rdlc qr code

rdlc qr code

rdlc qr code

If you modify the data source so that it returns a different set of columns, you can regenerate the GridView columns. Just select the GridView, and click the Refresh Schema link in the smart tag. This step will wipe out any custom columns you ve added (such as editing controls).

The GridView examples you ve seen so far have set the GridView.AutoGenerateColumns property to True. When this property is set, the GridView uses reflection to examine that data object and finds all the fields (of a record) or properties (of a custom object). It then creates a column for each one, in the order that it finds it. This automatic column generation is good for creating quick test pages, but it doesn t give you the flexibility you ll usually want. For example, what if you want to hide columns, change their order, or configure some aspect of their display, such as the formatting or heading text In all of these cases, you ll need to set AutoGenerateColumns to False and define the columns yourself in the <Columns> section of the GridView control tag.

Once you ve specified the provider name and connection string, the next step is to add the query logic that the SqlDataSource will use when it connects to the database.

Here s a complete GridView declaration with explicit columns: <asp:GridView ID="gridEmployees" runat="server" DataSourceID="sourceEmployees" AutoGenerateColumns="False"> <Columns> <asp:BoundField DataField="EmployeeID" HeaderText="ID" /> <asp:BoundField DataField="FirstName" HeaderText="First Name" /> <asp:BoundField DataField="LastName" HeaderText="Last Name" />

You can use each SqlDataSource control you create to retrieve a single query. Optionally, you can also add corresponding commands for deleting, inserting, and updating rows. For example, one SqlDataSource is enough to query and update the Customers table in the Northwind database. However, if you need to independently retrieve or update Customers and Orders information, you ll need two SqlDataSource controls. The SqlDataSource command logic is supplied through four properties: SelectCommand, InsertCommand, UpdateCommand, and DeleteCommand, each of which takes a string. The string you supply can be inline SQL (in which case the corresponding SelectCommandType, InsertCommandType, UpdateCommandType, or DeleteCommandType property should be Text, the default) or the name of a stored procedure (in which case the command type is StoredProcedure). You need to define commands only for the types of actions you want to perform. In other words, if you re using a data source for read-only access to a set of records, you need to define only the SelectCommand property.

It s possible to have AutoGenerateColumns set to True and define columns in the <Columns> section. In this case, the columns you explicitly defined are added before the autogenerated columns. This technique was used in the previous chapter to create a GridView with automatically generated bound columns and a manually defined column with edit controls. However, for the most flexibility you ll usually want to explicitly define every column.

<asp:BoundField DataField="Title" HeaderText="Title" /> <asp:BoundField DataField="City" HeaderText="City" /> </Columns> </asp:GridView> When you explicitly declare a bound field, you have the opportunity to set other properties. Table 10-2 lists these properties. Table 10-2. BoundField Properties

If you configure a command in the Properties window, you ll see a property named SelectQuery instead of SelectCommand. The SelectQuery is actually a virtual property that s displayed as a design-time convenience. When you edit the SelectQuery (by clicking the ellipsis next to the property name), you can use a special designer to write the command text (the SelectCommand) and add command parameters (the SelectParameters).

Each column can be any of several different types, as described in Table 10-1. The order of your column tags determines the right-to-left order of columns in the GridView. Table 10-1. Column Types

The name of the field (for a row) or property (for an object) of the data item that you want to display in this column A format string that formats the field This is useful for getting the right representation of numbers and dates If true, the format string will be used to format the value even when it appears in a text box in edit mode The default is false, which means only the underlying normal will be used (114302 instead of $1,14302) Sets the text in the header and footer region of the grid, if this grid has a heater (ShowHeader is true) and Footer (ShowFooter is true).