Editing Table Definitions 

Use

The Java Dictionary enables you to modify the definitions of tables that have been deployed to the database already. However, there are certain requirements and limitations that are introduced to prevent data loss and runtime problems when accessing the modified tables.

 

Prerequisites

You are in the Dictionary Perspective → Dictionary Explorer view of the SAP NetWeaver Developer Studio.

Activities

In the Java Dictionary you can perform the following modifications on tables that already exist in the database schema. All changes are applied to the tables in the database after you rebuild the project and re-deploy the Java Dictionary archive.

●      Delete a table

To mark a table as deleted in the Java Dictionary, open the context menu of the table and choose Delete Table.

You cannot reuse the name of a deleted table if you work in the Development Infrastructure. For local development you are not allowed to reuse the name in the relevant Dictionary project only.

●      Add columns

To add a new column at the end of the column list, choose Add Column in the Table Editor.

To insert a new column before a selected one, choose Insert Column.

When adding columns to a table, the column order may change. Therefore, we recommend that you do not rely on field sequence when accessing a table.

●      Change the type of a column

This option is DBMS-specific. If the new JDBC type of the column is incompatible with the original type, this may lead to a table conversion. A table conversion contains a data copy and therefore is a time-consuming operation. You should perform this change only if it is absolutely necessary.

●      Increase the length, change the DB default value, and the description of a column

●      Create an index

For more information, see Creating Indexes.

●      Set table buffering

For more information, see Buffering Type.

 

Decreasing the length of a column or deleting a new column can lead to a table conversion. A table conversion contains a data copy and can therefore needs a lot of time (especially during deployment in customer system during upgrade, if table already contains data there). You should make the change only if it is really necessary.

Renaming a column is equivalent to dropping a column and creating a similar column with a new name. This operation will lead to a loss of data of the content of the old column. The content of the new column will be empty.