I wanted to query to the hugeblob attribute in a table. I have tried below, but it doesnt give any data while selecting.
select DBMS_LOB.substr(mydata, 1000,1) from mytable;
Is there any other to do this?
DBMS_LOB.substr() is the right function to use. Ensure that there is data in the column.
Example usage:
-- create table
CREATE TABLE myTable (
id INTEGER PRIMARY KEY,
blob_column BLOB
);
-- insert couple of rows
insert into myTable values(1,utl_raw.cast_to_raw('a long data item here'));
insert into myTable values(2,null);
-- select rows
select id, blob_column from myTable;
ID BLOB_COLUMN
1 (BLOB)
2 null
-- select rows
select id, DBMS_LOB.substr(blob_column, 1000,1) from myTable;
ID DBMS_LOB.SUBSTR(BLOB_COLUMN,1000,1)
1 61206C6F6E672064617461206974656D2068657265
2 null
-- select rows
select id, UTL_RAW.CAST_TO_VARCHAR2(DBMS_LOB.substr(blob_column,1000,1)) from myTable;
ID UTL_RAW.CAST_TO_VARCHAR2(DBMS_LOB.SUBSTR(BLOB_COLUMN,1000,1))
1 a long data item here
2 null
Related
I think this requirement is rarely encountered so I couldn't search for similar questions.
I have a table that needs to update the ID. For example ID 123 in table1 is actually supposed to be 456. I have a separate reference table built that stores the mapping (e.g. old 123 maps to new id 456).
I used the below query but apparently it returned error 38104, columns referenced in the ON clause cannot be updated.
MERGE INTO table1
USING ref_table ON (table1.ID = ref_table.ID_Old)
WHEN MATCHED THEN UPDATE SET table.ID = ref_table.ID_New;
Is there other way to achieve my purpose?
Thanks and much appreciated for your answer!
Use the ROWID pseudocolumn:
SQL Fiddle
Oracle 11g R2 Schema Setup:
CREATE TABLE TABLE1( ID ) AS
SELECT 1 FROM DUAL UNION ALL
SELECT 2 FROM DUAL UNION ALL
SELECT 3 FROM DUAL;
CREATE TABLE REF_TABLE( ID_OLD, ID_NEW ) AS
SELECT 1, 4 FROM DUAL UNION ALL
SELECT 2, 5 FROM DUAL;
MERGE INTO TABLE1 dst
USING ( SELECT t.ROWID AS rid,
r.id_new
FROM TABLE1 t
INNER JOIN REF_TABLE r
ON ( t.id = r.id_old ) ) src
ON ( dst.ROWID = src.RID )
WHEN MATCHED THEN
UPDATE SET id = src.id_new;
Query 1:
SELECT * FROM table1
Results:
| ID |
|----|
| 4 |
| 5 |
| 3 |
You can't update a column used in the ON clause in a MERGE. But if you don't need to make other changes that MERGE allows like WHEN NOT MATCHED or deleting, etc. you can just use a UPDATE to achieve this.
You mentioned this is an ID that needs an update. Here's an example using a scalar subquery. As it is an ID, this presumes UNIQUE ID_OLD values in REF_TABLE. I wasn't sure if Every row needs an update or only a sub-set, so set the update here to only update rows that have a value in REF_TABLE.
CREATE TABLE TABLE1(
ID NUMBER
);
CREATE TABLE REF_TABLE(
ID_OLD NUMBER,
ID_NEW NUMBER
);
INSERT INTO TABLE1 VALUES (1);
INSERT INTO TABLE1 VALUES (2);
INSERT INTO TABLE1 VALUES (100);
INSERT INTO REF_TABLE VALUES (1,10);
INSERT INTO REF_TABLE VALUES (2,20);
Initial State:
SELECT * FROM TABLE1;
ID
1
2
100
Then make the UPDATE
UPDATE TABLE1
SET TABLE1.ID = (SELECT REF_TABLE.ID_NEW
FROM REF_TABLE
WHERE REF_TABLE.ID_OLD = ID)
WHERE TABLE1.ID IN (SELECT REF_TABLE.ID_OLD
FROM REF_TABLE);
2 rows updated.
And check the change:
SELECT * FROM TABLE1;
ID
10
20
100
I am trying to get the row number of an inserted record so I can use it for a select statement. What I am trying to accomplish is insert a person into one table, get that row number and then select something from another table where the row numbers match. Here is what I got so far:
INSERT INTO TableA Values (‘Person’)
Select timeToken
From
(
Select
Row_Number() Over (Order By tokenOrder) As RowNum
, *
From TableB WHERE taken = false
) t2
Where RowNum = (Row Number of Inserted Item)
How do I get the row number of the inserted item, I want to compare ids as some records might have been deleted so they would not match.
TABLEA Data (primary key is id)
id name
3 John
12 Steve
TABLEB Data (primary key is id)
id timeToken tokenOrder taken
2 1:00am 1 false
3 2:00am 2 false
5 3:00am 3 true
6 4:00am 4 false
My expect result when I insert person, the select take would return 4:00am
I am doing this in a stored procedure.
It is an error to think that rows have numbers unless an ORDER BY clause is included.
The only way to find a row after you have inserted it is to search for it. Presumably your table has a primary key; use that to search for it.
Try This .It may help you out
Declare #TableA_PK BIGINT
INSERT INTO TableA Values ('Person')
SET #TableA_PK=SCOPE_IDENTITY()
Select timeToken
From
(
Select
Row_Number() Over (Order By tokenOrder) As RowNum
, *
From TableB WHERE taken = false
) t2
Where RowNum =#TableA_PK
SCOPE_IDENTITY(): Scope Identity will captures the last inserted record primary key value and which can be stored in a varaible and
and then it can be for further re-use
By the sounds of it you are trying to do something like what is listed on thhe following link LINK - SQL Server - Return value after INSERT
Basically :
INSERT INTO TableA (Person)
OUTPUT Inserted.ID
VALUES('bob');
Adding a foreign key constraint(referencing primary key in table A) in table b will be good since you won't be able to delete records from table A without deleting them from table B. It'll be helpful for comparing the records using ID.
Try this
declare #rowNum int;
INSERT INTO TableA Values ('Person')
SET #rowNum =SCOPE_IDENTITY()
select * from TableA where id = #rowNum
I am new to SQL and I an trying to understand the GROUP BY statement.
I have inserted the following data in SQL:
CREATE TABLE table( id integer, type text);
INSERT INTO table VALUES (1,'start');
INSERT INTO table VALUES (2,'start');
INSERT INTO table VALUES (2,'complete');
INSERT INTO table VALUES (3,'complete');
INSERT INTO table VALUES (3,'start');
INSERT INTO table VALUES (4,'start');
I want to select those IDs that do not have a type 'complete'. For this example I should get IDs 1, 4.
I have tried multiple GROUP BY - HAVING combinations. My best approach is:
SELECT id from customers group by type having type!='complete';
but the resulted IDs are 4,3,2.
Could anyone give me a hint about what I am doing wrong?
You are close. The having clause needs an aggregation function and you need to aggregate by id:
select id
from table t
group by id
having sum(case when type = 'complete' then 1 else 0 end) = 0;
Normally, if you have something called an id, you would also have a table with that as primary key. If so, you can also do:
select it.id
from idtable it
where not exists (select 1
from table t
where t.type = 'complete' and it.id = t.id
);
I'm unable to write a working LIKE query for a field containing the German sharp-s (ß) in a case-insensitive text field.
Using HSQLDB 2.2.9, create a table with a case sensitive field and a case insensitive field.
CREATE CACHED TABLE MYTABLE (MYKEY LONGVARCHAR NOT NULL, PRIMARY KEY (MYKEY));
ALTER TABLE MYTABLE ADD COLUMN SEN LONGVARCHAR;
ALTER TABLE MYTABLE ADD COLUMN INSEN VARCHAR_IGNORECASE;
Write 2 records.
INSERT INTO MYTABLE (MYKEY, SEN, INSEN) VALUES ('1', 'Strauß', 'Strauß');
INSERT INTO MYTABLE (MYKEY, SEN, INSEN) VALUES ('2', 'Strauss', 'Strauss');
Verify.
SELECT * FROM MYTABLE
KEY, SEN, INSEN
'1', 'Strauß', 'Strauß'
'2', 'Strauss', 'Strauss'
The problem query:
SELECT * FROM MYTABLE WHERE INSEN LIKE '%ß%'
WRONG, RETURNS RECORD 2 NOT RECORD 1
These queries work as expected:
SELECT * FROM MYTABLE WHERE SEN LIKE '%ß%'
OK, RETURNS RECORD 1
SELECT * FROM MYTABLE WHERE UCASE(INSEN) LIKE '%ß%'
OK, RETURNS RECORDS 1 AND 2
SELECT * FROM MYTABLE WHERE UCASE(SEN) LIKE '%ß%'
OK, RETURNS NOTHING
SELECT * FROM MYTABLE WHERE SEN='Strauß'
OK, RETURNS RECORD 1
SELECT * FROM MYTABLE WHERE INSEN='Strauß'
OK, RETURNS RECORD 1
SELECT * FROM MYTABLE WHERE SEN='Strauss'
OK, RETURNS RECORD 2
SELECT * FROM MYTABLE WHERE INSEN='Strauss'
OK, RETURNS RECORD 2
Thanks!
i got a problem once again :D
a little info first:
im trying to copy data from one table to an other table(structure is the same).
now one cell needs to be incremented, beginns per group at 1 (just like a histroy).
i have this table:
create table My_Test/My_Test2 (
my_Id Number(8,0),
my_Num Number(6,0),
my_Data Varchar2(100));
(my_Id, my_Num is a nested PK)
if i want to insert a new row, i need to check if the value in my_id already exists.
if this is true then i need to use the next my_Num for this Id.
i have this in my Table:
My_Id My_Num My_Data
1 1 'test1'
1 2 'test2'
2 1 'test3'
if i add now a row for my_Id 1, the row would look like this:
i have this in my Table:
My_Id My_Num My_Data
1 3 'test4'
this sounds pretty easy ,now i need to make it in a SQL
and on SQL Server i had the same problem and i used this:
Insert Into My_Test (My_Id,My_Num,My_Data)
SELECT my_Id,
(
SELECT
CASE (
CASE MAX(a.my_Num)
WHEN NULL
THEN 0
Else Max(A.My_Num)
END) + b.My_Num
WHEN NULL
THEN 1
ELSE (
CASE MAX(a.My_Num)
WHEN NULL
THEN 0
Else Max(A.My_Num)
END) + b.My_Num
END
From My_Test A
where my_id = 1
)
,My_Data
From My_Test2 B
where my_id = 1;
this Select gives null back if no Rows are found in the subselect
is there a way so i could use max in the case? and if it give null back it should use 0 or 1?
Edit:
Im usung now this:
Insert INTO My_Test ( My_Id,My_Num,My_Data )
SELECT B.My_Id,
(
SELECT COALESCE(MAX(a.My_Num),0) + b.my_Num
FROM My_Test A
Where a.My_Id = b.My_Id)
,b.My_Data
FROM My_Test2 B
WHERE My_Id = 1
THX to Bharat and OMG Ponies
greets
Auro
Try this one
Insert Into My_Test (My_Id,My_Num,My_Data)
SELECT my_Id,(
SELECT MAX(NVL(My_Num,0)) + 1
From My_Test
where my_id = b.my_id
)
,My_Data
From My_Test2 B
where my_id = <your id>;
Insert Into My_Test (My_Id,My_Num,My_Data)
select My_id,coalesce(max(My_num),0),'test4' from My_Test
where My_id=1
group by My_id
All solutions have a problem in that they don't work in a multi user environment. If two sessions issue that insert statement at the same time, they would both get the same (my_id,my_num) combination, and one of them will fail with a ORA-00001 unique constraint violation. Therefore, if you need this to work in a multi user environment, the best advice is to use only one primary key column and populate it with a sequence. Keep your my_id column as well, as that is a sort-of-grouping column or foreign key column. If your end users really like to see the "my_num" column in their (web) application, you can use the row_number analytic function.
You can read more about this scenario in this blogpost of mine: http://rwijk.blogspot.com/2008/01/sequence-within-parent.html
Regards,
Rob.