How to query synonyms in Oracle database

In Oracle database, synonyms are an important database object, which allow us to reference the same table or view in different databases, and can also simplify the writing of SQL query statements. This article explains how to query synonyms in an Oracle database.

1. View all synonyms

To view all synonyms in the Oracle database, you can use the following SQL statement:

SELECT owner, synonym_name, table_owner, table_name
FROM all_synonyms
ORDER BY owner, synonym_name;

Where owner represents the ownership of the synonym Or, synonym_name represents the name of the synonym, table_owner and table_name represent the owner and name of the table or view pointed by the synonym.

2. View the specified synonym

To view information about the table or view pointed to by a specified synonym, you can use the following SQL statement:

SELECT owner, table_name, table_type
FROM all_synonyms
WHERE synonym_name = 'synonym_name';

where , synonym_name represents the name of the synonym to be queried.

3. Query the object pointed to by the synonym

To query the information of the object pointed by a synonym, you can use the following SQL statement:

SELECT owner, table_name, table_type
FROM all_tables
WHERE table_name = (SELECT table_name FROM all_synonyms
                    WHERE owner = 'owner' AND synonym_name = 'synonym_name');

Among them, owner and synonym_name represent the owner and name of the synonym respectively.

4. Query the definition statement of synonyms

To query the definition statement of a synonym, you can use the following SQL statement:

SELECT dbms_metadata.get_ddl('SYNONYM', 'synonym_name', 'owner') AS synonym_ddl
FROM dual;

Among them, synonym_name and owner are respectively Represents the name and owner of the synonym.

5. Modify the object pointed to by a synonym

If you need to modify the object pointed to by a synonym, you can use the following SQL statement:

CREATE SYNONYM synonym_name FOR new_object;

Among them, synonym_name represents the The name of the modified synonym, new_object represents the new object to which the synonym should point.

The above is how to query synonyms in Oracle database. Correct understanding and use of synonyms can improve database maintenance efficiency and query performance.

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