Hi is it possible to retrieve the primary key and unique key using the dba_tab_cols query?
Is there any query that allows me to retrieve all of the following fields?
Column Name
Data Type
Primary Key
Null/Not Null
Unique Key
Default Value
Extra
Both primary and unique keys can span more than one column, so they wouldn't belong in dba_tab_columns. You'd need to look at dba_constraints and dba_cons_columns to get that information.
This is a starting point, maybe:
select owner, table_name, column_name, data_type, primary_key,
nullable, unique_key, data_default
from (
select dtc.owner, dtc.table_name, dtc.column_id, dtc.column_name,
dtc.data_type, dtc.nullable, dtc.data_default,
case when dc.constraint_type = 'P' and dcc.column_name = dtc.column_name
then dc.constraint_name end as primary_key,
case when dc.constraint_type = 'U' and dcc.column_name = dtc.column_name
then dc.constraint_name end as unique_key,
row_number() over (partition by dtc.owner, dtc.table_name, dtc.column_id
order by null) as rn
from dba_tab_columns dtc
left join dba_constraints dc
on dc.owner = dtc.owner
and dc.table_name = dtc.table_name
and dc.constraint_type in ('P', 'U')
left join dba_cons_columns dcc
on dcc.owner = dc.owner
and dcc.constraint_name = dc.constraint_name
and dcc.table_name = dc.table_name
and dcc.column_name = dtc.column_name
where dtc.owner = '<owner>'
and dtc.table_name = '<table_name>'
)
where rn = 1
order by owner, table_name, column_id;
I've done this with a subquery that generates a row_number value because you'd get duplicates for a table with more than one constraint; and because you want the default value, which is a long (column data_default), you can't use distinct or group by. It feels a bit inelegant, but I'm sure you can work on it to get what you need.
It's also possible to have a check constraint that replicates the not null version, though it isn't advisable. And a unique index won't show up as a unique constraint, so you might want to look for one of those too, via dba_indexes and dba_ind_columns. An index used to back up a unique constrain will appear in both, though.
You could look at dbms_metadata.get_ddl to get this information too, depending on what you intend to do with it. I'm not sure why this would be useful, other than to try to recreate the schema elsewhere, and there are better tools for doing that.
Related
Currently I am trying to find all the unique indexes defined in a table which are NOT NULL for Oracle database. What I mean by that is, Oracle allows creating unique indexes on columns which are even defined as NULL.
So if my table has two unique indexes, I want to retrieve the particular unique index which is having all the columns having the NOT NULL constraints.
I did come up with this query:
select ind.index_name, ind_col.column_name, ind.index_type, ind.uniqueness
from sys.dba_indexes ind
inner join sys.dba_ind_columns ind_col on ind.owner = ind_col.index_owner and ind.index_name = ind_col.index_name
where ind.owner in ('ISADRM') and ind.table_name in ('TH_RHELOR') and ind.uniqueness IN ('UNIQUE')
The above query is giving me all the unique indexes with the associated columns, but I am not sure, how should I join the above query with ALL_TAB_COLS which has the NULLABILITY data for all the columns of a table.
I tried joining this table with indexes and tried subquery as well, but not getting appropriate results.
Hence, would request you to please comment on same.
Analytic functions and inline views can help.
The analytic functions let you return detailed data but also create a summary on that data, based on separate windows. The detailed results include index owner, index name, and column name, but the counts are only per index owner and index name.
The first inline view joins the three tables, returns the detailed information, and has analytic functions to generate the count of all columns and the count of all nullable columns. The second inline view only selects rows where those two counts are equal.
--Unique indexes and columns where every column is NOT NULL.
select owner, index_name, column_name
from
(
--All relevant columns and counts of columns and not null columns.
select
dba_indexes.owner,
dba_indexes.index_name,
dba_tab_columns.column_name,
dba_tab_columns.nullable,
count(*) over (partition by dba_indexes.owner, dba_indexes.index_name) total_columns,
sum(case when nullable = 'N' then 1 else 0 end)
over (partition by dba_indexes.owner, dba_indexes.index_name) total_not_null_columns
from dba_indexes
join dba_ind_columns
on dba_indexes.owner = dba_ind_columns.index_owner
and dba_indexes.index_name = dba_ind_columns.index_name
join dba_tab_columns
on dba_ind_columns.table_name = dba_tab_columns.table_name
and dba_ind_columns.column_name = dba_tab_columns.column_name
where dba_indexes.owner = user
and dba_indexes.uniqueness = 'UNIQUE'
order by 1,2,3
)
where total_columns = total_not_null_columns
order by 1,2,3;
Analytic functions and inline views are tricky but they're very powerful once you learn how to use them.
I have used this query to fetch the list of sequences belonging to an Oracle database user:
SELECT * FROM all_sequences x,all_tables B
WHERE x.sequence_owner=B.owner AND B.TABLE_NAME='my_table';
But that database user is having many more sequence also, so the query returns me all the sequence of the database user. Can anybody help me to find the particular sequence of my_table using query so that I can get the auto increment id in my application.
i want the query which fetch list of table of my database user with the sequence and triggers used in the table
You can get the triggers associated with your tables from the user_triggers view. You can then look for any dependencies recorded for those triggers in user_dependencies, which may include objects other than sequences (packages etc.), so joining those dependencies to the user_sequences view will only show you the ones you are interested in.
Something like this, assuming you are looking at your own schema, and you're only interesting in triggers that references sequences (which aren't necessarily doing 'auto increment', but are likely to be):
select tabs.table_name,
trigs.trigger_name,
seqs.sequence_name
from user_tables tabs
join user_triggers trigs
on trigs.table_name = tabs.table_name
join user_dependencies deps
on deps.name = trigs.trigger_name
join user_sequences seqs
on seqs.sequence_name = deps.referenced_name;
SQL Fiddle demo.
If you're actually looking at a different schema then you'll need to use all_tables etc. and filter and join on the owner column for the user you're looking for. And if you want to include tables which don't have triggers, or triggers which don't refer to sequences, you can use outer joins.
Version looking for a different schema, though this assumes you have the privs necessary to access the data dictionary information - that the tables etc. are visible to you, which they may not be:
select tabs.table_name,
trigs.trigger_name,
seqs.sequence_name
from all_tables tabs
join all_triggers trigs
on trigs.table_owner = tabs.owner
and trigs.table_name = tabs.table_name
join all_dependencies deps
on deps.owner = trigs.owner
and deps.name = trigs.trigger_name
join all_sequences seqs
on seqs.sequence_owner = deps.referenced_owner
and seqs.sequence_name = deps.referenced_name
where tabs.owner = '<owner>';
If that can't see them then you might need to look at the DBA views, again if you have sufficient privs:
select tabs.table_name,
trigs.trigger_name,
seqs.sequence_name
from dba_tables tabs
join dba_triggers trigs
on trigs.table_owner = tabs.owner
and trigs.table_name = tabs.table_name
join dba_dependencies deps
on deps.owner = trigs.owner
and deps.name = trigs.trigger_name
join dba_sequences seqs
on seqs.sequence_owner = deps.referenced_owner
and seqs.sequence_name = deps.referenced_name
where tabs.owner = '<owner>';
One way would be to run these queries to check if there are any sequence's Pseudocolumns (NEXTVAL and CURRVAL ) used in your functions , procedures, packages, Triggers or PL/SQL JAVA SOURCE.
select * from user_source where
UPPER(TEXT) LIKE '%NEXTVAL%';
select * from all_source where
UPPER(TEXT) LIKE '%NEXTVAL%';
Then go to the specific Procedure, Function or Trigger to check which column/table gets populated by a sequence.
The query could also be used with '%CURRVAL%'
This might not help if you are running inserts from JDBC or other external applications using a sequence.
Oracle 12c introduced the IDENTITY columns, using which you could create a table with an identity column, which is generated by default.
CREATE TABLE t1 (c1 NUMBER GENERATED BY DEFAULT ON NULL AS IDENTITY,
c2 VARCHAR2(10));
This will internally create a sequence that auto-generates the value for the table's column.So, If you would like to know which sequence generates the value for which table, you may query the all_tab_columns
SELECT data_default AS sequence_val
,table_name
,column_name
FROM all_tab_columns
WHERE OWNER = 'HR'
AND identity_column = 'YES';
SEQUENCE_VAL |TABLE_NAME |COLUMN_NAME
-----------------------------------------|-------------------------------------
"HR"."ISEQ$$_78160".nextval |T1 |C1
I found a solution to this problem to guess the sequence of a particular sequence
select * from SYS.ALL_SEQUENCES where SEQUENCE_OWNER='OWNER_NAME' and LAST_NUMBER between (select max(FIELD_NAME) from TABLE_NAME) and (select max(FIELD_NAME)+40 from TABLE_NAME);
This query will guess by search the LAST_NUMBER of the sequence value between MAX value of the field using sequence and Max value + 40 (in my case cache value is 20, so I put 40)
select SEQUENCE_NAME from sys.ALL_TAB_IDENTITY_COLS where owner = 'SCHEMA_NAME' and table_name = 'TABLE_NAME';
How can I reference a column outside of a subquery using Oracle? I specifically need to use it in the WHERE statement of the subquery.
Basically I have this:
SELECT Item.ItemNo, Item.Group
FROM Item
LEFT OUTER JOIN (SELECT Attribute.Group, COUNT(1) CT
FROM Attribute
WHERE Attribute.ItemNo=12345) A ON A.Group = Item.Group
WHERE Item.ItemNo=12345
I'd like to change WHERE Attribute.ItemNo=12345 to WHERE Attribute.ItemNo=Item.ItemNo in the subquery, but I can't figure out if this is possible. I keep getting "ORA-00904: 'Item'.'ItemNo': Invalid Identifier"
EDIT:
Ok, this is why I need this kind of structure:
I want to be able to get a count of the "Error" records (where the item is missing a value) and the "OK" records (where the item has a value).
The way I have set it up in the fiddle returns the correct data. I think I might just end up filling in the value in each of the subqueries, since this would probably be the easiest way. Sorry if my data structures are a little convoluted. I can explain if need be.
My tables are:
create table itemcountry(
itemno number,
country nchar(3),
imgroup varchar2(10),
imtariff varchar2(20),
exgroup varchar2(10),
extariff varchar2(20) );
create table itemattribute(
attributeid varchar2(10),
tariffgroup varchar2(10),
tariffno varchar2(10) );
create table icav(
itemno number,
attributeid varchar2(10),
value varchar2(10) );
and my query so far is:
select itemno, country, imgroup, imtariff, im.error "imerror", im.ok "imok", exgroup, extariff, ex.error "exerror", ex.ok "exok"
from itemcountry
left outer join (select sum(case when icav.itemno is null then 1 else 0 end) error, sum(case when icav.itemno is not null then 1 else 0 end) ok, tariffgroup, tariffno
from itemattribute ia
left outer join icav on ia.attributeid=icav.attributeid
where (icav.itemno=12345 or icav.itemno is null)
group by tariffgroup, tariffno) im on im.tariffgroup=imgroup and imtariff=im.tariffno
left outer join (select sum(case when icav.itemno is null then 1 else 0 end) error, sum(case when icav.itemno is not null then 1 else 0 end) ok, tariffgroup, tariffno
from itemattribute ia
left outer join icav on ia.attributeid=icav.attributeid
where (icav.itemno=12345 or icav.itemno is null)
group by tariffgroup, tariffno) ex on ex.tariffgroup=exgroup and extariff=ex.tariffno
where itemno=12345;
It's also set up in a SQL Fiddle.
You can do it in a sub-query but not in a join. In your case I don't see any need to. You can put it in the join condition.
select i.itemno, i.group
from item i
left outer join ( select group, itemno
from attribute b
group by group itemno ) a
on a.group = i.group
and i.itemno = a.itemno
where i.itemno = 12345
The optimizer is built to deal with this sort of situation so utilise it!
I've changed the count(1) to a group by as you need to group by all columns that aren't aggregated.
I'm assuming that your actual query is more complicated than this as with the columns you're selecting this is probably equivilent to
select itemno, group
from item
where itemno = 12345
You could also write your sub-query with an analytic function instead. Something like count(*) over ( partition by group).
As an aside using a keyword as a column name, in this case group is A Bad Idea TM. It can cause a lot of confusion. As you can see from the code above you have a lot of groups in there.
So, based on your SQL-Fiddle, which I've added to the question I think you're looking for something like the following, which doesn't look much better. I suspect, given time, I could make it simpler. On another side note explicitly lower casing queries is never worth the hassle it causes. I've followed your naming convention though.
with sub_query as (
select count(*) - count(icav.itemno) as error
, count(icav.itemno) as ok
, min(itemno) over () as itemno
, tariffgroup
, tariffno
from itemattribute ia
left outer join icav
on ia.attributeid = icav.attributeid
group by icav.itemno
, tariffgroup
, tariffno
)
select ic.itemno, ic.country, ic.imgroup, ic.imtariff
, sum(im.error) as "imerror", sum(im.ok) as "imok"
, ic.exgroup, ic.extariff
, sum(ex.error) as "exerror", sum(ex.ok) as "exok"
from itemcountry ic
left outer join sub_query im
on ic.imgroup = im.tariffgroup
and ic.imtariff = im.tariffno
and ic.itemno = im.itemno
left outer join sub_query ex
on ic.exgroup = ex.tariffgroup
and ic.extariff = ex.tariffno
and ic.itemno = ex.itemno
where ic.itemno = 12345
group by ic.itemno, ic.country
, ic.imgroup, ic.imtariff
, ic.exgroup, ic.extariff
;
You can put WHERE attribute.itemno=item.itemno inside the subquery. You are going to filter the data anyway, filtering the data inside the subquery is usually faster too.
Recently I fixed the some bug: there was rownum in the join condition.
Something like this: left join t1 on t1.id=t2.id and rownum<2. So it was supposed to return only one row regardless of the “left join”.
When I looked further into this, I realized that I don’t understand how Oracle evaluates rownum in the "left join" condition.
Let’s create two sampe tables: master and detail.
create table MASTER
(
ID NUMBER not null,
NAME VARCHAR2(100)
)
;
alter table MASTER
add constraint PK_MASTER primary key (ID);
prompt Creating DETAIL...
create table DETAIL
(
ID NUMBER not null,
REF_MASTER_ID NUMBER,
NAME VARCHAR2(100)
)
;
alter table DETAIL
add constraint PK_DETAIL primary key (ID);
alter table DETAIL
add constraint FK_DETAIL_MASTER foreign key (REF_MASTER_ID)
references MASTER (ID);
prompt Disabling foreign key constraints for DETAIL...
alter table DETAIL disable constraint FK_DETAIL_MASTER;
prompt Loading MASTER...
insert into MASTER (ID, NAME)
values (1, 'First');
insert into MASTER (ID, NAME)
values (2, 'Second');
commit;
prompt 2 records loaded
prompt Loading DETAIL...
insert into DETAIL (ID, REF_MASTER_ID, NAME)
values (1, 1, 'REF_FIRST1');
insert into DETAIL (ID, REF_MASTER_ID, NAME)
values (2, 1, 'REF_FIRST2');
insert into DETAIL (ID, REF_MASTER_ID, NAME)
values (3, 1, 'REF_FIRST3');
commit;
prompt 3 records loaded
prompt Enabling foreign key constraints for DETAIL...
alter table DETAIL enable constraint FK_DETAIL_MASTER;
set feedback on
set define on
prompt Done.
Then we have this query :
select * from master t
left join detail d on d.ref_master_id=t.id
The result set is predictable: we have all the rows from the master table and 3 rows from the detail table that matched this condition d.ref_master_id=t.id.
Result Set
Then I added “rownum=1” to the join condition and the result was the same
select * from master t
left join detail d on d.ref_master_id=t.id and rownum=1
The most interesting thing is that I set “rownum<-666” and got the same result again!
select * from master t
left join detail d on d.ref_master_id=t.id and rownum<-666.
Due to the result set we can say that this condition was evaluated as “True” for 3 rows in the detail table. But if I use “inner join” everything goes as supposed to be.
select * from master t
join detail d on d.ref_master_id=t.id and rownum<-666.
This query doesn’t return any row,because I can't imagine rownum to be less then -666 :-)
Moreover, if I use oracle syntax for outer join, using “(+)” everything goes well too.
select * from master m ,detail t
where m.id=t.ref_master_id(+) and rownum<-666.
This query doesn’t return any row too.
Can anyone tell me, what I misunderstand with outer join and rownum?
ROWNUM is a pseudo-attribute of result sets, not of base tables. ROWNUM is defined after rows are selected, but before they're sorted by an ORDER BY clause.
edit: I was mistaken in my previous writeup of ROWNUM, so here's new information:
You can use ROWNUM in a limited way in the WHERE clause, for testing if it's less than a positive integer only. See ROWNUM Pseudocolumn for more details.
SELECT ... WHERE ROWNUM < 10
It's not clear what value ROWNUM has in the context of a JOIN clause, so the results may be undefined. There seems to be some special-case handling of expressions with ROWNUM, for instance WHERE ROWNUM > 10 always returns false. I don't know how ROWNUM<-666 works in your JOIN clause, but it's not meaningful so I would not recommend using it.
In any case, this doesn't help you to fetch the first detail row for each given master row.
To solve this you can use analytic functions and PARTITION, and combine it with Common Table Expressions so you can access the row-number column in a further WHERE condition.
WITH numbered_cte AS (
SELECT *, ROW_NUMBER() OVER (PARTITION BY t.id ORDER BY d.something) AS rn
FROM master t LEFT OUTER JOIN detail d ON d.ref_master_id = t.id
)
SELECT *
FROM numbered_cte
WHERE rn = 1;
if you want to get the first three values from the join condition change the select statement like this.
select *
from (select *
from master t left join detail d on d.ref_master_id=t.id)
where rownum<3;
You will get the required output. Take care on unambigiously defined column names when using *
Let me give an absolute answer which u can run directly with out making any changes to the code.
select *
from (select t.id,t.name,d.id,d.ref_master_id,d.name
from master t left join detail d on d.ref_master_id=t.id)
where rownum<3;
A ROWNUM filter doesn't make any sense in a join, but it isn't being rejected as invalid.
The explain plan will either include the ROWNUM filter or exclude it. If it includes it, it will apply the filter to the detail table after applying the other join condition(s). So if you put in ROWNUM=100 (which will never be satisfied) all the detail rows are excluded and then the outer join kicks in.
If you put in ROWNUM=1 it seems to drop the filter.
And if you query
with
a as (select rownum a_val from dual connect by level < 10),
b as (select rownum*2 b_val from dual connect by level < 10)
select * from a left join b on a_val < b_val and rownum in (1,3);
you get something totally weird.
It probably should be rejected as an error, so expect nonsensical things to happen
I am attempting to figure out if a column in Oracle is populated from a sequence. My impression of how Oracle handles sequencing is that the sequence and column are separate entities and one needs to either manually insert the next sequence value like:
insert into tbl1 values(someseq.nextval, 'test')
or put it into a table trigger. Meaning that it is non-trivial to tell if a column is populated from a sequence. Is that correct? Any ideas about how I might go about figuring out if a column is populated from a sequence?
You are correct; the sequence is separate from the table, and a single sequence can be used to populate any table, and the values in a column in some table may mostly come from a sequence (or set of sequences), except for the values manually generated.
In other words, there is no mandatory connection between a column and a sequence - and therefore no way to discover such a relationship from the schema.
Ultimately, the analysis will be of the source code of all applications that insert or update data in the table. Nothing else is guaranteed. You can reduce the scope of the search if there is a stored procedure that is the only way to make modifications to the table, or if there is a trigger that sets the value, or other such things. But the general solution is the 'non-solution' of 'analyze the source'.
If the sequence is used in a trigger, it is possible to find which tables it populates:
SQL> select t.table_name, d.referenced_name as sequence_name
2 from user_triggers t
3 join user_dependencies d
4 on d.name = t.trigger_name
5 where d.referenced_type = 'SEQUENCE'
6 and d.type = 'TRIGGER'
7 /
TABLE_NAME SEQUENCE_NAME
------------------------------ ------------------------------
EMP EMPNO_SEQ
SQL>
You can vary this query to find stored procedures, etc that make use of the sequence.
There are no direct metadata links between Oracle sequences and any use in the database. You could make an intelligent guess if a column's values are related to a sequence by querying the USER_SEQUENCES metadata and comparing the LAST_NUMBER column to the data for the column.
select t.table_name,
d.referenced_name as sequence_name,
d.REFERENCED_OWNER as "OWNER",
c.COLUMN_NAME
from user_trigger_cols t, user_dependencies d, user_tab_cols c
where d.name = t.trigger_name
and t.TABLE_NAME = c.TABLE_NAME
and t.COLUMN_NAME = c.COLUMN_NAME
and d.referenced_type = 'SEQUENCE'
and d.type = 'TRIGGER'
As Jonathan pointed out: there is no direct way to relate both objects. However, if you "keep a standard" for primary keys and sequences/triggers you could find out by finding the primary key and then associate the constraint to the table sequence.
I was in need of something similar since we are building a multi-db product and I tried to replicate some classes with properties found in a DataTable object from .Net which has AutoIncrement, IncrementSeed and IncrementStep which can only be found in the sequences.
So, as I said, if you, for your tables, use a PK and always have a sequence associated with a trigger for inserts on a table then this may come handy:
select tc.table_name,
case tc.nullable
when 'Y' then 1
else 0
end as is_nullable,
case ac.constraint_type
when 'P' then 1
else 0
end as is_identity,
ac.constraint_type,
seq.increment_by as auto_increment_seed,
seq.min_value as auto_increment_step,
com.comments as caption,
tc.column_name,
tc.data_type,
tc.data_default as default_value,
tc.data_length as max_length,
tc.column_id,
tc.data_precision as precision,
tc.data_scale as scale
from SYS.all_tab_columns tc
left outer join SYS.all_col_comments com
on (tc.column_name = com.column_name and tc.table_name = com.table_name)
LEFT OUTER JOIN SYS.ALL_CONS_COLUMNS CC
on (tc.table_name = cc.table_name and tc.column_name = cc.column_name and tc.owner = cc.owner)
LEFT OUTER JOIN SYS.ALL_CONSTRAINTS AC
ON (ac.constraint_name = cc.constraint_name and ac.owner = cc.owner)
LEFT outer join user_triggers trg
on (ac.table_name = trg.table_name and ac.owner = trg.table_owner)
LEFT outer join user_dependencies dep
on (trg.trigger_name = dep.name and dep.referenced_type='SEQUENCE' and dep.type='TRIGGER')
LEFT outer join user_sequences seq
on (seq.sequence_name = dep.referenced_name)
where tc.table_name = 'TABLE_NAME'
and tc.owner = 'SCHEMA_NAME'
AND AC.CONSTRAINT_TYPE = 'P'
union all
select tc.table_name,
case tc.nullable
when 'Y' then 1
else 0
end as is_nullable,
case ac.constraint_type
when 'P' then 1
else 0
end as is_identity,
ac.constraint_type,
seq.increment_by as auto_increment_seed,
seq.min_value as auto_increment_step,
com.comments as caption,
tc.column_name,
tc.data_type,
tc.data_default as default_value,
tc.data_length as max_length,
tc.column_id,
tc.data_precision as precision,
tc.data_scale as scale
from SYS.all_tab_columns tc
left outer join SYS.all_col_comments com
on (tc.column_name = com.column_name and tc.table_name = com.table_name)
LEFT OUTER JOIN SYS.ALL_CONS_COLUMNS CC
on (tc.table_name = cc.table_name and tc.column_name = cc.column_name and tc.owner = cc.owner)
LEFT OUTER JOIN SYS.ALL_CONSTRAINTS AC
ON (ac.constraint_name = cc.constraint_name and ac.owner = cc.owner)
LEFT outer join user_triggers trg
on (ac.table_name = trg.table_name and ac.owner = trg.table_owner)
LEFT outer join user_dependencies dep
on (trg.trigger_name = dep.name and dep.referenced_type='SEQUENCE' and dep.type='TRIGGER')
LEFT outer join user_sequences seq
on (seq.sequence_name = dep.referenced_name)
where tc.table_name = 'TABLE_NAME'
and tc.owner = 'SCHEMA_NAME'
AND AC.CONSTRAINT_TYPE is null;
That would give you the list of columns for a schema/table with:
Table name
If column is nullable
Constraint type (only for PK's)
Increment seed (from the sequence)
Increment step (from the sequence)
Column comments
Column name, of course :)
Data type
Default value, if any
Length of column
Index (column id)
Precision (for numbers)
Scale (for numbers)
I'm pretty sure that code can be optimized but it works for me, I use it to "load metadata" for tables and then represent that metadata as entities on my frontend.
Note that I'm filtering only primary keys and not retrieving compound key constraints since I don't care about those. If you do you'll have to modify the code to do so and make sure that you filter duplicates since you could get one column twice (one for the PK constraint, another for the compound key).