We are trying to modify the precision on existing columns in the database. Those which have been defined as NUMBER, we want to change it to NUMBER(14,2).
But, since NUMBER has a default precision of 38, there exist values in the database which run into more than 10 decimal places. So, when we create an additional column and try to copy over from a temp table, this results in errors.
select count(*) into countCol from USER_TAB_COLUMNS where TABLE_NAME = 'EVAPP_INTERFACE' and COLUMN_NAME = 'RESERVE_RATE_NUM' and DATA_SCALE is null;
IF (countCol <> 0) then
execute immediate 'alter table EVAPP_INTERFACE add RESERVE_RATE_NUM_TMP NUMBER(6,3)' ;
execute immediate 'update EVAPP_INTERFACE set RESERVE_RATE_NUM_TMP = RESERVE_RATE_NUM' ;
execute immediate 'alter table EVAPP_INTERFACE drop column RESERVE_RATE_NUM' ;
execute immediate 'alter table EVAPP_INTERFACE rename column RESERVE_RATE_NUM_TMP to RESERVE_RATE_NUM' ;
DBMS_OUTPUT.put_line('This column EVAPP_INTERFACE.RESERVE_RATE_NUM has been modified to the required precision');
Is there any way to truncate all values in a column?
Like say a column has
43.8052201822
21.1610909091
76.4761223618
75.8535613657
I want them all changed to
43.8
21.16
76.47
75.85
EDIT : I know the word Truncate is used wrongly, but I don't know of a better term to shaving off precision.
Not a wrong word at all, see: TRUNC(number).
From the example below you can see the difference of truncating and rounding:
create table foo(n number);
insert all
into foo values (1.111)
into foo values (5.555)
into foo values (9.999)
select * from dual;
select n, round(n,2), trunc(n, 2) from foo;
N ROUND(N,2) TRUNC(N,2)
---------- ---------- ----------
1.111 1.11 1.11
5.555 5.56 5.55
9.999 10 9.99
How about using ROUND (number)?
Related
Suppose if the table name is ABC_XYZ_123. I want to extract the integer values after _.
The output should be integer values after _.
In the above case, the output should be 123.
I have used the below sql query.
select from table_name like 'XXX_%';
But I am not getting required output. Can anyone help me with this query.
Thanks
Using REGEXP_SUBSTR with a capture group we can try:
SELECT REGEXP_SUBSTR(name, '_(\d+)$', 1, 1, NULL, 1)
FROM yourTable;
The question is somewhat unclear:
it looks as if you're looking for table names that contain number at the end, while
query you posted suggests that you're trying to select those numbers from one of table's columns
I'll stick to
Suppose if the table name is ABC_XYZ_123
If that's so, it is the data dictionary you'll query. USER_TABLES contains that information.
Let's create that table:
SQL> create table abc_xyz_123 (id number);
Table created.
Query selects numbers at the end of table names, for all my tables that end with numbers.
SQL> select table_name,
2 regexp_substr(table_name, '\d+$') result
3 from user_tables
4 where regexp_like(table_name, '\d+$');
TABLE_NAME RESULT
-------------------- ----------
TABLE1 1
TABLE2 2
restore_point-001 001
ABC_XYZ_123 123 --> here's your table
SQL>
Apparently, I have a few of them.
Oracle - Alter all table column names with trim of white space in between names
For suppose column names before alter :
Home number
Mobile number
Local number
After alter column names shall be :
Homenumber
Mobilenumber
Localnumber
I've tried this way: but unable to crack:
UPDATE SA_VW_PHONENUMBER TN SET TN.Column_Name = TRIM (TN.Column_Name);
Fully automatic way
Use this cursor based DDL hacking - statement concat.
BEGIN
FOR alters IN
(
SELECT
'ALTER TABLE "'||table_name||'" RENAME COLUMN "'||column_name||
'" TO "'||replace(cols.column_name,' ','')||'"' sql_stmt
FROM all_tab_cols cols
WHERE REGEXP_LIKE(column_name,'[[:space:]]')
AND owner = user --Add real schema name here
ORDER BY 1
) LOOP
DBMS_OUTPUT.PUT_LINE ( alters.sql_stmt ||';') ;
EXECUTE IMMEDIATE alters.sql_stmt;
END LOOP;
END;
/
If you want to use the safe way
As I know you cannot perform a DDL as a dynamic SQL, so you cannot pass variables to the ALTER TABLE command, but here is what you can do instead of that.
Selecting the occurences:
SELECT table_name,column_name,replace(cols.column_name,' ','') as replace_name
FROM all_tab_cols
WHERE REGEXP_LIKE(column_name,'[[:space:]]');
Use the ALTER TABLE DDL command:
alter table T_TABLE rename column "COLUMN SPACE" TO "COLUMNNOSPACE";
Try the REPLACE function
UPDATE SA_VW_PHONENUMBER TN SET TN.Column_Name = REPLACE(TN.Column_Name,' ','')
I'm trying to use a nested table inside the IN clause in a PL-SQL block.
First, I have defined a TYPE:
CREATE OR REPLACE TYPE VARCHAR_ARRAY AS TABLE OF VARCHAR2(32767);
Here is my PL-SQL block using the 'BULK COLLECT INTO':
DECLARE
COL1 VARCHAR2(50) := '123456789';
N_TBL VARCHAR_ARRAY := VARCHAR_ARRAY();
C NUMBER;
BEGIN
-- Print timestamp
DBMS_OUTPUT.PUT_LINE('START: ' || TO_CHAR(SYSTIMESTAMP ,'dd-mm-yyyy hh24:mi:ss.FF'));
SELECT COLUMN1
BULK COLLECT INTO N_TBL
FROM MY_TABLE
WHERE COLUMN1 = COL1;
SELECT COUNT(COLUMN1)
INTO C
FROM MY_OTHER_TABLE
WHERE COLUMN1 IN (SELECT column_value FROM TABLE(N_TBL));
-- Print timestamp
DBMS_OUTPUT.PUT_LINE('ENDED: ' || TO_CHAR(SYSTIMESTAMP ,'dd-mm-yyyy hh24:mi:ss.FF'));
END;
And the output is:
START: 01-08-2014 12:36:14.997
ENDED: 01-08-2014 12:36:17.554
It takes more than 2.5 seconds (2.557 seconds exactly)
Now, If I replace the nested table by a subquery, like this:
DECLARE
COL1 VARCHAR2(50) := '123456789';
N_TBL VARCHAR_ARRAY := VARCHAR_ARRAY();
C NUMBER;
BEGIN
-- Print timestamp
DBMS_OUTPUT.PUT_LINE('START: ' || TO_CHAR(SYSTIMESTAMP ,'dd-mm-yyyy hh24:mi:ss.FF'));
SELECT COUNT(COLUMN1)
INTO C
FROM MY_OTHER_TABLE
WHERE COLUMN1 IN (
-- Nested table replaced by a subquery
SELECT COLUMN1
FROM MY_TABLE
WHERE COLUMN1 = COL1
);
-- Print timestamp
DBMS_OUTPUT.PUT_LINE('ENDED: ' || TO_CHAR(SYSTIMESTAMP ,'dd-mm-yyyy hh24:mi:ss.FF'));
END;
The output is:
START: 01-08-2014 12:36:08.889
ENDED: 01-08-2014 12:36:08.903
It takes only 14 milliseconds...!!!
What could I do to enhance this PL-SQL block ?
Is there any database configuration needed?
Are the two query plans different?
Assuming that they are, the difference is likely that the optimizer has reasonable estimates about the number of rows the subquery will return and, thus, is able to choose the most efficient plan. When your data is in a nested table (I'd hate to use the word array in the type declaration here since that implies that you're using a varray when you're not), Oracle doesn't have information about how many elements are going to be in the collection. By default, it's going to guess that the collection has as many elements as your data blocks have bytes. So if you have 8k blocks, Oracle will guess that your collection has 8192 elements.
Assuming that your actual query doesn't return anywhere close to 8192 rows and that it actually returns many more or many fewer rows, you can potentially use the cardinality hint to let the optimizer make a more accurate guess. For example, if your query generally returns a few dozen rows, you probably want something like
SELECT COUNT(COLUMN1)
INTO C
FROM MY_OTHER_TABLE
WHERE COLUMN1 IN (SELECT /*+ cardinality(t 50) */ column_value
FROM TABLE(N_TBL) t);
The literal you put in the cardinality hint doesn't need to be particularly accurate, just close to general reality. If the number of rows is completely unknown the dynamic_sampling hint can help.
If you are using Oracle 11g, you may also benefit from cardinality feedback helping the optimizer learn to better estimate the number of elements in a collection.
Do want to create Stored procc which updates or inserts into table based on the condition if current line does not exist in table?
This is what I have come up with so far:
PROCEDURE SP_UPDATE_EMPLOYEE
(
SSN VARCHAR2,
NAME VARCHAR2
)
AS
BEGIN
IF EXISTS(SELECT * FROM tblEMPLOYEE a where a.ssn = SSN)
--what ? just carry on to else
ELSE
INSERT INTO pb_mifid (ssn, NAME)
VALUES (SSN, NAME);
END;
Is this the way to achieve this?
This is quite a common pattern. Depending on what version of Oracle you are running, you could use the merge statement (I am not sure what version it appeared in).
create table test_merge (id integer, c2 varchar2(255));
create unique index test_merge_idx1 on test_merge(id);
merge into test_merge t
using (select 1 id, 'foobar' c2 from dual) s
on (t.id = s.id)
when matched then update set c2 = s.c2
when not matched then insert (id, c2)
values (s.id, s.c2);
Merge is intended to merge data from a source table, but you can fake it for individual rows by selecting the data from dual.
If you cannot use merge, then optimize for the most common case. Will the proc usually not find a record and need to insert it, or will it usually need to update an existing record?
If inserting will be most common, code such as the following is probably best:
begin
insert into t (columns)
values ()
exception
when dup_val_on_index then
update t set cols = values
end;
If update is the most common, then turn the procedure around:
begin
update t set cols = values;
if sql%rowcount = 0 then
-- nothing was updated, so the record doesn't exist, insert it.
insert into t (columns)
values ();
end if;
end;
You should not issue a select to check for the row and make the decision based on the result - that means you will always need to run two SQL statements, when you can get away with one most of the time (or always if you use merge). The less SQL statements you use, the better your code will perform.
BEGIN
INSERT INTO pb_mifid (ssn, NAME)
select SSN, NAME from dual
where not exists(SELECT * FROM tblEMPLOYEE a where a.ssn = SSN);
END;
UPDATE:
Attention, you should name your parameter p_ssn(distinguish to the column SSN ), and the query become:
INSERT INTO pb_mifid (ssn, NAME)
select P_SSN, NAME from dual
where not exists(SELECT * FROM tblEMPLOYEE a where a.ssn = P_SSN);
because this allways exists:
SELECT * FROM tblEMPLOYEE a where a.ssn = SSN
I would like to do an INSERT / SELECT, this means INSERT in the TARGET_TABLE the records of the SOURCE_TABLE, with this assumption:
The SOURCE and the TARGET table have only a SUBSET of common columns, this means in example:
==> The SOURCE TABLE has ALPHA, BETA and GAMMA columns;
==> The TARGET TABLE has BETA, GAMMA and DELTA columns.
What is the most efficient way to produce INSERT / SELECT statements, respecting the assumption that not all the target columns are present in the source table?
The idea is that the PL/SQL script CHECKS the columns in the source table and in the target table, makes the INTERSECTION, and then produces a dynamic SQL with the correct list of columns.
Please assume that the columns present in the target table, but not present in the source table, have to be left NULL.
I wish to extract the data from SOURCE into a set of INSERT statements for later insertion into the TARGET table.
You can assume that the TARGET table has more columns than the SOURCE table, and that all the columns in the SOURCE table are present in the TARGET table in the same order.
Thank you in advance for your useful suggestions!
In Oracle, You can get common columns with this SQL query:
select column_name
from user_tab_columns
where table_name = 'TABLE_1'
intersect
select column_name
from user_tab_columns
where table_name = 'TABLE_2'
Then you iterate a cursor with the mentioned query to generate a comma separated list of all values returned. Put that comma separated string into a varchar2 variable named common_fields. Then, you can:
sql_sentence := 'insert into TABLE_1 (' ||
common_fields ||
') select ' ||
common_fields ||
' from TABLE_2';
execute immediate sql_sentence;