Hi,Would like to know the performance differenece between Multi-columnIndex vs Single Column Indexes. Let's say I have a table with col1,col2, col3 along with a primary key column and non-indexed columns.In queries, I will use col1, col2, and col3 together and some timesjust one or two of these three columns. My questions is, should Icreate one index contains col1, col2, and col3, or create 3 seperatedcolumns. I.e. each column has its own index. Any performancedifference?Thanks a lot.
I think I need to only create few if an index is covering all columns then I do not need to create more indexes for separate columns or should I create separate index as suggested?
Similarly:
CREATE INDEX [NCIX_20187_20186_TL_SRV_Stationary_Stock_Transact] ON [TL_SRV_Stationary_Stock_Transaction] ([SerialNo],[StationaryStatus]) GO CREATE INDEX [NCIX_20189_20188_TL_SRV_Stationary_Stock_Transact] ON [TL_SRV_Stationary_Stock_Transaction] ([StationaryStatus]) INCLUDE ([SerialNo]) GO
[Code] ....
Should I create all indexes above or use minimum number of indexes which covers all columns as mentioned in above create index statements?
I have created a single FULLTEXT on col2 & col3. suppose i want to search col2='engine' and col3='toyota' i write query as
SELECT
TBL.col2,TBL.col3 FROM
TBL INNER JOIN
CONTAINSTABLE(TBL,col2,'engine') TBL1 ON
TBL.col1=TBL1.[key] INNER JOIN
CONTAINSTABLE(TBL,col3,'toyota') TBL2 ON
TBL.col1=TBL2.[key]
Every thing works well if database is small. But now i have 20 million records in my database. Taking an exmaple there are 5million record with col2='engine' and only 1 record with col3='toyota', it take substantial time to find 1 record.
I was thinking this i can address this issue if i merge both columns in a Single column, but i cannot figure out what format i save it in single column that i can use query to extract correct information. for e.g.; i was thinking to concatinate both fields like col4= ABengineBA + ABBToyotaBBA and in search i use SELECT
TBL.col4 FROM
TBL INNER JOIN
CONTAINSTABLE(TBL,col4,' "ABengineBA" AND "ABBToyotaBBA"') TBL1 ON
TBL.col1=TBL1.[key] Result = 1 row
But it don't work in following scenario col4= ABengineBA + ABBCorola ToyotaBBA
SELECT
TBL.col4 FROM
TBL INNER JOIN
CONTAINSTABLE(TBL,col4,' "ABengineBA" AND "ABB*ToyotaBBA"') TBL1 ON
TBL.col1=TBL1.[key]
Result=0 Row Any idea how i can write second query to get result?
Suppose that I have a table with following values Table1 Col1 Col2 Col3 ----------------------------------------------------------- P3456 C935876 T675 P5555 C678909 T8888
And the outcome that I want is: CombinedValues(ColumnName) ---------------------------------------------- P3456 - C935876 - T675 P5555 - C678909 - T8888
where CombinedValues column contains values of coulmn 1,2 & 3 seperated by '-' So is there any way to achieve this?
I have a description field in a table which also stores unit of measure in the same column but with some space between them, I need to split these into two different columns.
I'm working on a script to merge multiple columns(30) into a single column separated by a semicolons, but I'm getting the following error below. I tried to convert to the correct value. but I'm still getting an error.
Error: "Conversion failed when converting the varchar value ';' to data type tinyint".
I have a database where records are Inserted by an external process. There is no updating or deleting of the data once inserted. The table in question has a Clustered Index on the Machine_ID (integer) (data is from manufacturing processes). Each record bears a start and end time. Most queries involve the Machine, a time span (start time between to points in time), the Downtime Cause, and the Running Mode.
I want to add an index on the Start Time, the Downtime Cause, and the Runtime Mode.
My question is: should this new index also contain the Machine_id column or does the existence of the Clustered Index already on that column negate its need in the new index?
RC - Dedicated to only creating original mistakes!
I've been asked to look at using Clustered Columnstore indexes for one of my tables. The table contains about 5 million records with about 50 columns. The max field size is a NVarchar(MAX) with max field length currently of about 4k characters. It's only about a gigabyte's worth of data. The table is about 50% R/W operations. Currently, we have multiple indexes with no clustered index due to some performance issues that happened in the past. I've been attempting to determine if it's even really worth it to switch over. I feel that the table is still fairly small with minimal columns and don't believe there will be any noticeable improvement over traditional indexing.
Hi. I want to return multiple rows into a single row in different columns. For example my query returns something like thisThe query looks like thisSelect ID, TYPE, VALUE From myTable Where filtercondition = 1ID TYPE VALUE1 type1 121 type2 152 type1 16 2 type2 19Each ID will have the same number of types and each type for each ID might have a different value. So if there are only two types then each ID will have two types. Now I want to write the query in such a way that it returnsID TYPE1 TYPE2 VALUE1 VALUE21 type1 type2 12 152 type1 type2 16 19Type1, Type2, Value1, and Value2 are all dynamic. Can someone help me please. Thank you.
I have a one to many relationship between Flag and StudentFlag. I'm wanting to select each Flag.FlagID that exist as a column that contains the StudentFlag.Value per StudentFlag.StudentID (or null for that column if that StudentFlag row doesn't exist).
This single column appearing multple times in a single dataset has seemed difficult in a select statement. Is it posible in T-SQL?
Tables, Keys, and Relationships
CREATE TABLE [dbo].[Flag] ( [FlagID] [int] NOT NULL , [FlagName] [varchar] (50) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL ) ON [PRIMARY] GO
CREATE TABLE [dbo].[StudentFlag] ( [StudentFlagID] [int] NOT NULL , [FlagID] [int] NULL , [StudentID] [int] NOT NULL , [FlagValue] [varchar] (50) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL ) ON [PRIMARY] GO
ALTER TABLE [dbo].[Flag] WITH NOCHECK ADD CONSTRAINT [PK_Flag] PRIMARY KEY CLUSTERED ( [FlagID] ) ON [PRIMARY] GO
ALTER TABLE [dbo].[StudentFlag] WITH NOCHECK ADD CONSTRAINT [PK_StudentFlag] PRIMARY KEY CLUSTERED ( [StudentFlagID] ) ON [PRIMARY] GO
ALTER TABLE [dbo].[StudentFlag] ADD CONSTRAINT [FK_StudentFlag_Flag] FOREIGN KEY ( [FlagID] ) REFERENCES [dbo].[Flag] ( [FlagID] ) GO
My code below creates a trigger that fires whenever a change occurs to a 'myTable' row, but this is not what I want. I only want to log changes made to a single field called 'Charges', when that field is changed I want to log it, can anyone tell me how to modify my code to do this, thanks
Create Trigger dbo.myTrigger ON dbo.[myTable] FOR UPDATE AS Declare @now DATETIME Set @now = getdate()
BEGIN TRY Insert INTO dbo.myAuditTable (RowImage,Charges,ChangeDate,ChangeUser) SELECT 'BEFORE',Charges,@now, suser_sname() FROM DELETED Insert INTO dbo.myAuditTable (RowImage,Charges,ChangeDate,ChangeUser) SELECT 'AFTER',Charges,@now, suser_sname() FROM INSERTED END TRY
SELECT 'Type'[Type] ,CASE WHEN code='09' THEN SUM(Amt/100) ELSE 0 END ,CASE WHEN code='10' THEN SUM(Amt/100) ELSE 0 END ,CASE WHEN code='11' THEN SUM(Amt/100) ELSE 0 END ,CASE WHEN code='12' THEN SUM(Amt/100) ELSE 0 END FROM Table1 WHERE (Code BETWEEN '09' AND '12') GROUP BY Code
and the output
Column 1 Column 2 Column 3 Column 4 Type 14022731.60 0.00 0.00 0.00 Type 0.00 4749072.19 0.00 0.00 Type 0.00 0.00 149214.04 0.00 Type 0.00 0.00 0.00 792210.10
How can I modify the query to come up with output below,
ALTER TABLE [Students] WITH CHECK ADD CONSTRAINT [FK_Students_Schools] FOREIGN KEY([SchoolId]) REFERENCES [Schools] ([SchoolId])
What kind of index would ensure best performance for INSERTs/UPDATEs, so that SQL Server can most efficiently check the FK constraints? Would it be simply:
CREATE INDEX IX_Students_SchlId ON Students (SchoolId) Or CREATE INDEX IX_Students_SchlId ON Students (SchoolId, StudentId)
In other words, what's best practice for adding an index which best supports a Foreign Key constraint?
Hello, I will explain myself further. I want to make my table in such a way that no two colums have the same value for example: Row 1 - Column 1 = "cool" Row 1 - Column 3 = 91 Row 3 - Column 1 = "cool" Row 3 - Column 3 = 91
I dont care about one column having duplicate values, I want to protect against Column 1 and 3 having the same values on other rows. Is this possible to do in sql server?
I have multiple databases in the server and all my databases have tables: stdVersions, stdChangeLog. The stdVersions table have field called DatabaseVersion which stored the version of the database. The stdChangeLog table have a field called ChangedOn which stored the date of any change made in the database.
I need to write a query/stored procedure/function that will return all the database names, version and the date changed on. The results should look something like this:
I'm working to improve performance on a database I've inherited, and there are several thousand indexes. I've got a list of ones which should definitely exist within the database, and I'm looking to strip out all the others and start fresh, though this list is still quite large (1000 or so).
Is there a way I can remove all the indexes that are not in my list without too much trouble? I.e. without having to manually go through them all individually. The list is currently in a csv file.
I'm looking to either automate the removal of indexes not in the list, or possibly to generate the Create statements for the indexes on the list and simply remove all indexes and then run these statements.
As an aside, when trying to list all indexes in the database, I've found various scripts to do this, but found they all seem to produce differing results. What is the best script to list all indexes?
I’m trying to figure out a way to sum columns for similar IDs, based on the contents of a single field. For example, if I’m calculating attendance percentages for students, and codes P and T count as Present, and codes A and E count as Absent, I would want to total Present and Absent codes separately, in their own columns. I would then like to use those totals to calculate percentage, but I can do that. It’s the SUM based on column value (by ID) that is giving issue.
I’ve been playing around with nested queries, but nothing’s working. This is a glimpse of the mess that I’ve created trying to sort this out. Many errors.
I just noticed that I used a simpler example than the SQL I included, so I modified it a bit. There are additional fields that I'll need to include, but I want to get the logic working correctly. From there, I can handle the rest. So here's a more appropriate code example showing the direction I'm trying to go with this.
SELECT ID, [Last Name], [First Name], CD, Present, Absent, CAST(LEFT(Present / (Absent + Present) * 100, 5) AS varchar) + '%' AS Percentage FROM (SELECT ID, CD, TotalAHD, CAST ((SELECT SUM(TotalAHD) AS Expr1 FROM SumAHDforAttndPercentages AS p
I have 5 million rows of table, and going to create Non Clustered Index for Datetime values column. Creating Non clustered Index on Datetime value column will affect performance or not.
I have a data flow task in which there is a OLEDB source, derived column item, and a oledb destination. My source is a SQL command, that returns some values. I have some values, that I define in the derived columns, and set default values under the expression column. My question is, I also have some destination columns which in my OLEDB destination need another SQL command. How would I do that? Can I attach two or more OLEDB sources to one destination? How would I accomplish that? Thanks
Hi This is probably a very basic question for most people in this group. How do i split the data in a column in to 2 columns? This can be done in access with an update query but in MS SQL server I am not sure. Here is an example of what i want to acheive