I have a column, say PROD_NUM that contains a 'number' that is left padded with zeros. For example 001004569. They are all nine characters long.
I do not use a numeric type because the normal operation on numbers do not make sense on these "numbers" (For example PROD_NUM * 2 does not make any sense.) And since they are all the same length, the column is defined as a CHAR(9)
CREATE TABLE PRODUCT (
PROD_NUM CHAR(9) NOT NULL
-- ETC.
)
I would like to constrain PROD_NUM so it can only contain nine digits. No spaces, no other characters besides '0' through '9'
REGEXP_LIKE(PROD_NUM, '^[[:digit:]]{9}$')
You already received some nice answers on how to continue on your current path. Please allow me to suggest a different path: use a number(9,0) datatype instead.
Reasons:
You don't need an additional check constraint to confirm it contains a real number.
You are not fooling the optimizer. For example, how many prod_num's are "BETWEEN '000000009' and '000000010'"? Lots of character strings fit in there. Whereas "prod_num between 9 and 10" obviously selects only two numbers. Cardinalities will be better, leading to better execution plans.
You are not fooling future colleagues who have to maintain your code. Naming it "prod_num" will have them automatically assume it contains a number.
Your application can use lpad(to_char(prod_num),9,'0'), preferably exposed in a view.
Regards,
Rob.
(update by MH) The comment thread has a discussion which nicely illustrates the various things to consider about this approach. If this topic is interesting you should read them.
Works in all versions:
TRANSLATE(PROD_NUM,'123456789','000000000') = '000000000'
I think Codebender's regexp will work fine but I suspect it is a bit slow.
You can do (untested)
replace(translate(prod_num,'0123456789','NNNNNNNNNN'),'N',null) is null
Cast it to integer, cast it back to varchar, and check that it equals the original string?
In MSSQL, I might use something like this as the constraint test:
PROD_NUM NOT LIKE '%[^0-9]%'
I'm not an Oracle person, but I don't think they support bracketed character lists.
in MS SQL server I use this command:
alter table add constraint [cc_mytable_myfield] check (cast(myfield as bigint) > 0)
Not sure about performance but if you know the range, the following will work.
Uses a CHECK constraint at the time of creating the DDL.
alter table test add jz2 varchar2(4)
check ( jz2 between 1 and 2000000 );
as will
alter table test add jz2 varchar2(4)
check ( jz2 in (1,2,3) );
this will also work
alter table test add jz2 varchar2(4)
check ( jz2 > 0 );
Related
How to change column type from varchar2(10) to char(10) without losing existing data using oracle developer?
ALTER TABLE TBL_NAME
MODIFY (CRTE CHAR(10));
Will it impact existing data?
It should not impact existing data.
See this SQL Fiddle.
I would reconsider changing varchar2 for char. Char will take up more space on HDD as char will always take N bytes. And if your strings are not execatly 10 characters, all of them char will be pain for searches.
There is really no reason to do this. As this "Ask Tom" answer, explains, the two are stored equivalently.
If you want to ensure that the value has exactly 10 characters, then use a check constraint:
ALTER TABLE TBL_NAME ADD CONSTRAINT CHECK (LEN(CRTE) = 10);
The difference is padding the string in result sets, and that is often better handled on an ad-hoc basis. Trailing spaces can be quite tricky to deal with.
If you really want to change the column type, you can use:
alter table t modify ( x char(10) );
This should be safe with existing data, because you are not reducing the length of the column.
I have to make oracle constraints that checks if username is minimum 3 and maximum 10 lowercase letters.
I have used
constraint usernameSMALLCASE check (
REGEXP_Like(username,'^[a-z]{10}$') or
REGEXP_Like(username,'^[a-z]{9}$') or
REGEXP_Like(username,'^[a-z]{8}$') or
REGEXP_Like(username,'^[a-z]{7}$') or
REGEXP_Like(username,'^[a-z]{6}$') or
REGEXP_Like(username,'^[a-z]{5}$') or
REGEXP_Like(username,'^[a-z]{4}$') or
REGEXP_Like(username,'^[a-z]{3}$')
)
However, it is not working.
Somehow, putting $ is causing problem. But I have to put $ to make sure end of the end of line char is also small case.
Your code should work if your column is declared correctly. But you can drastically simplify it:
constraint usernameSMALLCASE check ( REGEXP_Like(username, '^[a-z]{3,10}$') )
Obviously there are other methods besides regular expressions for handling this. However, you have started down the regular expression route and it is simple enough using one.
If you insist on a fixed length column, you can express this as:
constraint usernameSMALLCASE check ( REGEXP_Like(username, '^[a-z]{3,10} *$') )
Create constraint for
username = lower(username) and length(username) > 3
The max length you can enforce by data type
username VARCHAR2(10 CHAR) NOT NULL
Note, regular expression ^[a-z]{3,10}$ is not fully reliable, see Character Class '[: :]' in Regular Expressions
A non-working example is this one:
ALTER SESSION SET NLS_SORT = XSPANISH;
BEGIN
IF REGEXP_LIKE('ch', '^[a-d]$') THEN
DBMS_OUTPUT.PUT_LINE('TRUE');
ELSE
DBMS_OUTPUT.PUT_LINE('FALSE');
END _IF;
END;
Returns TRUE (despite h is not between a-d) because ch in traditional Spanish is considered as one sorting character.
I think a 100% reliable constraint would be like this:
REGEXP_LIKE(TRANSLATE(username, 'abcdefghijklmnopqrstuvwxyz', '**************************'), '^\*{3,10}$')
AND username NOT LIKE '%*%'
I am currently creating a database project wherein it only accepts a valid phone number that starts with "09" then the rest are any numbers, although it should be limited to only 11 numbers including 09. With my code below, it accepnt only 11 numbers but even when I tried numbers 63256115426 like that it can still be accepted.
([ContactNo]>=(0) AND [ContactNo]<=(9999999999.))
The first issue you've out there is that you're using the wrong datatype for phone numbers, thus you need to use a proper on which is in your case CHAR(11)/VARCHAR(11).
Then you need to create the constraint as the following:
CREATE TABLE MyTable (
ContactNo varchar(255)
CONSTRAINT CK_ContactNo2
CHECK (ContactNo LIKE '09[0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]')
);
INSERT INTO MyTable(ContactNo) VALUES ('11111') -- Fail
INSERT INTO MyTable(ContactNo) VALUES ('09123456789')-- Succeed
and don't forgot to drop the previous one that if you're no re-creating your table.
You need to have your phone contact in a CHAR(11) and not in any numeric datatype, because the first 0 will be mathematically removed.
As I see, your constraint matche a numerical datatype and not a char string.
With the proper datatype, the constraints give by Sandra Guilep Zouaoui Zandeh is the right one.
You must take a numerical datatype for any columsn only if you need to compute the data. As far as I remenber I have never seen any calculus over phone numbers...
I have another Question comming up, while solving some problems with postgreSQL. Is there any option, to check (in a check statement), if a varchar() contains an upper case character?
(I want that my table only holds Strings with at least one upper case letter.)
Thats how my table look:
CREATE TABLE test(
id integer PRIMARY KEY,
code varchar(255) not null,
CHECK ((char_length(code) >= 10) && check for upperCase?)
);
Does anyone have a tip how to solve this?
Regards,
Lukas
Make sure there are at least one non-lower case character:
CHECK ((char_length(code) >= 10) and code <> lower(code))
One method is a regular expression:
CHECK ((char_length(code) >= 10) and code ~ '[A-Z]')
I am having a problem with a check constraint in Oracle SQL Developer with Oracle 11g Express Edition.
I want to check if my postal code which is stored as CHAR just contains numbers and no other signs.
Tried various possibilities but nothing worked...
PLZ VARCHAR(5) NOT NULL
ADD CONSTRAINT TC_PLZ CHECK (PLZ LIKE '[0-9][0-9][0-9][0-9][0-9]')
Thanks and best regards,
Michael
Use regexp_like():
ADD CONSTRAINT TC_PLZ CHECK ( regexp_like(PLZ, '^[0-9]{5}$') )
Oracle -- like most databases -- only supports the ANSI standard wildcards in LIKE. These are % for zero or more characters and _ for exactly one character.
Regular expressions are much more powerful (although generally slower).
This might be a bit more efficient:
ADD CONSTRAINT TC_PLZ CHECK (translate(PLZ, '0123456789', '000000000') = '00000')
although I would go with the regular expression for clarity.
If you want to use regular expression patterns you need to use a regex function in the CHECK constraint. This will work:
create table t23 (
PLZ VARCHAR(5) NOT NULL
, CONSTRAINT TC_PLZ CHECK (regexp_LIKE(plz, '^[0-9]{5}$'))
);
Although there's no need for regex; here's an alternative implementation:
create table t42 (
PLZ NUMBER(5,0) NOT NULL
, CONSTRAINT T42_PLZ CHECK (length(plz)=5)
);
It's good practice to store numeric values using the correct datatype.
Check out this LiveSQL demo.
As #MT0 points out, the numeric implementation is not correct if a valid value can start with a leading zero. My purist data modeller persona states that values which must be a fixed number of digits should start at 10000 (for five digit values). However, I must admit I know of one system that did permit leading zeroes in a "numeric" field; they compounded this by allowing variable level values, which meant code 0300 identified something different from 00300. What larks!