Get only one row for each kind of a column

Question

hi there!
i have a little problem.
I have a table with 10 columns. One of them has repeated values. My goal is to get all the rows with this column only one time for each values that it has.
Ex:
Col1 Col2 Col3
A A A
B B B
C A C
D C D
Column 2 has repeated values. My goal is to get:
A A A
B B B
D C D
Only one time each value of column 2.
Thanks guys! ;)

Answer 1

SQL>  CREATE TABLE Tbl (col1 VARCHAR2(1),col2 VARCHAR2(1),col3 VARCHAR2(1));
Table created.
SQL> INSERT INTO Tbl VALUES ('A','A','A');
1 row created.
SQL>              INSERT INTO Tbl VALUES ('B','B','B');
1 row created.
SQL>              INSERT INTO Tbl VALUES ('C','A','C');
1 row created.
SQL>              INSERT INTO Tbl VALUES ('D','C','D');
1 row created.
SQL> commit;
Commit complete.
SQL> SELECT * FROM tbl t1
  2  WHERE
  3  rowid=(SELECT min(rowid)
  4         FROM tbl t2
  5         WHERE t1.col2=t2.col2);
C C C
A A A
B B B
D C D
SQL> SELECT * FROM tbl t1
  2  WHERE
  3  rowid=(SELECT max(rowid)
  4         FROM tbl t2
  5         WHERE t1.col2=t2.col2);
C C C
B B B
C A C
D C DEdited by: Saubhik on Aug 3, 2010 1:31 AM