Sunday, April 13, 2008
SET SHOWPLAN_TEXT
Remarks: The setting of SET SHOWPLAN_TEXT is set at execute or run time and not at parse time.
SET SHOWPLAN_TEXT ON
GO
USE pubs
SELECT * FROM roysched
WHERE title_id = 'PS1372'
GO
SET SHOWPLAN_TEXT OFF
GO
SQL Server script to rebuild all indexes for all tables and all databases
DECLARE @Database VARCHAR(255)
DECLARE @Table VARCHAR(255)
DECLARE @cmd NVARCHAR(500)
DECLARE @fillfactor INT
SET @fillfactor = 90
DECLARE DatabaseCursor CURSOR FOR
SELECT name FROM master.dbo.sysdatabases
WHERE name NOT IN ('master','model','msdb','tempdb','distrbution')
ORDER BY 1
OPEN DatabaseCursor
FETCH NEXT FROM DatabaseCursor INTO @Database
WHILE @@FETCH_STATUS = 0
BEGIN
SET @cmd = 'DECLARE TableCursor CURSOR FOR SELECT table_catalog + ''.'' + table_schema + ''.'' + table_name as tableName
FROM ' + @Database + '.INFORMATION_SCHEMA.TABLES WHERE table_type = ''BASE TABLE'''
-- create table cursor
EXEC (@cmd)
OPEN TableCursor
FETCH NEXT FROM TableCursor INTO @Table
WHILE @@FETCH_STATUS = 0
BEGIN
-- SQL 2000 command
--DBCC DBREINDEX(@Table,' ',@fillfactor)
-- SQL 2005 command
SET @cmd = 'ALTER INDEX ALL ON ' + @Table + ' REBUILD WITH (FILLFACTOR = ' + CONVERT(VARCHAR(3),@fillfactor) + ')'
EXEC (@cmd)
FETCH NEXT FROM TableCursor INTO @Table
END
CLOSE TableCursor
DEALLOCATE TableCursor
FETCH NEXT FROM DatabaseCursor INTO @Database
END
CLOSE DatabaseCursor
DEALLOCATE DatabaseCursor
Script to create commands to disable, enable, drop and recreate Foreign Key constraints in SQL Server
SET NOCOUNT ON
DECLARE @operation VARCHAR(10)
DECLARE @tableName sysname
DECLARE @schemaName sysname
SET @operation = 'DROP' --ENABLE, DISABLE, DROP
SET @tableName = 'SpecialOfferProduct'
SET @schemaName = 'Sales'
DECLARE @cmd NVARCHAR(1000)
DECLARE
@FK_NAME sysname,
@FK_OBJECTID INT,
@FK_DISABLED INT,
@FK_NOT_FOR_REPLICATION INT,
@DELETE_RULE smallint,
@UPDATE_RULE smallint,
@FKTABLE_NAME sysname,
@FKTABLE_OWNER sysname,
@PKTABLE_NAME sysname,
@PKTABLE_OWNER sysname,
@FKCOLUMN_NAME sysname,
@PKCOLUMN_NAME sysname,
@CONSTRAINT_COLID INT
DECLARE cursor_fkeys CURSOR FOR
SELECT Fk.name,
Fk.OBJECT_ID,
Fk.is_disabled,
Fk.is_not_for_replication,
Fk.delete_referential_action,
Fk.update_referential_action,
OBJECT_NAME(Fk.parent_object_id) AS Fk_table_name,
schema_name(Fk.schema_id) AS Fk_table_schema,
TbR.name AS Pk_table_name,
schema_name(TbR.schema_id) Pk_table_schema
FROM sys.foreign_keys Fk LEFT OUTER JOIN
sys.tables TbR ON TbR.OBJECT_ID = Fk.referenced_object_id --inner join
WHERE TbR.name = @tableName
AND schema_name(TbR.schema_id) = @schemaName
OPEN cursor_fkeys
FETCH NEXT FROM cursor_fkeys
INTO @FK_NAME,@FK_OBJECTID,
@FK_DISABLED,
@FK_NOT_FOR_REPLICATION,
@DELETE_RULE,
@UPDATE_RULE,
@FKTABLE_NAME,
@FKTABLE_OWNER,
@PKTABLE_NAME,
@PKTABLE_OWNER
WHILE @@FETCH_STATUS = 0
BEGIN
-- create statement for enabling FK
IF @operation = 'ENABLE'
BEGIN
SET @cmd = 'ALTER TABLE [' + @FKTABLE_OWNER + '].[' + @FKTABLE_NAME
+ '] CHECK CONSTRAINT [' + @FK_NAME + ']'
PRINT @cmd
END
-- create statement for disabling FK
IF @operation = 'DISABLE'
BEGIN
SET @cmd = 'ALTER TABLE [' + @FKTABLE_OWNER + '].[' + @FKTABLE_NAME
+ '] NOCHECK CONSTRAINT [' + @FK_NAME + ']'
PRINT @cmd
END
-- create statement for dropping FK and also for recreating FK
IF @operation = 'DROP'
BEGIN
-- drop statement
SET @cmd = 'ALTER TABLE [' + @FKTABLE_OWNER + '].[' + @FKTABLE_NAME
+ '] DROP CONSTRAINT [' + @FK_NAME + ']'
PRINT @cmd
-- create process
DECLARE @FKCOLUMNS VARCHAR(1000), @PKCOLUMNS VARCHAR(1000), @COUNTER INT
-- create cursor to get FK columns
DECLARE cursor_fkeyCols CURSOR FOR
SELECT COL_NAME(Fk.parent_object_id, Fk_Cl.parent_column_id) AS Fk_col_name,
COL_NAME(Fk.referenced_object_id, Fk_Cl.referenced_column_id) AS Pk_col_name
FROM sys.foreign_keys Fk LEFT OUTER JOIN
sys.tables TbR ON TbR.OBJECT_ID = Fk.referenced_object_id INNER JOIN
sys.foreign_key_columns Fk_Cl ON Fk_Cl.constraint_object_id = Fk.OBJECT_ID
WHERE TbR.name = @tableName
AND schema_name(TbR.schema_id) = @schemaName
ORDER BY Fk_Cl.constraint_column_id
OPEN cursor_fkeyCols
FETCH NEXT FROM cursor_fkeyCols INTO @FKCOLUMN_NAME,@PKCOLUMN_NAME
SET @COUNTER = 1
SET @FKCOLUMNS = ''
SET @PKCOLUMNS = ''
WHILE @@FETCH_STATUS = 0
BEGIN
IF @COUNTER > 1
BEGIN
SET @FKCOLUMNS = @FKCOLUMNS + ','
SET @PKCOLUMNS = @PKCOLUMNS + ','
END
SET @FKCOLUMNS = @FKCOLUMNS + '[' + @FKCOLUMN_NAME + ']'
SET @PKCOLUMNS = @PKCOLUMNS + '[' + @PKCOLUMN_NAME + ']'
SET @COUNTER = @COUNTER + 1
FETCH NEXT FROM cursor_fkeyCols INTO @FKCOLUMN_NAME,@PKCOLUMN_NAME
END
CLOSE cursor_fkeyCols
DEALLOCATE cursor_fkeyCols
-- generate create FK statement
SET @cmd = 'ALTER TABLE [' + @FKTABLE_OWNER + '].[' + @FKTABLE_NAME + '] WITH ' +
CASE @FK_DISABLED
WHEN 0 THEN ' CHECK '
WHEN 1 THEN ' NOCHECK '
END + ' ADD CONSTRAINT [' + @FK_NAME
+ '] FOREIGN KEY (' + @FKCOLUMNS
+ ') REFERENCES [' + @PKTABLE_OWNER + '].[' + @PKTABLE_NAME + '] ('
+ @PKCOLUMNS + ') ON UPDATE ' +
CASE @UPDATE_RULE
WHEN 0 THEN ' NO ACTION '
WHEN 1 THEN ' CASCADE '
WHEN 2 THEN ' SET_NULL '
END + ' ON DELETE ' +
CASE @DELETE_RULE
WHEN 0 THEN ' NO ACTION '
WHEN 1 THEN ' CASCADE '
WHEN 2 THEN ' SET_NULL '
END + '' +
CASE @FK_NOT_FOR_REPLICATION
WHEN 0 THEN ''
WHEN 1 THEN ' NOT FOR REPLICATION '
END
PRINT @cmd
END
FETCH NEXT FROM cursor_fkeys
INTO @FK_NAME,@FK_OBJECTID,
@FK_DISABLED,
@FK_NOT_FOR_REPLICATION,
@DELETE_RULE,
@UPDATE_RULE,
@FKTABLE_NAME,
@FKTABLE_OWNER,
@PKTABLE_NAME,
@PKTABLE_OWNER
END
CLOSE cursor_fkeys
DEALLOCATE cursor_fkeys
Running the script
- Table: SpecialOfferProduct
- Schema: Sales
- Operation: DROP
Example:
ALTER TABLE [Sales].[SalesOrderDetail] DROP CONSTRAINT [FK_SalesOrderDetail_SpecialOfferProduct_SpecialOfferIDProductID]
ALTER TABLE [Sales].[SalesOrderDetail] WITH NOCHECK ADD CONSTRAINT [FK_SalesOrderDetail_SpecialOfferProduct_SpecialOfferIDProductID] FOREIGN KEY ([SpecialOfferID],[ProductID]) REFERENCES [Sales].[SpecialOfferProduct] ([SpecialOfferID],[ProductID]) ON UPDATE NO ACTION ON DELETE NO ACTION
To check the powe of script and make it more useful, you can convert it into stored procedure
SQL Server 2000 - SET SHOWPLAN_ALL
Syntax: SET SHOWPLAN_ALL { ON OFF }
The setting of SET SHOWPLAN_ALL is set at execute or run time and not at parse time.
Run folowing Sql
USE pubs
GO
SET SHOWPLAN_ALL ON
GO
-- First query.
SELECT au_id
FROM authors
WHERE au_id = '409-56-7008'
GO
-- Second query.
SELECT city
FROM authors
WHERE city LIKE 'San%'
GO
SET SHOWPLAN_ALL OFF
GO
Understanding SQL Server Indexing
Problem:
With so many aspects of SQL Server to cover and to write about, some of the basic principals are often overlooked. There have been several people that have asked questions about indexing along with a general overview of the differences of clustered and non clustered indexes. Based on the number of questions that we have received, this tip will discuss the differences of indexes and some general guidelines around indexing.
Solution:
From a simple standpoint SQL Server offers two types of indexes clustered and non-clustered. In its simplest definition a clustered index is an index that stores the actual data and a non-clustered index is just a pointer to the data. A table can only have one Clustered index and up to 249 Non-Clustered Indexes. If a table does not have a clustered index it is referred to as a Heap. So what does this actually mean?
To further clarify this lets take a look at what indexes do and why they are important. The primary reason indexes are built is to provide faster data access to the specific data your query is trying to retrieve. This could be either a clustered or non-clustered index. Without having an index SQL Server would need to read through all of the data in order to find the rows that satisfy the query. If you have ever looked at a query plan the difference would be an Index Seek vs a Table Scan as well as some other operations depending on the data selected.
Here are some examples of queries that were run. These were run against table dbo.contact that has about 20,000 rows of data. Each of these queries was run with no index as well as with a clustered and non-clustered indexes. To show the impact a graphical query plan has been provided. This can be created by highlighting the query and pressing Control-L (Ctrl-L) in the query window.
1 - Table with no indexesWhen the query runs, since there are no indexes, SQL Server does a Table Scan against the table to look through every row to determine if any of the records have a lastname of "Adams". This query has an Estimated Subtree Cost of 0.437103. This is the cost to SQL Server to execute the query. The lower the number the less resource intensive for SQL Server.
2- Table with non-clustered index on lastname column
When this query runs, SQL Server uses the index to do an Index Seek and then it needs to do a RID Lookup to get the actual data. You can see from the Estimated Subtree Cost of 0.263888 that this is faster then the above query.
3- Table with clustered index on lastname column
When this query runs, SQL Server does an Index Seek and since the index points to the actual data pages, the Estimated Subtree Cost is only 0.0044572. This is by far the fastest access method for this type of query.
4- Table with non-clustered index on lastname column
In this query we are only requesting column lastname. Since this query can be handled by just the non-clustered index (covering query), SQL Server does not need to access the actual data pages. Based on this query the Estimated Subtree Cost is only 0.0033766. As you can see this even better then example #3.
To take this a step further, the below output is based on having a clustered index on lastname and no non-clustered index. You can see that the subtree cost is still the same as returning all of the columns even though we are only selecting one column. So the non-clustered index performs better.
5- Table with clustered index on contactId and non-clustered on lastname column
For this query we now have two indexes. A clustered and non-clustered. The query that is run in the same as example 2. From this output you can see that the RID Lookup has been replaced with a Clustered Index Seek. Overall it is the same type of operations, except using the Clustered Index. The subtree cost is 0.264017. This is a little better then example 2.
So based on these examples you can see the benefits of using indexes. This example table only had 20,000 rows of data, so this is quite small compared to most database tables. You can see the impact this would have on very large tables. The first idea that would come to mind is to use all clustered indexes, but because this is where the actual data is stored a table can only have one clustered index. The second thought may be to index every column. Although this maybe helpful when querying the data, there is also the overhead of maintaining all of these indexes every time you do an INSERT, UPDATE or DELETE.
Another thing you can see from these examples is ability to use non-clustered covering indexes where the index satisfies the entire result set. This is also faster then having to go to the data pages of the Heap or Clustered Index.
Saturday, April 12, 2008
Run The Same SQL Command Against All SQL Server Databases
[Where @sqlcommand is a variable-length string]
DECLARE @command varchar(1000)
SELECT @command = 'IF ''?'' NOT IN(''master'', ''model'', ''msdb'', ''tempdb'') BEGIN USE ? EXEC(''CREATE PROCEDURE pNewProcedure1 AS SELECT name, createdate, updatedate FROM sys.sysusers ORDER BY updatedate DESC'') END'
EXEC sp_MSforeachdb @command
Friday, April 11, 2008
Span vs. Div Tags
1.Div stands for Division which means to divide a place or body or page where need to show some tasks. So, Div tag is nothing but its Divide a page or in another words its a block element which blocks the entire page withing
tags
2.On the other hand, span is an inline element.So, its print in the same line.
Check following example:
<html>
<head>
<title>Div vs Span</title></head>
<body>
<P><b>Difference : Div and Span</b></p>
<b>Span Example</b><br/>
<span>This line is within the span tag and will output in same line.</span>
<p>
<b>Div Example</b></p>
<div>This line is within the div tag.
<p>We can use paragraphs within division but not divisions within paragraphs.</p>
</div>
</body>
</html>