barcode generator project source code in vb.net Maintaining Data Using DML in Software

Generating PDF 417 in Software Maintaining Data Using DML

Maintaining Data Using DML
PDF417 Decoder In None
Using Barcode Control SDK for Software Control to generate, create, read, scan barcode image in Software applications.
PDF 417 Generator In None
Using Barcode creation for Software Control to generate, create PDF417 image in Software applications.
Another important consideration is the constraints de ned on the table referenced by the DML statement. The DBMS will not perform any modi cation to the data in the database if it violates one of the constraints. When forming DML statements, you need to consider the following in regard to the constraints on the table being modi ed: Primary key constraints When you insert a new row into a table, the primary key of the new row must be unique among all rows in the table. When you modify a primary key value (which is rarely done), the new value must be unique among all rows in the table. Unique constraints As with primary key columns, columns with a unique constraint de ned on them must always have values that are unique among all rows in the table. Referential constraints You cannot insert or update a foreign key value unless the corresponding parent row containing the key value in its primary key column(s) already exists. Conversely, you cannot delete a parent row if there are any child rows that still reference it unless the constraint includes an ON DELETE CASCADE option. In general, table inserts have to be in hierarchical sequence (parents before children) and deletes done in the reverse sequence (children before parents). NOT NULL constraints For an INSERT, you must provide values for any columns that have NOT NULL constraints. For an UPDATE, you cannot change columns to null values if they have a NOT NULL constraint. If the DML statement references a view, you cannot use it for INSERTS if any of the table s required columns (those with NOT NULL constraints) are missing from the view de nition. CHECK constraints An INSERT or UPDATE statement cannot apply a value to a table column that violates any CHECK constraint on that column.
PDF417 Reader In None
Using Barcode decoder for Software Control to read, scan read, scan image in Software applications.
PDF417 Encoder In Visual C#.NET
Using Barcode drawer for VS .NET Control to generate, create PDF-417 2d barcode image in VS .NET applications.
The INSERT Statement
Drawing PDF417 In .NET Framework
Using Barcode maker for ASP.NET Control to generate, create PDF-417 2d barcode image in ASP.NET applications.
Painting PDF-417 2d Barcode In VS .NET
Using Barcode creator for .NET framework Control to generate, create PDF 417 image in .NET framework applications.
The INSERT statement in SQL is used to add new rows of data to tables. It comes in two basic forms: one where column values are provided in the statement itself, and the other where values are selected from a table or view using a subselect. Let s have a look at those two forms.
PDF417 Printer In Visual Basic .NET
Using Barcode drawer for Visual Studio .NET Control to generate, create PDF-417 2d barcode image in .NET framework applications.
Code-128 Creation In None
Using Barcode encoder for Software Control to generate, create Code 128 image in Software applications.
SQL Demysti ed
Generating Bar Code In None
Using Barcode encoder for Software Control to generate, create barcode image in Software applications.
Encode EAN-13 Supplement 5 In None
Using Barcode generator for Software Control to generate, create EAN13 image in Software applications.
Single Row Inserts Using the VALUES Clause
Generate EAN / UCC - 13 In None
Using Barcode generation for Software Control to generate, create EAN128 image in Software applications.
Encoding Data Matrix ECC200 In None
Using Barcode creation for Software Control to generate, create Data Matrix 2d barcode image in Software applications.
The INSERT statement that uses a VALUES clause can create only one row each time it is run because the values for that one row of data are provided in the statement itself. Here is the general syntax for the statement:
Draw Industrial 2 Of 5 In None
Using Barcode drawer for Software Control to generate, create 2/5 Standard image in Software applications.
Linear Drawer In Visual Basic .NET
Using Barcode generator for VS .NET Control to generate, create 1D image in .NET applications.
INSERT INTO table_or_view_name [(column_list)] VALUES (value_list);
Code-128 Encoder In Objective-C
Using Barcode maker for iPhone Control to generate, create Code 128 image in iPhone applications.
Printing EAN-13 In Java
Using Barcode encoder for Eclipse BIRT Control to generate, create EAN-13 Supplement 5 image in Eclipse BIRT applications.
Note the following: The column list is optional but if included must be enclosed in a pair of parentheses. If the column list is omitted, a value must be provided for every column in the table in the same order as the columns are de ned in the table. It is always a good idea to provide the column list, because leaving it out makes the INSERT statement dependent on the table s de nition, which means that if the column order is changed, or a new column is added to the table (even an optional one), the INSERT statement will most likely fail the next time it is run. If the column list is provided, the value list must provide a value for each column in the column list and in the same order. In other words, the column list and value list must have a one-to-one correspondence. Any column that is omitted from the column list will be set to a null value, provided nulls are allowed for that column. The keyword NULL may be used in the value list to specify a null value for any column. In Microsoft SQL Server and Sybase Adaptive Server, you cannot insert values into a column with the IDENTITY property set. The IDENTITY property is a commonly used method for assigning sequential values to a primary key, such as the MOVIE_ID column in the MOVIE table. If the IDENTITY property is set, you can simply not reference the column in the SQL INSERT statement and the DBMS will assign the next unique value to the primary key. Alternatively, you can turn off the restriction by running this statement:
Encoding Bar Code In None
Using Barcode generation for Font Control to generate, create bar code image in Font applications.
Making Bar Code In Visual Studio .NET
Using Barcode creator for Reporting Service Control to generate, create barcode image in Reporting Service applications.
EAN128 Creation In Objective-C
Using Barcode creator for iPhone Control to generate, create GS1-128 image in iPhone applications.
Drawing Code 128B In C#
Using Barcode creator for .NET Control to generate, create Code 128 image in VS .NET applications.
Copyright © OnBarcode.com . All rights reserved.