Db2 Aliases Simplified Guide | Generated by AI
In IBM Db2, an alias is essentially an alternative name (a shortcut) for a database object, most often a table or view. It allows you to refer to an object using a different name than its base name, which can simplify queries, improve portability, or support application requirements.
Here’s how it works in practice:
1. Purpose of Aliases
- Simplify references: You can create an alias with a shorter or more convenient name.
- Schema transparency: If your application should not care which schema a table lives in, you can create an alias in your own schema that points to the base object in another schema.
- Portability: Applications referencing aliases don’t have to change if the underlying base object moves to another schema or even another database (in Db2 for z/OS, you can point to remote objects).
- Security & abstraction: Users can be given access to aliases rather than directly to base objects, hiding schema details.
2. Syntax
Basic syntax to create an alias:
CREATE ALIAS my_alias FOR schema_name.table_name;
Example:
CREATE ALIAS emp_alias FOR hr.employees;
Now you can query:
SELECT * FROM emp_alias WHERE dept = 'SALES';
3. Types of Aliases
- Simple table/view alias: Points to a table or view in the same or another schema.
- Remote alias (Db2 for z/OS): Can reference a table or view in another Db2 subsystem, enabling location transparency.
- Synonyms (older concept, mostly replaced by aliases): Db2 historically supported synonyms, but aliases are more flexible.
4. Key Characteristics
- Aliases don’t duplicate data—they just provide an alternative name.
- Dropping an alias does not affect the underlying table or view.
- Multiple aliases can point to the same object.
- Permissions on an alias may differ from the underlying table (depending on how you grant rights).
5. Alias vs Column/Table Aliasing in SQL
- The
CREATE ALIASstatement defines a permanent database object. - The
ASkeyword in aSELECTstatement (likeSELECT col1 AS c FROM mytable) is a query-level alias, temporary and only valid within that SQL statement.
👉 For example:
-- Permanent alias
CREATE ALIAS sales_q1 FOR accounting.sales_2025_q1;
-- Query-time alias
SELECT s.amount, s.date
FROM accounting.sales_2025_q1 AS s;
Would you like me to also explain the differences between Db2 aliases and views, since they’re often confused?