Oracle – vb.net Oracle connection using TNS Name

SELECT owner, table_name
  FROM dba_tables

This is assuming that you have access to the DBA_TABLES data dictionary view. If you do not have those privileges but need them, you can request that the DBA explicitly grants you privileges on that table, or, that the DBA grants you the SELECT ANY DICTIONARY privilege or the SELECT_CATALOG_ROLE role (either of which would allow you to query any data dictionary table). Of course, you may want to exclude certain schemas like SYS and SYSTEM which have large numbers of Oracle tables that you probably don't care about.

Alternatively, if you do not have access to DBA_TABLES, you can see all the tables that your account has access to through the ALL_TABLES view:

SELECT owner, table_name
  FROM all_tables

Although, that may be a subset of the tables available in the database (ALL_TABLES shows you the information for all the tables that your user has been granted access to).

If you are only concerned with the tables that you own, not those that you have access to, you could use USER_TABLES:

SELECT table_name
  FROM user_tables

Since USER_TABLES only has information about the tables that you own, it does not have an OWNER column – the owner, by definition, is you.

Oracle also has a number of legacy data dictionary views-- TAB, DICT, TABS, and CAT for example-- that could be used. In general, I would not suggest using these legacy views unless you absolutely need to backport your scripts to Oracle 6. Oracle has not changed these views in a long time so they often have problems with newer types of objects. For example, the TAB and CAT views both show information about tables that are in the user's recycle bin while the [DBA|ALL|USER]_TABLES views all filter those out. CAT also shows information about materialized view logs with a TABLE_TYPE of "TABLE" which is unlikely to be what you really want. DICT combines tables and synonyms and doesn't tell you who owns the object.

from http://ora-12154.ora-code.com

ORA-12154: TNS:could not resolve the connect identifier specified
Cause: A connection to a database or other service was requested using a connect identifier, and the connect identifier specified could not be resolved into a connect descriptor using one of the naming methods configured. For example, if the type of connect identifier used was a net service name then the net service name could not be found in a naming method repository, or the repository could not be located or reached.
Action:

• If you are using local naming (TNSNAMES.ORA file):

• Make sure that "TNSNAMES" is listed as one of the values of the NAMES.DIRECTORY_PATH parameter in the Oracle Net profile (SQLNET.ORA)

• Verify that a TNSNAMES.ORA file exists and is in the proper directory and is accessible.

• Check that the net service name used as the connect identifier exists in the TNSNAMES.ORA file.

• Make sure there are no syntax errors anywhere in the TNSNAMES.ORA file. Look for unmatched parentheses or stray characters. Errors in a TNSNAMES.ORA file may make it unusable.

• If you are using directory naming:

• Verify that "LDAP" is listed as one of the values of the NAMES.DIRETORY_PATH parameter in the Oracle Net profile (SQLNET.ORA).

• Verify that the LDAP directory server is up and that it is accessible.

• Verify that the net service name or database name used as the connect identifier is configured in the directory.

• Verify that the default context being used is correct by specifying a fully qualified net service name or a full LDAP DN as the connect identifier

• If you are using easy connect naming:

• Verify that "EZCONNECT" is listed as one of the values of the NAMES.DIRETORY_PATH parameter in the Oracle Net profile (SQLNET.ORA).

• Make sure the host, port and service name specified are correct.

• Try enclosing the connect identifier in quote marks. See the Oracle Net Services Administrators Guide or the Oracle operating system specific guide for more information on naming.