I want to modify my SELECT statement as follows
SELECT blob_data from table where id = ?
TO
SELECT blob_data from table where id IN (?, ?, ?, ?, ?)
TABLE
ID NOT NULL VARCHAR2(255)
BLOB_DATA BLOB
The problem with this approach is that when executing the loop in Java, I may have less than 5 IDs. I want to write a stored procedure+CallableStatement instead of a PreparedStatement to fire the second query. [I thought of writing 5 different stored procedures which accept 1 to 5 arguments, but I think there should be a better approach!]
How can I write a stored procedure which accepts a variable number of bind parameters? Also, how will the Java and corresponding Oracle code look?
I will be very grateful for help with this code
Use collections instead, for example:
SELECT blob_data from table where id IN (select * from table(?))
So you will need just to bind collection.
Create your own collection type and use it in your queries, for example:
create type number_table as table of number;
Just for testing purpose (not production) you can use internal sys.ku$_objnumset (table of number) or sys.odcinumberlist(varray of number)
Related
Thank you for reply guys. I kind of solved my problem.
I used to try to update data with ref cursor in dynamic SQL using "where current of" but I now know that won't work.
Then I tried to use %rowtype to store both 'id' and 'clob' in one variable for future updating but turns out weak ref cursor can't use that type binding either.
After that I tried to use record as return of an ref cursor and that doesn't work on weak cursor either.
On the end, I created another cursor to retrieve 'id' separately along with cursor to retrieve 'clob' on the same time then update table with that id.
I'm now working on a Oracle data cleaning task and have a requirement like below:
There are 38 tables(maybe more in the future) and every table has one or multiple column which type is Clob. I need to find different keyword in those columns and according to a logic return binary label of the column and store it in a new column.
For example, there is a table 'myTable1' which has 2 Clob columns 'clob1' and 'clob2'. I'd like to find keyword 'sky' from those columns and store '0'(if not found) or '1'(if found) in two new columns 'clob1Sky','clob2Sky'.
I know if I could write it on a static way which will provide higher efficiency but I have to modify it for those very similar tasks every time. I want save some time on this so I'm trying to write it in a reusable way and not binding to certain table.
But I met some problem when writing the program. My program is like below:
create or replace PACKAGE body LABELTARGETKEYWORD
as
/**
#param varcher tableName: the name of table I want to work on
#param varchar colName: the name of clob column
#param varchar targetWord: the word I want to find in the column
#param varchar newColName: the name of new column which store label of clob
*/
PROCEDURE mainProc(tableName varchar, colName varchar,targetWord varchar,newColName varchar2)
as
type c_RecordCur is ref cursor;
c_sRecordCur c_recordCur;
/*other variables*/
begin
/*(1) check whether column of newColName exist
(2) if not, alter add table of newColName
(3) open cursor for retrieving clob
(4) loop cursor
(5) update set the value in newColName accroding to func labelword return
(6) close cursor and commit*/
end mainProc;
function labelWord(sRecord VARCHAR2,targetWord varchar2) return boolean...
function ifColExist(tableName varchar2,newColName varchar2) return boolean...
END LABELTARGETKEYWORD;
Most DML and DDL are written in dynamic sql way.
The problem is when I write the (5) part, I notice 'Where current of' clause can not be used in a ref cursor or dynamic sql statement. So I have to change the plan.
I tried to use a record(rowid,label) to store result and alter the table later.(the table only be used by two people in my group, so there won't be problem of lock and data changes). But I find because I'm trying to use dynamic sql so actually I have to define ref cursor with return of certain %rowtype and basically all other variables, %type in dynamic sql statement. Which makes me feel my method has something wrong.
My question are:
If there a way to define %type in dynamic sql? Binding type to variable in dynamic SQL?
Could anybody give me a hint how to write that (5) part in dynamic SQL?
Should not I design my program like that?
Is it not the way how to use dynamic SQL or PLSQL?
I'm very new to PL/SQL. Thank you very much.
According to Tom Kyte's advice, to do it in one statement if it can be done in one statement, I'd try to use a single UPDATE statement first:
CREATE TABLE mytable1 (id NUMBER, clob1 CLOB,
clob2 CLOB, clob1sky NUMBER, clob2sky NUMBER )
LOB(clob1, clob2) STORE AS SECUREFILE (ENABLE STORAGE IN ROW);
INSERT INTO mytable1(id, clob1, clob2)
SELECT object_id, object_name, object_type FROM all_objects
WHERE rownum <= 10000;
CREATE OR REPLACE
PROCEDURE mainProc(tableName VARCHAR2, colName VARCHAR2, targetWord VARCHAR2, newColName VARCHAR2)
IS
stmt VARCHAR2(30000);
BEGIN
stmt := 'UPDATE '||tableName||' SET '||newColName||'=1 '||
'WHERE DBMS_LOB.INSTR('||colName||','''||targetWord||''')>1';
dbms_output.put_line(stmt);
EXECUTE IMMEDIATE stmt;
END mainProc;
/
So, calling it with mainProc('MYTABLE1', 'CLOB1', 'TAB', 'CLOB1SKY'); fires the statement
UPDATE MYTABLE1 SET CLOB1SKY=1 WHERE DBMS_LOB.INSTR(CLOB1,'TAB')>1
which seems to do the trick:
SELECT * FROM mytable1 WHERE clob1sky=1;
id clob1 clob2 clob1sky clob2skiy
33 I_TAB1 INDEX 1
88 NTAB$ TABLE 1
89 I_NTAB1 INDEX 1
90 I_NTAB2 INDEX 1
...
I am not sure with your question-
If this job is suppose to run on daily or hourly basis ,running query through it will be very costly. One thing you can do - put all your clob data in a file and save it in your server(i guess it must be linux). then you can create a shell script and schedule a job to run gerp command and fetch your required value and "if found then update your table".
I think you should approaches problem another way:
1. Find all columns that you need:
CURSOR k_clobs
select table_name, column_name from dba_tab_cols where data_type in ('CLOB','NCLOB');
Or 2 cursor(you can build you query if you have more than 1 CLOB per table:
CURSOR k_clobs_table
select DISTINCT table_name from dba_tab_cols where data_type in ('CLOB','NCLOB');
CURSOR k_clobs_columns(table_namee varchar(255)) is
select column_name from dba_tab_cols where data_type in ('CLOB','NCLOB') and table_name = table_namee;
Now you are 100% that column you are checking is clob, so you don't have to worry about data type ;)
I'm not sure what you want achieve, but i hope it may help you.
The following statement is used on db2 to perform an UPSERT operation:
MERGE INTO mytable AS mt USING (
SELECT * FROM TABLE (
VALUES
(?, ?),
(?, ?),
—- ^ repeated many times, one for each row to be upserted
)
) AS vt(id, val) ON (mt.id = vt.id)
WHEN MATCHED THEN
UPDATE SET val = vt.val
WHEN NOT MATCHED THEN
INSERT (id, val) VALUES (vt.id, vt.val)
;
Every time I call this statement, I will have a different number of rows to be inserted. Is it possible to make this call using a prepared statement? What would that look like?
Ref: https://stackoverflow.com/a/23784606/1033422
If the number of ? parameter-markers varies per run then you must re-prepare if the number of parameter-markers changes. I would use a Declared Global Temporary Table (DGTT) especially if there are very large numbers of rows. Yes, more statements, but easier to scale because you can dynamically index the DGTT.
For more information on temporary tables in DB2, see this question.
I have function which returns column names and i am trying to use the column name as part of my select statement, but my results are coming as column name instead of values
FUNCTION returning column name:
get_col_name(input1, input2)
Can И use this query to the results of the column from table -
SELECT GET_COL_NAME(input1,input2) FROM TABLE;
There are a few ways to run dynamic SQL directly inside a SQL statement. These techniques should be avoided since they are usually complicated, slow, and buggy. Before you do this try to find another way to solve the problem.
The below solution uses DBMS_XMLGEN.GETXML to produce XML from a dynamically created SQL statement, and then uses XML table processing to extract the value.
This is the simplest way to run dynamic SQL in SQL, and it only requires built-in packages. The main limitation is that the number and type of columns is still fixed. If you need a function that returns an unknown number of columns you'll need something more powerful, like the open source program Method4. But that level of dynamic code gets even more difficult and should only be used after careful consideration.
Sample schema
--drop table table1;
create table table1(a number, b number);
insert into table1 values(1, 2);
commit;
Function that returns column name
create or replace function get_col_name(input1 number, input2 number) return varchar2 is
begin
if input1 = 0 then
return 'a';
else
return 'b';
end if;
end;
/
Sample query and result
select dynamic_column
from
(
select xmltype(dbms_xmlgen.getxml('
select '||get_col_name(0,0)||' dynamic_column from table1'
)) xml_results
from dual
)
cross join
xmltable
(
'/ROWSET/ROW'
passing xml_results
columns dynamic_column varchar2(4000) path 'DYNAMIC_COLUMN'
);
DYNAMIC_COLUMN
--------------
1
If you change the inputs to the function the new value is 2 from column B. Use this SQL Fiddle to test the code.
I'm executing a master stored procedure to load columns in to a target table.
I have a column called dptname - this column is handled by different project team so they have defined a child stored procedure all that will do is it will get an empno and output the Dptname. They requested us to call the below stored procedure to load my dptname column.
Could you please let me know how can I assign/call this child stored procedure and assign to the deptname column in my master stored procedure?
This is the skeleton of the child stored procedure:
get_dptname(in_emp_no, out_dptname)
My master stored procedure:
Create or Replace procedure InsertTargetTable
as
begin
for a in (
Select EMP.empno
EMP.NAME,
CL.Attendance,
DEPTNAME= "**ASSIGN THE VALUE FROM THE 3rd Party stored procedure**
from EMP, CL
on EMP.empno=CL.empno
) Loop
Insert Into Target Table ( empno, NAME,Attendance, DEPTNAME )
Values (a.empno, a.NAME, a.Attendance, a.DEPTNAME);
ENDLOOP;
COMMIT:
END
If the other group created a function GET_DEPT_NAME, then you could use it as follows:
CREATE OR REPLACE PROCEDURE InsertTargetTable
AS
BEGIN
INSERT INTO Target_Table ( empno, NAME, Attendance, DEPTNAME )
SELECT EMP.empno, EMP.NAME, CL.Attendance, GET_DEPT_NAME(EMP.empno)
FROM EMP, CL
WHERE EMP.empno = CL.empno;
COMMIT:
END;
A few notes:
The data is being de-normalizing: what if the employee changes departments? Your Target_Table won't be updated but will remain fixed at the department set during insert. Perhaps the department should be looked up when the table is actually queried in order to obtain the current department value.
Hopefully the stored proc is a function, then it can be used easily as shown in the example above. (If not, ask for a function).
Avoid looping if possible. A single "insert into ... select from" statement will be much more efficient.
You can use following query. Pass the DEPT_NO variable to stored procedure and since it is an OUT parameter you can access value from your master stored procedure.
GET_DPTNAME(IN_EMP_NO=>EMP_NO,OUT_DEPT_NO=>DEPT_NO);
I have a simple table with one column of numbers. I want to load about 3000 numbers in it. I want to do that in memory, without using SQL*Loader. I tried
INSERT ALL
INTO t_table (code) VALUES (n1)
INTO t_table (code) VALUES (n2)
...
...
INTO t_table (code) VALUES (n3000)
SELECT * FROM dual
But I fails at 1000 values. What should I do ? Is SQL*Loader the only way ? Can I do LOAD with SQL only ?
Presumably you have an initial value of n. If so, this code will populate code with values n to n+2999 :
insert into t_table (code)
select (&N + level ) - 1
from dual
connect by level <=3000
This query uses a SQL*Plus substitution variable to post the initial value of n. Other clients will need to pass the value in a different way.
"Assume that I am in c++ with a stl::vector, what query should I
write ?"
So when you wrote n3000 what you really meant was n(3000). It's easy enough to use an array in SQL. This example uses one of Oracle's pre-defined collections, a table of type NUMBER:
declare
ids system.number_tbl_type;
begin
insert into t_table (code)
select column_value
from table ( select ids from dual )
;
end;
As for mapping your C++ vector to Oracle types, that's a different question (and one which I can't answer).