In my Oracle database, I have two tables T1 with primary key k1, and T2 with a composite primary key k1, k2. I would like to select all columns in T1 along with the number of lines in T2 such as T1.k1 = T2.k1.
It seems simple, but I can't figure how to use the COUNT function to get this result, any idea ?
I don't have your tables so I'll try to illustrate it using Scott's sample emp and dept tables:
SQL> select * from dept t1 order by t1.deptno;
DEPTNO DNAME LOC
---------- -------------- -------------
10 ACCOUNTING NEW YORK
20 RESEARCH DALLAS
30 SALES CHICAGO
40 OPERATIONS BOSTON
SQL> select deptno, empno, ename from emp order by deptno;
DEPTNO EMPNO ENAME
---------- ---------- ----------
10 7782 CLARK --> 3 employees in deptno 10
10 7839 KING
10 7934 MILLER
20 7566 JONES --> 5 employees in deptno 20
20 7902 FORD
20 7876 ADAMS
20 7369 SMITH
20 7788 SCOTT
30 7521 WARD --> 6 employees in deptno 30
30 7844 TURNER
30 7499 ALLEN
30 7900 JAMES
30 7698 BLAKE
30 7654 MARTIN
--> 0 employees in deptno 40
14 rows selected.
SQL>
A few options you might try:
Correlated subquery:
SQL> select t1.*,
2 (select count(*) from emp t2 where t2.deptno = t1.deptno) cnt
3 from dept t1
4 order by t1.deptno;
DEPTNO DNAME LOC CNT
---------- -------------- ------------- ----------
10 ACCOUNTING NEW YORK 3
20 RESEARCH DALLAS 5
30 SALES CHICAGO 6
40 OPERATIONS BOSTON 0
SQL>
(Outer) join with the COUNT function and the GROUP BY clause:
SQL> select t1.*, count(t2.rowid) cnt
2 from dept t1 left join emp t2 on t2.deptno = t1.deptno
3 group by t1.deptno, t1.dname, t1.loc
4 order by t1.deptno;
DEPTNO DNAME LOC CNT
---------- -------------- ------------- ----------
10 ACCOUNTING NEW YORK 3
20 RESEARCH DALLAS 5
30 SALES CHICAGO 6
40 OPERATIONS BOSTON 0
SQL>
(Outer) join with the COUNT function in its analytic form:
SQL> select distinct t1.*,
2 count(t2.rowid) over (partition by t1.deptno) cnt
3 from dept t1 left join emp t2 on t2.deptno = t1.deptno
4 order by t1.deptno;
DEPTNO DNAME LOC CNT
---------- -------------- ------------- ----------
10 ACCOUNTING NEW YORK 3
20 RESEARCH DALLAS 5
30 SALES CHICAGO 6
40 OPERATIONS BOSTON 0
SQL>
Related
I am making a join between 2 tables, where they bring me number_phone that have a relationship and I bring the times that these are repeated, however, I am trying to make a condition to the count, so that it only lists those that are repeated more than 4 times, I tried with having account and it brings me the counter all in null.
It is worth mentioning that I did not occupy group by for the count because it brought me wrong values.
SELECT
REPLACE(REPLACE(t.id_contrato,'0999',''),'0998','')as contrato ,
t.num_telefono,
conc.valor_actual,
(
SELECT COUNT('x')
FROM TBL_TELEFONO ct
WHERE ct.num_telefono = t.num_telefono
AND ct.origen_tel='TELEFONO CONTRATO'
-- HAVING COUNT(*) > 4
) as counter
FROM TBL_TELEFONO t
INNER JOIN CAM_TBL_ALERTA_CONCENTRADO conc ON t.num_telefono = conc.valor_actual
WHERE id_contrato IS NOT NULL
AND id_contrato NOT IN ('N/A')
ORDER BY 4 DESC
How can I list only those that are repeated more than 4 times?
I don't like debugging code with no sample data, so I'll try to illustrate it on Scott's sample EMP table. "Jobs" will act like your "telephone numbers".
SQL> select deptno, ename, job
2 from emp
3 order by job;
DEPTNO ENAME JOB
---------- ---------- ---------
20 SCOTT ANALYST --> 2 analysts
20 FORD ANALYST
10 MILLER CLERK --> 4 clerks
30 JAMES CLERK
20 SMITH CLERK
20 ADAMS CLERK
30 BLAKE MANAGER --> 3 managers
20 JONES MANAGER
10 CLARK MANAGER
10 KING PRESIDENT --> 1 president
30 TURNER SALESMAN --> 4 salesmen
30 MARTIN SALESMAN
30 WARD SALESMAN
30 ALLEN SALESMAN
14 rows selected.
SQL>
According to that, we'd like to fetch all clerks and salesmen as there are 4 (or more) of them.
Instead of count aggregate function, use count in its analytic form:
SQL> select deptno, ename, job,
2 count(*) over (partition by job) cnt
3 from emp
4 order by job;
DEPTNO ENAME JOB CNT
---------- ---------- --------- ----------
20 SCOTT ANALYST 2
20 FORD ANALYST 2
10 MILLER CLERK 4
30 JAMES CLERK 4
20 SMITH CLERK 4
20 ADAMS CLERK 4
30 BLAKE MANAGER 3
20 JONES MANAGER 3
10 CLARK MANAGER 3
10 KING PRESIDENT 1
30 TURNER SALESMAN 4
30 MARTIN SALESMAN 4
30 WARD SALESMAN 4
30 ALLEN SALESMAN 4
14 rows selected.
SQL>
Now things become easier: use that query as a CTE (or a subquery), and apply where clause:
SQL> with temp as
2 (select deptno, ename, job,
3 count(*) over (partition by job) cnt
4 from emp
5 )
6 select deptno, ename, job
7 from temp
8 where cnt >= 4
9 order by job;
DEPTNO ENAME JOB
---------- ---------- ---------
10 MILLER CLERK
30 JAMES CLERK
20 SMITH CLERK
20 ADAMS CLERK
30 TURNER SALESMAN
30 MARTIN SALESMAN
30 WARD SALESMAN
30 ALLEN SALESMAN
8 rows selected.
SQL>
Applied to your query (again, can't test it without any sample data):
with temp as
(select
replace(replace(t.id_contrato,'0999',''),'0998','')as contrato ,
t.num_telefono,
conc.valor_actual,
count(*) over (partition by t.num_telefono) as counter
from tbl_telefono t
inner join cam_tbl_alerta_concentrado conc on t.num_telefono = conc.valor_actual
where id_contrato is not null
and id_contrato not in ('N/A')
)
select contrato, num_telefono, valor_actual
from temp
where counter >= 4;
Join to the selection that have more than 4
SELECT
REPLACE(REPLACE(t.id_contrato,'0999',''),'0998','')as contrato ,
t.num_telefono,
conc.valor_actual,
ct.counter
FROM TBL_TELEFONO t
INNER JOIN (
SELECT num_telefono, COUNT(*) AS counter
FROM TBL_TELEFONO
WHERE origen_tel='TELEFONO CONTRATO'
GROUP BY num_telefono
HAVING COUNT(*) > 4
) ct
ON ct.num_telefono = t.num_telefono
INNER JOIN CAM_TBL_ALERTA_CONCENTRADO conc
ON t.num_telefono = conc.valor_actual
WHERE id_contrato IS NOT NULL
AND id_contrato NOT IN ('N/A')
ORDER BY ct.counter DESC
Wrap the query in another to return only where count > 4
select *
from (
<your query, but without order by>
) x
where count > 4
order by count desc
I was trying to print odd numbers of rows from my table without taking taking help of my numeric cloumns
when I try to execute this query I was getting only first row.
select * from emp3 where mod(rownum,2)=1;
emp3 is my table name.
and when I use my one of the numeric columns in place of rownum I was getting desired output.
select * from emp3 where mod(eid,2)=1 order by eid;
where eid is a numeric column in the table.
But what if do not have a numeric column and I want to print only odd number of rows from the table?
Help me!
Try to execute the below query
select * from (select rownum rn ,column from column_name) where mod(rn,2) <> 0
and please refer to this link for better understanding the concept of rownum https://www.youtube.com/watch?v=QMyw1jumGyQ
If the EID column isn't numeric, then use something that is. For example, ROW_NUMBER gives such an information:
SQL> with temp as
2 (select empno, ename, job sal,
3 row_number() over (order by null) rn
4 from emp
5 )
6 select *
7 from temp
8 where mod(rn, 2) = 1;
EMPNO ENAME SAL RN
---------- ---------- --------- ----------
7369 SMITH CLERK 1
7521 WARD SALESMAN 3
7654 MARTIN SALESMAN 5
7782 CLARK MANAGER 7
7839 KING PRESIDENT 9
7876 ADAMS CLERK 11
7902 FORD ANALYST 13
7 rows selected.
SQL>
Or even ROWNUM you already tried to use:
SQL> with temp as
2 (select empno, ename, job sal,
3 rownum rn
4 from emp
5 )
6 select *
7 from temp
8 where mod(rn, 2) = 1;
EMPNO ENAME SAL RN
---------- ---------- --------- ----------
7369 SMITH CLERK 1
7521 WARD SALESMAN 3
7654 MARTIN SALESMAN 5
7782 CLARK MANAGER 7
7839 KING PRESIDENT 9
7876 ADAMS CLERK 11
7902 FORD ANALYST 13
7 rows selected.
SQL>
I had a question with a single sql query related to an interactive table in apex
Here, look, I prescribe a request in which I print all the existing artists in the database, but I only have entries where all the fields have values, and those in which at least one NULL are not displayed
select artist.name as "Artist", country.name as "Country" , city.name as "City of foundation", label.name as "Label of records"
from artist, country, city, label
where artist.country = country_id
and artist.city = city_id
and city.country = country_id
and artist.label = label_id
How to fix it?
https://i.stack.imgur.com/ZRYzm.png
As you didn't provide test case (a screenshot isn't quite enough - at least, not to me), I'll try to show what might be going on using Scott's schema.
There are 4 departments: note department 40, and the fact that nobody works in it:
SQL> select * from dept;
DEPTNO DNAME LOC
---------- -------------- -------------
10 ACCOUNTING NEW YORK
20 RESEARCH DALLAS
30 SALES CHICAGO
40 OPERATIONS BOSTON
SQL> select * from emp where deptno = 40;
no rows selected
If you want to display all 4 departments and employees who work in them, you'd join EMP and DEPT table. Outer join lets you display department 40 (which, as we saw, has no employees):
SQL> select d.deptno, d.dname, e.ename
2 from dept d left join emp e on e.deptno = d.deptno --> outer join is here
3 order by d.deptno;
DEPTNO DNAME ENAME
---------- -------------- ----------
10 ACCOUNTING CLARK
10 ACCOUNTING MILLER
10 ACCOUNTING KING
20 RESEARCH JONES
20 RESEARCH SMITH
20 RESEARCH SCOTT
20 RESEARCH FORD
20 RESEARCH ADAMS
30 SALES WARD
30 SALES TURNER
30 SALES ALLEN
30 SALES JAMES
30 SALES MARTIN
30 SALES BLAKE
40 OPERATIONS --> this is what you're looking for
15 rows selected.
SQL>
You'd get the same result using the old Oracle's (+) outer join operator. You'd rather switch to modern joins and avoid that operator, though.
SQL> select d.deptno, d.dname, e.ename
2 from dept d, emp e
3 where d.deptno = e.deptno (+) --> the old outer join operator
4 order by d.deptno;
DEPTNO DNAME ENAME
---------- -------------- ----------
10 ACCOUNTING CLARK
10 ACCOUNTING MILLER
10 ACCOUNTING KING
20 RESEARCH JONES
20 RESEARCH SMITH
20 RESEARCH SCOTT
20 RESEARCH FORD
20 RESEARCH ADAMS
30 SALES WARD
30 SALES TURNER
30 SALES ALLEN
30 SALES JAMES
30 SALES MARTIN
30 SALES BLAKE
40 OPERATIONS
15 rows selected.
SQL>
I know how to delete duplicate records with ROWID.
Please guide me to delete duplicate records with ROWNUM in Oracle.
That just won't work. From documentation:
For each row returned by a query, the ROWNUM pseudocolumn returns a number indicating the order in which Oracle selects the row from a table or set of joined rows. The first row selected has a ROWNUM of 1, the second has 2, and so on.
Its value is set at the moment you run the query and can be changed, depending on how you fetch data (different ORDER BY will produce different ROWNUM value for the same row). As it is sequential, you can't set "groups" of ROWNUM values (for example, so that it goes from 1, 2, 3 for one set, then 1, 2, 3, 4, 5 for another - you'll always get 1, 2, 3, 4, 5, 6, 7, 8).
If you planned to do something like this:
SQL> create table test as
2 select e.empno, e.deptno, d.dname, e.ename
3 from emp e join dept d on e.deptno = d.deptno;
Table created.
SQL> select * from test order by deptno;
EMPNO DEPTNO DNAME ENAME
---------- ---------- -------------- ----------
7782 10 ACCOUNTING CLARK
7839 10 ACCOUNTING KING
7934 10 ACCOUNTING MILLER
7369 20 RESEARCH SMITH
7902 20 RESEARCH FORD
7566 20 RESEARCH JONES
7900 30 SALES JAMES
7844 30 SALES TURNER
7654 30 SALES MARTIN
7521 30 SALES WARD
7499 30 SALES ALLEN
7698 30 SALES BLAKE
12 rows selected.
SQL> delete from test t
2 where t.empno in (select a.empno
3 from (select t1.empno, t1.deptno, t1.dname, rownum rn
4 from test t1
5 ) a
6 where a.rn > 1
7 );
11 rows deleted.
As you can see, all rows (but one) are duplicates. Here's why:
SQL> rollback;
Rollback complete.
SQL> select a.deptno, a.empno, a.rn, a.rn1
2 from (select t1.empno, t1.deptno, t1.dname, rownum rn,
3 row_number() over (partition by t1.deptno order by null) rn1
4 from test t1
5 ) a;
DEPTNO EMPNO RN RN1
---------- ---------- ---------- ----------
10 7782 2 1
10 7839 1 2
10 7934 3 3
20 7369 5 1
20 7902 4 2
20 7566 6 3
30 7900 7 1
30 7844 8 2
30 7654 9 3
30 7521 10 4
30 7499 11 5
30 7698 12 6
12 rows selected.
See? RN (ROWNUM) has all values from 1, 2, ..., 12. RN1 (ROW_NUMBER, which allows us to set partitions) does the job correctly. So, if you used RN1 instead of RN, it would work:
SQL> delete from test t
2 where t.empno in (select a.empno
3 from (select t1.empno, t1.deptno, t1.dname, rownum rn,
4 row_number() over (partition by t1.deptno order by null) rn1
5 from test t1
6 ) a
7 where a.rn1 > 1
8 );
9 rows deleted.
SQL> select * From test;
EMPNO DEPTNO DNAME ENAME
---------- ---------- -------------- ----------
7782 10 ACCOUNTING CLARK
7369 20 RESEARCH SMITH
7900 30 SALES JAMES
SQL>
[EDIT: deleting duplicates #2]
Here's another example which shows how/what to do if you want to delete duplicates. It is based on the "ROWID technique" (although there are another ones too).
Back to the table we've been working with. Suppose that we want to keep only one distinct job per department:
SQL> select deptno, job, dname, empno, ename
2 from test
3 order by deptno, job;
DEPTNO JOB DNAME EMPNO ENAME
---------- --------- -------------- ---------- ----------
10 CLERK ACCOUNTING 7934 MILLER
10 MANAGER ACCOUNTING 7782 CLARK
10 PRESIDENT ACCOUNTING 7839 KING
20 ANALYST RESEARCH 7902 FORD
20 CLERK RESEARCH 7369 SMITH
20 MANAGER RESEARCH 7566 JONES
30 CLERK SALES 7900 JAMES
30 MANAGER SALES 7698 BLAKE
30 SALESMAN SALES 7844 TURNER -- leave
30 SALESMAN SALES 7654 MARTIN -- only
30 SALESMAN SALES 7521 WARD -- one
30 SALESMAN SALES 7499 ALLEN -- salesman
12 rows selected.
in department 10, there are no duplicates - 3 employees, each of them doing their own job
the same goes for department 20
however, in department 30, there are 4 SALESMEN and we want to keep only one - another ones are duplicates
It means that you have to take both columns - DEPTNO and JOB - into account when deleting rows. Let's do that:
SQL> delete from test a
2 where rowid > (select min(rowid)
3 from test b
4 where a.deptno = b.deptno --> take both DEPTNO ...
5 and a.job = b.job --> and JOB into account
6 );
3 rows deleted.
The result: departments 10 and 20 didn't change, but in department 30 now we have only one salesman, just as we wanted:
SQL> select deptno, job, dname, empno, ename
2 from test
3 order by deptno, job;
DEPTNO JOB DNAME EMPNO ENAME
---------- --------- -------------- ---------- ----------
10 CLERK ACCOUNTING 7934 MILLER
10 MANAGER ACCOUNTING 7782 CLARK
10 PRESIDENT ACCOUNTING 7839 KING
20 ANALYST RESEARCH 7902 FORD
20 CLERK RESEARCH 7369 SMITH
20 MANAGER RESEARCH 7566 JONES
30 CLERK SALES 7900 JAMES
30 MANAGER SALES 7698 BLAKE
30 SALESMAN SALES 7844 TURNER
9 rows selected.
SQL>
I’m running into a problem.
Say, I have columns called “C1, C2, C3....” in a table. I’d like to use the longest string in C1 to replace every other cells in C1 column without disturbing other columns.
I tired several ways but I cannot get my Oracle code run. Could someone please show me a sample code to do this problem? I typed my question using a cellphone so I apologize for not showing you my code. But I think my description is fine... Thank you!
I would use window functions. Oracle has a very convenient functionality with keep:
select max(col1) keep (dense_rank first order by len(col1) desc) over () as col1,
col2, col3, . . .
from t;
You can incorporate this into an update:
update t
set col1 = (select select max(col1) keep (dense_rank first order by len(col1) desc) over () as col1
from t
);
For example:
SQL> select * from test;
DEPTNO DNAME LOC
---------- -------------- -------------
10 ACCOUNTING NEW YORK
20 RESEARCH DALLAS
30 SALES CHICAGO
40 OPERATIONS BOSTON
SQL> update test set
2 dname = (select max(dname) --> MAX fixes TOO-MANY-ROWS because ACCOUNTING
3 from test -- and OPERATIONS have same length
4 where length(dname) = (select max(length(dname))
5 from test
6 )
7 );
4 rows updated.
SQL> select * from test;
DEPTNO DNAME LOC
---------- -------------- -------------
10 OPERATIONS NEW YORK
20 OPERATIONS DALLAS
30 OPERATIONS CHICAGO
40 OPERATIONS BOSTON
SQL>
[EDIT, GROUP BY]
Another example is based on a different table, which reflects what you described in a comment. The DEPTNO (department number) is used to "group" employees, and I'm going to update the JOB column value to the longest job name within that department.
Query is similar to the previous one; it just joins appropriate columns (DEPTNO) throughout code.
Sample data:
SQL> select * from test order by deptno, ename;
DEPTNO ENAME JOB
---------- ---------- ---------
10 CLARK MANAGER
KING PRESIDENT --> the longest in DEPTNO = 10
MILLER CLERK
20 ADAMS CLERK
FORD ANALYST
JONES MANAGER --> as long as ANALYST, but MAX(JOB) will return this value
SCOTT ANALYST
SMITH CLERK
30 ALLEN SALESMAN --> the longest in DEPTNO = 30
BLAKE MANAGER
JAMES CLERK
MARTIN SALESMAN
TURNER SALESMAN
WARD SALESMAN
Update and the result:
SQL> update test t set
2 t.job = (select max(t1.job)
3 from test t1
4 where t1.deptno = t.deptno
5 and length(t1.job) = (select max(length(t2.job))
6 from test t2
7 where t2.deptno = t1.deptno
8 )
9 );
14 rows updated.
SQL> select * from test order by deptno, ename;
DEPTNO ENAME JOB
---------- ---------- ---------
10 CLARK PRESIDENT
KING PRESIDENT
MILLER PRESIDENT
20 ADAMS MANAGER
FORD MANAGER
JONES MANAGER
SCOTT MANAGER
SMITH MANAGER
30 ALLEN SALESMAN
BLAKE SALESMAN
JAMES SALESMAN
MARTIN SALESMAN
TURNER SALESMAN
WARD SALESMAN