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Columns Collection

Questa caratteristica verrà rimossa a partire da una delle prossime versioni di Microsoft SQL Server. Evitare di utilizzare questa funzionalità in un nuovo progetto di sviluppo e prevedere interventi di modifica nelle applicazioni in cui è attualmente implementata.

The Columns collection contains Column objects that expose the columns of a Microsoft SQL Server table.

Modello di oggetti SQL-DMO in cui è visualizzato l'oggetto corrente

Osservazioni

With the Columns collection, you can:

  • Add a column to a SQL Server table.

  • Remove a column from a SQL Server table.

Columns in SQL Server tables are defined as part of a CREATE TABLE or ALTER TABLE statement.

When creating a SQL Server table using the Table object, an empty Columns collection is created as part of the Table object creation. Adding Column objects to the Columns collection adds column definition text to the CREATE TABLE statement generated when the Table object is added to the Tables collection of a Database object.

If a Table object references an existing SQL Server table, changes to the Columns collection generate ALTER TABLE statements.

For more information about creating columns, see Column Object.

To remove a column from a SQL Server table

  1. Get the desired Table object from the Tables collection of a Database object.

  2. Use the BeginAlter method of the Table object to mark the beginning of changes to the SQL Server table.

  3. Use the Remove method of the Columns collection of a Table object. Indicate the targeted column using the column name or the ordinal location in the collection, as in:

    oTables("Employees").Columns.Remove("Photo")

  4. Use the DoAlter method of the Table object to submit the changed table definition to SQL Server.

    [!NOTA]

    Dropping a column from a SQL Server table is bound by dependencies on the column, and can fail.