C# oracle update

In the Properties window, change the Text of the label to Department. In the Properties window, under Design, change the Name to departments. Typed accessors, such as GetString , return native. NET data types and native Oracle data types. Zero-based ordinals passed to the accessors specify which column in the result set to return. Bind variables are placeholders inside a SQL statement.

When a database receives a SQL statement, it determines if the statement has already been executed and stored in memory. If the statement does exist in memory, Oracle Database can reuse it and skip the task of parsing and optimizing the statement. Using bind variables makes the statement reusable with different input values. Using bind variables also improves query performance in the database, eliminates the need for special handling of literal quotation marks in the input, and protects against SQL injection attacks.

A bind variable identifier always begins with a single colon :. You can use the OracleParameter class to represent each bind variable in your.

NET code. The OracleCommand class passes your SQL statement to the database and returns the results to your application. You can bind variables by position or by name by setting the OracleCommand property BindByName which defaults to false.

You must use the Add method to add the parameters to the OracleParameterCollection in the same order as they appear in the SQL statement or stored procedure. You may add the parameters to the collection in any order; however, you must set the ParameterName property for the parameter object to the same name as the bind variable identifier in the stored procedure declaration.

In addition to the binding mode by position or by name , the. The Direction property indicates the direction of each parameter. The default value of the Direction property is Input. For this code, the parameter object sets the OracleDbType property, but there is no need to set the Direction property because it uses the default value, Input. There is no need to set the Size property because the object is an input parameter, and the data provider can determine the size from the value.

Enter the login information, and a typical department number, such as 50, from the HR schema. You frequently need to retrieve more than just one value from the database. A DataReader object can retrieve values for multiple columns and multiple rows. Consider the multiple column, multiple row query in the following example:. Processing multiple rows from the DataReader object requires a looping construct. Also, a control that can display multiple rows is useful.

Because the OracleDataReader object is a forward-only, read-only cursor, it cannot be bound to an updatable or backward scrollable control such as Windows Forms DataGrid control. The DataSet class provides a memory-resident copy of database data.

It consists of one or more tables that store relational or XML data. If you have not done so before, make another copy of the Form1 that you completed in Chapter 3, and name it Form3.

If Form1. In the Properties window, change the Name of the data grid view to departments. Immediately after the conn declaration in the code, add variable declarations to the class variables, as indicated.

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Required Invalid security code. I declare, I accept the site's Privacy Policy. Add Comment. What our readers say. Error Details. This site makes use of Cookies. This process of extracting the elements of a collection is called collection unnesting. For example, you could roll up four quarterly sales tables into a yearly sales table. Specify a correlation name alias for the table, view, or subquery to be referenced elsewhere in the statement. Specify the name of a column of the object that is to be updated.

If column refers to a LOB object attribute, then you must first initialize it with a value of empty or null. You cannot update it with a literal. If column is part of the partitioning key of a partitioned table, then UPDATE will fail if you change a value in the column that would move the row to a different partition or subpartition, unless you enable row movement.

If this subquery refers to remote objects, then the UPDATE operation can run in parallel as long as the reference does not loop back to an object on the local database. If no default value for the corresponding column has been specified, then the database sets the column to null.

If you omit this clause, then the database updates all rows in the table or view. An OracleCommand used during an update operation to update records in the database that correspond to modified rows in the DataSet. It assumes you have already created an OracleConnection object. Instead, the UpdateCommand maintains a reference to the previously created OracleCommand object. During an update operation, if InsertCommand is not set and primary key information is present in the DataSet , you can use the OracleCommandBuilder class to automatically generate InsertCommand , and additional commands needed to reconcile the DataSet to the database.

The generation logic also requires key column information to be present in the DataSet. For more information see Generating Commands with CommandBuilders.