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This article introduces the relevant knowledge of "how to realize the automatic increment column of ADO.NET". Many people will encounter such a dilemma in the operation of actual cases, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

1.ADO.NET expression column

ADO.NET also allows users to create and define expression columns. Expressions in ADO+ are used to filter, calculate, and summarize column information

To create an expression column, you need to set the DataType property to the type appropriate for the value returned by the expression, and then set the Expression property to a valid expression:

DataColumn dc = New DataColumn; dc.DataType = System.Type.GetType ("System.Currency"); dc.Expression = "total * .086"

You can also use the Add method to create an expression column. For example, the following code adds a column that calculates a discount based on 10% of the customer's purchase amount. This expression multiplies the column named "Purchases" by 10%.

When the table adds data, the value of this column will be 10% of the value in the total column

DataColumn dc= New DataColumn; dc= dt.Columns.Add ("rectg", System.Type.GetType ("System.Double"), "total * 0.1")

2.ADO.NET auto increment column

Another feature of DataColumn is its ability to act as an automatic increment column. Auto increment column automatically increases the value in a new column when it is added. To create an auto-increment column, you need to set the AutoIncrement property of the column to true. Once this property is set, the column starts with the numeric value defined in the column's AutoIncrementSeed property. After a column is added, the value of the auto-increment column is incremented as a step by the value in the column's AutoIncrementStep property.

Dc = dt.Columns.Add ("CustID", System.Type.GetType ("System.Int32")); dc.AutoIncrement = true; dc.AutoIncrementSeed = 1; dc.AutoIncrementStep = 1

Create a primary keyword for the table

Dt.PrimaryKey = new DataColumn [] {dt ["CustID"]}

3.ADO.NET adds data to the table

Now that you have a table with columns and keywords, you can add some data.

DataRow dtRow = null; for (int I = 0; I

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