Question

I have a mySQL query to get columns from a table like this:

String sqlStr="select column_name 
from information_schema.COLUMNS 
where table_name='users' 
and table_schema='"+_db+"' 
and column_name not in ('password','version','id')"

How do I change the above query in Oracle 11g database? I need to get columns names as a resultset for table ‘users’ excluding certain columns, specifying a schema. Right now I have all tables in my new tablespace, so do I specify tablespace name in place of schema name?

Also is there a generic HQL for this? In my new Oracle database (I am new to Oracle), I only have tablespace name, so is that equivalent to schema name (logically?)

Answer 1

The Oracle equivalent for information_schema.COLUMNS is USER_TAB_COLS for tables owned by the current user, ALL_TAB_COLS or DBA_TAB_COLS for tables owned by all users.

Tablespace is not equivalent to a schema, neither do you have to provide the tablespace name.

Providing the schema/username would be of use if you want to query ALL_TAB_COLS or DBA_TAB_COLS for columns OF tables owned by a specific user. in your case, I’d imagine the query would look something like:

String sqlStr= "
SELECT column_name
  FROM all_tab_cols
 WHERE table_name = 'USERS'
   AND owner = '" +_db+ "'
   AND column_name NOT IN ( 'PASSWORD', 'VERSION', 'ID' )"

Note that with this approach, you risk SQL injection.

EDIT: Uppercased the table- and column names as these are typically uppercase in Oracle; they are only lower- or mixed case if created with double quotes around them.