The SIMILAR TO Regular Expression Symbols in .NET framework

Generation GTIN - 13 in .NET framework The SIMILAR TO Regular Expression Symbols

Table 8-4 The SIMILAR TO Regular Expression Symbols
Scanning GTIN - 13 In .NET Framework
Using Barcode Control SDK for VS .NET Control to generate, create, read, scan barcode image in Visual Studio .NET applications.
European Article Number 13 Generation In .NET Framework
Using Barcode maker for .NET framework Control to generate, create EAN-13 Supplement 5 image in .NET framework applications.
PostgreSQL 8 for Windows
Recognize EAN13 In Visual Studio .NET
Using Barcode recognizer for .NET framework Control to read, scan read, scan image in VS .NET applications.
Printing Bar Code In Visual Studio .NET
Using Barcode maker for Visual Studio .NET Control to generate, create barcode image in .NET framework applications.
Testing if a column data value is NULL can be tricky You cannot use standard mathematical operators to check if a value is NULL, as you cannot compare two unknown values Another thing to remember is that the NULL value is not the same thing as either an empty string or the numeric value of zero This confuses and traps many a novice database programmer To add insult to injury, there is some controversy between the various database engine vendors as to exactly how to handle NULL values (see 12) This can often make porting a database application from one vendor s database engine to another s extremely complicated The ANSI SQL standard provides the IS NULL and IS NOT NULL operators to help you determine when a column value is NULL PostgreSQL fully supports the IS NULL operator The IS NULL operator is the only way to determine if a column value is empty Here is an example of using the IS NULL operator to check a column value First, you must create a record that contains a NULL value for a column value This can be done by inserting a new record and not assigning a value to one or more data columns (remember, some of the columns were created so that they cannot be NULL):
Bar Code Decoder In Visual Studio .NET
Using Barcode reader for .NET Control to read, scan read, scan image in Visual Studio .NET applications.
European Article Number 13 Printer In C#.NET
Using Barcode creation for .NET framework Control to generate, create GTIN - 13 image in .NET applications.
test=> insert into store"Customer" ("CustomerID", "LastName", "Phone") test-> values ('MUL001', 'Mullen', '555-4829'); INSERT 0 1 test=>
Draw UPC - 13 In Visual Studio .NET
Using Barcode drawer for ASP.NET Control to generate, create EAN-13 image in ASP.NET applications.
Paint EAN 13 In Visual Basic .NET
Using Barcode drawer for VS .NET Control to generate, create EAN / UCC - 13 image in .NET framework applications.
Now you can perform a query on the table, looking for records that contain a NULL value for one of the missing data columns:
Creating GS1-128 In VS .NET
Using Barcode drawer for Visual Studio .NET Control to generate, create GS1 128 image in Visual Studio .NET applications.
Creating GS1 DataBar Expanded In .NET
Using Barcode drawer for .NET Control to generate, create GS1 DataBar Limited image in Visual Studio .NET applications.
test=> select * from store"Customer" where "FirstName" IS NULL; CustomerID | LastName | FirstName | Address | City | State | Zip | Phone + + + + + + + MUL001 | Mullen | | | | | | 555-4829 (1 row) test=>
Creating ECC200 In .NET Framework
Using Barcode maker for VS .NET Control to generate, create ECC200 image in .NET applications.
Generate USD-4 In .NET
Using Barcode printer for VS .NET Control to generate, create 2 of 7 Code image in VS .NET applications.
The preceding SQL command queries the table, looking for records that do not have a value in the FirstName column Sure enough, the new record appears in the result set To see how easy it is to confuse NULL values with empty strings, we can create a record containing an empty string value, then try to use the IS NULL operator to find it:
UCC - 12 Generation In VB.NET
Using Barcode generator for .NET Control to generate, create GS1 - 12 image in .NET applications.
Making GS1 128 In .NET
Using Barcode creation for ASP.NET Control to generate, create UCC.EAN - 128 image in ASP.NET applications.
test=> update store"Customer" set "FirstName" = '' test-> where "CustomerID" = 'MUL001'; UPDATE 1 test=> select * from store"Customer" where "FirstName" IS NULL; CustomerID | LastName | FirstName | Address | City | State | Zip | Phone + + + + + + + (0 rows) test=>
Bar Code Recognizer In Visual C#
Using Barcode reader for Visual Studio .NET Control to read, scan read, scan image in .NET applications.
Draw UPC-A In Java
Using Barcode printer for Java Control to generate, create UPC-A Supplement 2 image in Java applications.
8:
GTIN - 13 Reader In Java
Using Barcode recognizer for Java Control to read, scan read, scan image in Java applications.
Create USS Code 39 In Java
Using Barcode printer for BIRT Control to generate, create ANSI/AIM Code 39 image in Eclipse BIRT applications.
PostgreSQL Functions
Drawing 2D Barcode In Java
Using Barcode creator for Java Control to generate, create 2D Barcode image in Java applications.
Code-39 Maker In Java
Using Barcode drawer for Android Control to generate, create Code 39 Extended image in Android applications.
Since the FirstName column has a value now, even though it is an empty string, the IS NULL operator does not filter the record out You can also set a column value to NULL by using the NULL keyword:
test=> update store"Customer" set "FirstName" = NULL test-> where "CustomerID" = 'MUL001'; UPDATE 1 test=> select * from store"Customer" where "FirstName" IS NULL; CustomerID | LastName |FirstName| Address | City | State | Zip | Phone + + + + + + + MUL001 | Mullen | | | | | | 555-4829 (1 row) test=>
Setting the FirstName column value to NULL has the same effect as creating the new record with a column value
Built-in Functions
Besides all of the standard operators, the PostgreSQL developers also included many useful functions for use with various data types As with operators, functions can be used in any expression value within the SQL command To get an idea of the number of functions available in PostgreSQL, try the following \df meta-command from psql The output goes on for quite a long time Just as with the operators listing, you can specify a specific function to view information on only that function Also just as with operators, notice that within the functions available, there are often several versions of the same function, depending on the input data types
test=> \df area List of functions Schema | Name | Result data type | Argument data types + + + pg_catalog | area | double precision | box pg_catalog | area | double precision | circle pg_catalog | area | double precision | path (3 rows) test=>
The area() function has three different versions, depending on the data type of the input data Even though the three formats use different input data types, they all use the same data type for the result Just as with operators, it is imperative that you use the correct input data types with the correct functions There is not much sense in trying to calculate the square root of
Copyright © OnBarcode.com . All rights reserved.