is: 11 Bank of abcde 10 Bank of abcde 9 Bank of abcde 8 Bank of abcde 7 Bank of abcde 6 Bank of abcde 5 Bank of abcde 4 Bank of abcde 3 Bank of abcde 2 Bank of abcde
According to this result, user see the first 5 records with id 6, 5, 4, 3, 2 in page 1, but when he tries to view page 2, he still see the records with id 6, 5, 4, 3, 2. This is not correct for users. Of course we can add order by aid also, but there are tons of sqls like this, we can't update our application in one shot. So I ask for your advice here, is there any settings can tell the db use default sort order when the order by column value are the same? Or is there any other solution to resolve this problem in one shot?
I'm setting up SQL Server 7.0 as follows: 12 Gb initial data load; heavy transaction OLTP; 4 processors; RAID5 disk space NOT an issue.
I'm trying to figure out what a reasonable initial size for both the Transaction Log and Tempdb should be. I was thinking 100Mb for each. Is this reasonable, or could either afford to have more?
Is there a percentage of the .mdf that is recognized as a general rule of thumb for setting up the Transaction Log and/or Tempdb?
Also, is there any value in assigning Filegroups in a RAID5 setup?
I've officially done everything. I've uninstalled everything I can think of. I've cleaned the registry until it sparkles. I've removed all directories having anything to do with VS or SQL. I've even run the uninstall tool multiple times and been told everything is OK. However, SQL Server Express STILL tells me there are "beta versions" of stuff on my machine. Do you have any suggestions, or should I just give up in disgust?!?!?!
I have a query that searches through a 4 million record table. The data is fed from the UNIX flat file systems so the data is not in optimal search format. So I created some views that massaged the data and then index them. I select and join the original table with the view, with NOEXPAND hint on the view. My question is this theory right: If I put the criteria in the FROM join part then it will make the join easier than if I put it in the where clause?
Example (any difference) SELECT stuff1, stuff2 FROM UglyData u INNER JOIN MassageTable m ON m.RecNumber LIKE '112%' AND u.ID = m.ID versus SELECT stuff1, stuff2 FROM UglyData u INNER JOIN MassageTable m ON u.ID = m.ID WHERE m.RecNumber LIKE '112%'
I have a question i need to ask. Since i'm new to SQL Server, i did a bit of experiment with SQL Server 2005 Express. I made up a simple Access Database file and migrated it to SQL Server. it was success which is good. Now i have a real Access Database file which i built for my client. Since he uses the SQL Server 2000 service pack 4, i was wondering if the version would matter a lot.
There are two fieldsA1 nvarchar(30)A2 nvarchar(800)I know nvarchar field is alterable length, if I store a string mystring='abc' to A1 field or to A2 field, I think they use the same disk space, so I think it's always a good way to define a big length nvarchar field such as A3 nvarchar(4000) for any length string, becuase they always use the same disk space, is it right?
I have two tables that I am trying to join and both have similar columns with which I am trying to use. One is Date and the other is LOGdate. Date's format is "01/01/2000" BUT LOGdate's is "01/01/2000 12:41:00 PM/AM". Can I join these two tables?
I have two tables that I am trying to join and both have similar columns with which I am trying to use. One is Date and the other is LOGdate. Date's format is "01/01/2000" BUT LOGdate's is "01/01/2000 12:41:00 PM/AM". Can I join these two tables? If yes how do I get rid of the excess time on LOGdate.
select b.isin, a.market, a.ccy, a.stock_mkt, max(a.year) ,max(a.month), max(a.day) from market_table a inner join isin_table b on a.id = b.id where a.isin_closing_date=0 and a.market in ('XFFA', 'XFFA') and b.isin_type= 'I' and b.isin = 'DEX' group by b.isin, a.market, a.ccy, a.stock_mkt
what's needed is to get the earliest record all times, no mater the currency :
I'm using SQL Server 2005 and are having some troubble with sorting a paged result set. I'm using the OVER Clause to achieve the sorting and paging and have the following query:1 WITH ProjectList AS 2 ( 3 SELECT 4 Id, 5 Name, 6 Created, 7 (SELECT COUNT(*) FROM UserProjects WHERE ProjectId = p.Id) AS NumberOfUsers, 8 ROW_NUMBER() OVER (ORDER BY Id) AS 'RowNumber' 9 FROM Projects p 10 ) 11 SELECT * 12 FROM ProjectList 13 WHERE RowNumber BETWEEN 50 AND 60;
This works fine, and give me the results i want. The problem occurs when I want to sort by "NumberOfUsers" which is the results of a sub query.When i say "ORDER BY NumberOfUsers" instead of Id on line 8, I get the following error: Msg 207, Level 16, State 1, Line 10Invalid column name 'NumberOfUsers'. I read this in the documentation: When used in the context of a ranking window function, <ORDER BY Clause> can only refer to columns made available by the FROM clause. An integer cannot be specified to represent the position of the name or alias of a column in the select list. <ORDER BY Clause> cannot be used with aggregate window functions. So this means that what I'm trying to do is not possible. How can I then sort by NumberOfUsers? Is there any other way to achieve this
I need to be able to pass a parameter to a stored procedure indicating which column to sort the outcome by. I cannot simply sort it by the passed variable (or I have the syntax wrong...). The sort can be anyone of eight columns and I need to do this in a fair few places on complex SELECT statements, so I am reluctant to use a case statement, which would make the sp rather large.
I have a SELECT statement in an SP that selects 10 fields, however, i want to be able to pass a variable to the SP to determine which field to ORDER BY.
Is there a way to do this ?
I've tried passing in one of the field names to a variable and then doing ORDER BY @OrderByThisColumn ...nope. I've tried SETting a variable to the above @OrderByThisColumn ...nope.
SELECT H.Fund_Man as Holders, H.Shares as SharesHeld, H.Share_Pric * H.Shares as Value, H.Pcent as SharesOutstanding, H.Shares - H.Shares as ShareChange, C.Reg_Date as ReportDate, 'Register' as Source, ((C.Capital / S.CapTotal) * (H.TotalTot * S.CapTotal)) / C.Capital as SectorWeightingPcent, H.Pcent - (((C.Capital / S.CapTotal) * (H.TotalTot * S.CapTotal)) / C.Capital) as OverUnderWeight, (H.Pcent - (((C.Capital / S.CapTotal) * (H.TotalTot * S.CapTotal)) / C.Capital)) * C.isc as SurplusDeficit
FROM Citywatch_Company C Inner Join Citywatch_Holders H On C.Epic = H.Epic Inner Join Citywatch_Sector S On H.Sector = S.Sec_Code WHERE C.Epic = @CompanyCode
Hi, I am writing a small search engine. There are two tables. The first one holds the search engine main index, the second one is link table. I have the following query that retrieves results. I would like to sort the results by: dbo.OCCURS2(LOWER(:query),se_links.anchor). se_links.anchor obviously comes from se_links table, so I get an error. Is it possible to done in one query? I'm using MSSQL 2005. Thanks. PS. Function OCCURS2 returns number of occurrences of one string in other.
Code:
select id as Id, uri as ElementUri, size as Size, modified_date as ModifiedDate, title as Title, text as Text, dbo.OCCURS2(LOWER(:query),Title) as TitleOcc, dbo.OCCURS2(LOWER(:query),Text) as BodyOcc FROM se_index WHERE (title LIKE :query) OR (text LIKE :query) OR (id IN (SELECT se_links.target_index_id FROM se_links INNER JOIN se_index AS se_index_1 ON se_links.target_index_id = se_index_1.id AND se_links.anchor LIKE :query))
Hello,Using SQL 2005. Columns:ID, int (PK, auto-increment by 1)WorkHours, intName, varchar(100)I can't seem to get the following query to work. I want to return allNames and the sum of ALL work hours, in each row and order by eachINDIVIDUAL work hour:SELECT Name, SUM(WorkHours) as hFROM EmployersORDER BY WorkHours DESCIt seems that putting WorkHours in but the aggregate function and theORDER BY clause creates a problem.Thank you for your help!
I have a table that I want to re-order the ID column. The ID are not in order now due to some insertion and deletion. What are the steps to re-order the ID column?
I would like to create a database that keeps track of our companies subject matter experts. I have roughed out some of the tables. I would appreciate any feedback on if this is the right approach and if there might be any issues when I start writting a front-end (probably VB 2005).
What makes this interesting (at least for me) is that a subject has an owner and at least 1 "expert", possibly up to 3. Here is what I am thinking for tables:
Hi,I created a composite index (lastname, firstname). I know the followingqueries will use this index:WHERE lastname = ...WHERE lastname = ... AND firstname = ...Also this won't use the index:WHERE firstname = ...But how about: WHERE firstname = .. AND lastname = ...And why?Thanks a lot,Baihao--Posted via Mailgate.ORG Server - http://www.Mailgate.ORG
This subject has been posted several times, but I haven't seen a goodanswer.Problem:I want to change the order of the columns in a table using T-SQL only.Explanation:After running your code, I want to see the following table...CREATE TABLE [dbo].[TableName] ([First_Column] [int] NULL ,[Second_Column] [varchar] (20) NULL) ON [PRIMARY]look like this...CREATE TABLE [dbo].[TableName] ([Second_Column] [varchar] (20) NULL ,[First_Column] [int] NULL) ON [PRIMARY]Limitations:Don't post if your post would fall in the following categories:1. If you don't think it can be done2. If you think Enterprise Manager is the only way to do this3. If you think I should just change the order of my Selectstatements4. If you want to state that order column doesn't matter in arelational database5. If you want to ask me why I want to do thisWish:Hopefully the answer WON'T involve creating a brand new table, movingthe data from old to new, dropping the old table, then renaming thenew table to the old name. Yes, I can do that. The table I'm workingwith is extremely huge -- I don't want to do the data juggling.Thanks in advance!
Is it possible to add a column to a table using the "alter table"statement and specify where in the sequence of columns the new columnsits. If not is there any way to alter the order of columns using TSQLrather than Enterprise Manager / Design Table.TIALaurence Breeze
I have two tables, one is called (questions), the second one (answers).
questions columns are (ID,questionTitle)
answers columns are (ID,questionID,answer, answerDate)
I use this query to load data: "SELECT q.questionTitle,COUNT (a.ID),a.answerDate FROM questions q LEFT JOIN answers a ON q.ID=a.questionID" the query is easy, but my problem which I can't solve is how can I fetch the data ordered by the column answerDate, I mean I want the first record to be the one which has the most recent answer and so on.
