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Summary of Alter Statement Restrictions

Statement Type

DBMS

Restriction

INSERT SELECT

All

You must include a default value or initial value for all new columns that are NOT NULL, otherwise the INSERT SELECT statement fails.

INSERT SELECT

Oracle

You cannot use the LONG/LONG VARCHAR datatype in an INSERT SELECT statement. As a result, reloading data from a temporary table that contains a column with a LONG/LONG VARCHAR datatype fails.

FK and/or ADD CHECK

All

If the database supports the creation of foreign key or CHECK constraints without applying them to existing data, the data may not conform to data integrity rules after running the modify script. Warning messages are displayed for changes that can affect data integrity.

ADD CHECK

SQL Server, SAP ASE

In some database systems, you cannot modify a column CHECK constraint using an alter statement. The ALTER ADD CHECK statement can only add CHECK constraints at the table level. In this case, when you add a column CHECK constraint, you will generate DROP and CREATE statements for the tables that include the new CHECK constraint. To avoid dropping and recreating the table, you can specify the constraint at the table level.

FK

DB2 z/OS

If you add a foreign key to a table with data, DB2 z/OS sets the tablespace containing the table to the check pending state. You must run the CHECK utility to reset the tablespace status before using the table.

ALTER TABLE

Informix

Although Informix supports moving columns within a table using the ALTER TABLE statement, erwin Data Modeler moves columns using DROP TABLE/CREATE TABLE statements.