Updating Databases

These exercises show you how to insert rows, cancel and confirm changes, and delete data.

• Adding Rows To a Table
  Use the INSERT statement to add data about a new department.
• Making Changes Permanent
  Use the COMMIT statement to make all changes permanent.
• Ensuring Data Consistency
  Sybase IQ has special features that ensure data consistency in a data warehouse environment.
• Savepoints
  To limit the amount of data that Sybase IQ writes to disk, set a savepoint. Savepoints define a point in a transaction after which all changes can be undone by a ROLLBACK TO SAVEPOINT statement. This allows you to commit data before the entire transaction finishes.
• Updating Multiple Tables From Multiple Accounts
  If you are working on several tables within one database, Sybase IQ allows multiple readers and writers in a database, as long as the writers write to different tables.
• Deleting Rows
  Sometimes you will want to remove rows from a table.
• Updating Rows
  Other times, you may want to change certain rows based on the value of a particular column. The SET clause specifies the columns to update and their new values, and the WHERE clause specifies the rows to update.
• Synchronizing Join Indexes
  While you update a table that is involved in a join index, that join index is unavailable to other writers. Sybase IQ lets you control when it updates join indexes, because such updates may take a lot of time depending on the order of updates to various tables referenced by the indexes.