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This article shows you what ADO.NET functions have, which are concise and easy to understand, which can definitely brighten your eyes. I hope you can get something through the detailed introduction of this article.

The use of functions to make our programming more convenient, a function can achieve a function, let us greatly reduce the amount of code, here we briefly introduce the ADO.NET function.

If you want the column to contain expressions with more complex logic, you can embed some ADO.NET functions in the column. Expressions can contain functions such as Len, Iif, IsNull, Convert, Trim, and Substring. These ADO.NET functions provide more flexibility in building expressions. The Len function calculates the length of the string:

ODs.Tables ["OrderDetail"] .Columns.add ("LengthOfProductName", typeof (int), "Len (ProductName)")

The Iif function is an iterative If statement, like IIf in Visual Basic .NET. It has three parameters and calculates the true and false of * parameters. If the calculated value of the * parameter is true, the second argument is returned from the Iif function, otherwise the third argument is returned. The following is basically a condensed If...Then...Else statement that can be simply written as an embedded expression:

ODs.Tables ["OrderDetail"] .Columns.Add ("Inventory", typeof (string), "Iif (Quantity < 10 few left', 'Plenty in stock')")

The IsNull function evaluates * * parameters to see if they are equal to System.DbNull. If the result of the calculation is false, the function returns * * parameter values, and if true, the second parameter value. This is used when null values are not allowed and you want to replace them with empty strings or placeholders:

ODs.Tables ["OrderDetail"] .Columns.add ("DiscountString", typeof (string), "IsNull (Discount,'[null value]')")

The Trim function removes the space at the end of the string value. The Convert function converts the data type in the expression to the data type referred to in the second argument of the ADO.NET function. The Substring function returns a portion of a string, which can be used to shorten a long string and display only fixed-length strings. It can return any part of the string and use oDs.Tables ["OrderDetail"] .Columns.Add ("ShortProduct", typeof (string), "Substring (ProductName, 1,10)"); as needed.

What are the ADO.NET functions mentioned above? have you learned any knowledge or skills? If you want to learn more skills or enrich your knowledge reserve, you are welcome to follow the industry information channel.

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