SELECT * FROM USER_TAB_COLS WHERE TABLE_NAME = 'my_table';
SELECT * FROM ALL_TAB_COLS WHERE TABLE_NAME = 'my_table';
SELECT * FROM DBA_TAB_COLS WHERE TABLE_NAME = 'my_table';
SELECT * FROM USER_TAB_COLUMNS WHERE COLUMN_NAME = 'MY_COLUMN'; -- Connected user
SELECT * FROM ALL_TAB_COLUMNS WHERE COLUMN_NAME = 'MY_COLUMN'; -- Other schemas
SELECT * FROM DBA_TAB_COLUMNS WHERE COLUMN_NAME = 'MY_COLUMN'; -- All tables