create barcode labels c# Note You can t use ALTER TABLE to modify a constraint de nition. You must use ALTER TABLE to in VB.NET

Creating Universal Product Code version A in VB.NET Note You can t use ALTER TABLE to modify a constraint de nition. You must use ALTER TABLE to

Note You can t use ALTER TABLE to modify a constraint de nition. You must use ALTER TABLE to
UPCA Generation In Visual Basic .NET
Using Barcode creation for Visual Studio .NET Control to generate, create UPC A image in .NET framework applications.
www.OnBarcode.com
Read GS1 - 12 In Visual Basic .NET
Using Barcode scanner for Visual Studio .NET Control to read, scan read, scan image in Visual Studio .NET applications.
www.OnBarcode.com
drop the constraint and then use ALTER TABLE to add a new constraint with the new de nition.
Print Bar Code In VB.NET
Using Barcode creator for .NET Control to generate, create bar code image in VS .NET applications.
www.OnBarcode.com
Barcode Scanner In VB.NET
Using Barcode decoder for .NET framework Control to read, scan read, scan image in VS .NET applications.
www.OnBarcode.com
Dropping a Column
UPC Code Maker In C#
Using Barcode creator for Visual Studio .NET Control to generate, create GTIN - 12 image in VS .NET applications.
www.OnBarcode.com
Printing UPCA In .NET
Using Barcode generator for ASP.NET Control to generate, create UPC-A Supplement 5 image in ASP.NET applications.
www.OnBarcode.com
You can use ALTER TABLE to remove one or more columns from a table. However, you can t drop the following columns:
Drawing GTIN - 12 In .NET
Using Barcode encoder for Visual Studio .NET Control to generate, create UPC-A Supplement 2 image in .NET applications.
www.OnBarcode.com
Encode Code 128C In VB.NET
Using Barcode creator for Visual Studio .NET Control to generate, create Code 128A image in .NET framework applications.
www.OnBarcode.com
A replicated column A column used in an index A column used in a CHECK, FOREIGN KEY, UNIQUE, or PRIMARY KEY constraint A column associated with a default de ned using the DEFAULT keyword or bound to a default object A column to which a rule is bound
Encode Matrix 2D Barcode In VB.NET
Using Barcode generation for VS .NET Control to generate, create 2D Barcode image in VS .NET applications.
www.OnBarcode.com
Drawing Bar Code In VB.NET
Using Barcode generation for .NET Control to generate, create bar code image in Visual Studio .NET applications.
www.OnBarcode.com
You can drop a column using the following syntax:
UPC A Maker In Visual Basic .NET
Using Barcode generator for Visual Studio .NET Control to generate, create UPCA image in .NET applications.
www.OnBarcode.com
Drawing UPC - E0 In Visual Basic .NET
Using Barcode drawer for .NET Control to generate, create UPC-E Supplement 2 image in .NET applications.
www.OnBarcode.com
ALTER TABLE table-name DROP COLUMN column-name [, next-column-name]...
UPCA Maker In None
Using Barcode printer for Font Control to generate, create Universal Product Code version A image in Font applications.
www.OnBarcode.com
EAN13 Maker In Java
Using Barcode printer for Eclipse BIRT Control to generate, create EAN13 image in BIRT reports applications.
www.OnBarcode.com
Note Notice the syntax difference between dropping a column and adding a new column: the word COLUMN is required when dropping a column but not when you add a new column to a table.
Print Bar Code In Objective-C
Using Barcode maker for iPhone Control to generate, create barcode image in iPhone applications.
www.OnBarcode.com
Paint Code 3 Of 9 In None
Using Barcode creator for Software Control to generate, create Code39 image in Software applications.
www.OnBarcode.com
Microsoft SQL Server 2008 Internals
Draw EAN 128 In None
Using Barcode creation for Excel Control to generate, create USS-128 image in Microsoft Excel applications.
www.OnBarcode.com
Recognize UPC A In C#.NET
Using Barcode decoder for VS .NET Control to read, scan read, scan image in Visual Studio .NET applications.
www.OnBarcode.com
Enabling or Disabling a Trigger
Generate QR-Code In None
Using Barcode creator for Font Control to generate, create QR Code 2d barcode image in Font applications.
www.OnBarcode.com
Code39 Drawer In Objective-C
Using Barcode creation for iPhone Control to generate, create Code 3 of 9 image in iPhone applications.
www.OnBarcode.com
You can enable or disable one or more (or all) triggers on a table using the ALTER TABLE command.
Internals of Altering Tables
Note that not all the ALTER TABLE variations require SQL Server to change every row when the ALTER TABLE is issued. SQL Server can carry out an ALTER TABLE command in three basic ways:
It might need to change only metadata. It might need to examine all the existing data to make sure it is compatible with the change but only needs to make changes to metadata. It might need to change every row physically.
In many cases, SQL Server can just change the metadata (primarily the data seen through sys.columns) to re ect the new structure. In particular, the data isn t touched when a column is dropped, when a new column is added and NULL is assumed as the new value for all rows, when the length of a variable-length column is increased, or when a non-nullable column is changed to allow NULLs. The fact that data isn t touched when a column is dropped means that the disk space of the column is not reclaimed. You might have to reclaim the disk space of a dropped column when the row size of a table approaches or has exceeded its limit. You can reclaim space by creating a clustered index on the table or rebuilding an existing clustered index by using ALTER INDEX, as we ll see in 6. Some changes to a table s structure require that the data be examined but not modi ed. For example, when you change the nullability property to disallow NULLs, SQL Server must rst make sure there are no NULLs in the existing rows. A variable-length column can be shortened when all the existing data is within the new limit, so the existing data must be checked. If any rows have data longer than the new limit speci ed in the ALTER TABLE, the command fails. So you do need to be aware that for a huge table, this can take some time. Changing a xed-length column to a shorter type, such as changing an int column to smallint or changing a char(10) to char(8), also requires examining all the data to verify that all the existing values can be stored in the new type. However, even though the new data type takes up fewer bytes, the rows on the physical pages are not modi ed. If you have created a table with an int column, which needs 4 bytes in each row, all rows will use the full 4 bytes. After altering the table to change the int to smallint, we are restricted in the range of data values we can insert, but the rows continue to use 4 bytes for each value, instead of the 2 bytes that smallint requires. You can verify this by using the DBCC PAGE command. Changing a char(10) to char(8) displays similar behavior, and the rows continue to use 10 bytes for that column, but only 8 are allowed to have new data inserted. It is not until the table is rebuilt by creating or re-creating a clustered index that the char(10) columns are actually re-created to become char(8).
Copyright © OnBarcode.com . All rights reserved.