Re[2]: [SQL] Query to eliminate duplicates

Hello Mario,

giovedì, 3 dicembre 98, you wrote:


MF> On 02-Dec-98 Sferacarta Software wrote:
>> MF> Is there a way to eliminate duplicate records using just SQL?
>>
>> SELECT DISTINCT ...

MF>         I deserved that!

MF>         The problem is that i have a table where there are duplicate records
MF> and i want to delete them! I tryed creating a unique index but it told me it
MF> couldn't because it didn't have a function to do something (I think it is
MF> because i had a boolean field in it)


select * from TABELA where COLUNA in (
     select COLUNA from TABELA group by COLUNA having 1 < count(COLUNA)
     );

This query should retrieve all rows where COLUNA field contains
duplicate values.
Unfortunately, seems it doesn't work on v6.4, but you may
do: select COLUNA from TABELA group by COLUNA having 1 < count(COLUNA)
to display only COLUNA field.

EXAMPLE:

select * from emp;
ename |empno|job       |  hiredate|sal      |comm|deptno|level| mgr
------+-----+----------+----------+---------+----+------+-----+----
ALLEN | 7499|SALESMAN  |1981-02-20|$1,600.00| 300|    20|    4|7782
BLAKE | 7698|MANAGER   |1981-05-01|$2,850.00|    |    30|    3|7782
JONES | 7900|CLERK     |1981-12-03|$950.00  |    |    30|    2|7782
MILLER| 7654|SALESMAN  |1981-09-28|$1,250.00| 400|    30|    3|7839
CLARK | 7844|SALESMAN  |1981-09-08|$1,500.00|    |    10|    2|7839
KING  | 7521|SALESMAN  |1981-02-22|$1,250.00| 500|    10|    1|7782
ALLEN | 7499|SALESMAN  |1981-02-20|$1,600.00| 300|    20|    4|7782
BLAKE | 7698|MANAGER   |1981-05-01|$2,850.00|    |    30|    3|7782
(8 rows)

select ename from emp group by ename having 1 < count(ename);
ename
-----
ALLEN
BLAKE
(2 rows)


-Jose'-