c# generate barcode free Using a Multicolumn CHECK Constraint in Font

Generating USS Code 39 in Font Using a Multicolumn CHECK Constraint

Using a Multicolumn CHECK Constraint
Code 3/9 Generator In None
Using Barcode maker for Font Control to generate, create Code 39 Full ASCII image in Font applications.
www.OnBarcode.com
GS1 - 12 Creator In None
Using Barcode drawer for Font Control to generate, create UPCA image in Font applications.
www.OnBarcode.com
A CHECK constraint can also have multiple columns. In the context of the ClassGrades table, you can specify a set of valid letter grades and a range of valid integer values to denote classes. Rows with GradeLetter values outside the letter range or ClassID values outside of scope of valid numbers for classes can be rejected by a CHECK constraint. The following CREATE TABLE statement is from the Ch04CheckPKStudentGrades.sql file. The file s contents are exactly the same as for the CREATE TABLE statement in the preceding sample, except for one constraint.
Encoding Code 39 Full ASCII In None
Using Barcode drawer for Font Control to generate, create ANSI/AIM Code 39 image in Font applications.
www.OnBarcode.com
Barcode Creation In None
Using Barcode creation for Font Control to generate, create Barcode image in Font applications.
www.OnBarcode.com
CHAPTER 4 DATA TYPES, TABLES, AND CONSTRAINTS
Make Data Matrix In None
Using Barcode generator for Font Control to generate, create Data Matrix image in Font applications.
www.OnBarcode.com
Make PDF417 In None
Using Barcode creator for Font Control to generate, create PDF-417 2d barcode image in Font applications.
www.OnBarcode.com
The new constraint is the CK_GradeLetter_ClassID CHECK constraint at the end of the statement. Notice the new constraint is comma delimited from the preceding PRIMARY KEY constraint. The CHECK constraint has two expressions for restricting the content in two columns. The first expression designates the range of legitimate letters for grades in the GradeLetter column, namely, A F. The second expression indicates that the most positive ClassID value is less than 1,000, namely, 999. An AND operator joins the two expressions so that the data for a new row must comply with both expressions to be valid data according to the CK_GradeLetter_ClassID CHECK constraint. CREATE TABLE ClassGrades( ClassID int, StudentID int, GradeLetter varchar(2), Constraint PK_ClassGrades PRIMARY KEY(ClassID, StudentID), Constraint CK_GradeRange_ClassID CHECK (LEFT(UPPER(GradeLetter),1) LIKE '[A-F]' AND ClassID < 1000) ) The following set of five INSERT statements attempt to add five new rows, but only three attempts succeed. The third and fourth INSERT statements fail. The third statement fails because its GradeLetter value (V ) has a letter outside of the bounds for legitimate letter grades (A F). The fourth statement fails because its ClassID value (1001) is greater than the upper limit for ClassID values (999). INSERT INSERT INSERT INSERT INSERT ClassGrades ClassGrades ClassGrades ClassGrades ClassGrades VALUES(1, 1, 'C+') VALUES(1, 2, 'A+') VALUES(1, 3, 'V-') VALUES(1001, 1, 'A') VALUES(999, 2, 'A')
Code 128C Generator In None
Using Barcode maker for Font Control to generate, create Code-128 image in Font applications.
www.OnBarcode.com
Making RM4SCC In None
Using Barcode encoder for Font Control to generate, create British Royal Mail 4-State Customer Barcode image in Font applications.
www.OnBarcode.com
Using Foreign Key Constraints
Drawing Code-39 In None
Using Barcode creation for Font Control to generate, create USS Code 39 image in Font applications.
www.OnBarcode.com
Code39 Creation In Java
Using Barcode encoder for Eclipse BIRT Control to generate, create Code 39 Full ASCII image in BIRT applications.
www.OnBarcode.com
A foreign key constraint is one or more columns in a secondary table that points at corresponding columns in a primary table. For example, if Classes was a primary table, then a secondary table could be ClassGrades. The secondary table, ClassGrades, can use its ClassID column to point back at the ClassID column in the Classes table. Any secondary table can point at multiple primary tables, and therefore have multiple foreign keys. For example, the ClassGrades secondary table can also point at a Students primary table. SQL Server Express enforces referential integrity by maintaining consistent values in the FOREIGN KEY columns of a secondary table and the PRIMARY KEY columns or the UNIQUE constraint columns of the primary table. Referential integrity rules restrict
GS1 DataBar Generation In .NET Framework
Using Barcode generator for VS .NET Control to generate, create DataBar image in Visual Studio .NET applications.
www.OnBarcode.com
Encode Barcode In Objective-C
Using Barcode drawer for iPad Control to generate, create Barcode image in iPad applications.
www.OnBarcode.com
CHAPTER 4 DATA TYPES, TABLES, AND CONSTRAINTS
Code 3 Of 9 Creation In .NET Framework
Using Barcode printer for .NET framework Control to generate, create Code-39 image in Visual Studio .NET applications.
www.OnBarcode.com
Barcode Maker In None
Using Barcode printer for Excel Control to generate, create Barcode image in Microsoft Excel applications.
www.OnBarcode.com
Column values in FOREIGN KEY columns to those that match values in the corresponding columns of the primary table The revision or deletion of column values in a primary table that will orphan rows in a secondary table You can use a FOREIGN KEY constraint to designate a relationship between columns in a secondary table that points at columns that are a PRIMARY KEY or UNIQUE constraint in a primary table. SQL Server Express permits the declaration of FOREIGN KEY constraints at the column and table level. A table-level declaration of a FOREIGN KEY constraint is essential when a single foreign key extends across multiple columns. However, table-level declarations for single-column foreign keys can also improve the readability of the declarations for the associated columns. Foreign keys optionally allow the specification of rules to define how foreign key columns in a secondary table will change when corresponding column values in the primary table are updated or deleted. To designate how the secondary table can change in response to updates and deletes in the primary table, you need to include the ON UPDATE or ON DELETE phrases in the FOREIGN KEY constraint declaration. Follow the ON UPDATE or ON DELETE keyword with a keyword to specify the action you wish to happen. The default rule prohibits changes to a primary table that require a corresponding change in a secondary table. In other words, the default rule allows no action to the primary table that requires a corresponding change to the secondary table. You can optionally specify the NO ACTION phrase to designate the default rule. In fact, ON UPDATE and ON DELETE are not necessary when the default action is acceptable. CASCADE extends the action for a row in the primary table to the corresponding rows in the secondary table. CASCADE after ON DELETE causes the deletion of rows in a secondary table that correspond to a deleted row in a primary table. CASCADE after ON UPDATE causes the revision of foreign key values after matching column values are updated in a primary table. SET NULL causes foreign key column values to be set to null values when updates or deletes occur to matching values in a primary table. SET DEFAULT causes foreign key column values to equal their DEFAULT property setting when updates or deletes occur to matching values in a primary table.
Drawing PDF 417 In Java
Using Barcode maker for Android Control to generate, create PDF-417 2d barcode image in Android applications.
www.OnBarcode.com
UPC A Reader In Visual C#
Using Barcode decoder for Visual Studio .NET Control to read, scan read, scan image in VS .NET applications.
www.OnBarcode.com
UCC-128 Recognizer In Visual C#
Using Barcode recognizer for VS .NET Control to read, scan read, scan image in .NET framework applications.
www.OnBarcode.com
Encode Code 128 Code Set C In Objective-C
Using Barcode creation for iPad Control to generate, create Code 128 Code Set B image in iPad applications.
www.OnBarcode.com
Generating Linear 1D Barcode In Visual C#
Using Barcode generation for .NET framework Control to generate, create Linear 1D Barcode image in Visual Studio .NET applications.
www.OnBarcode.com
Barcode Drawer In Java
Using Barcode drawer for BIRT Control to generate, create Barcode image in Eclipse BIRT applications.
www.OnBarcode.com
Copyright © OnBarcode.com . All rights reserved.