I want to insert Japanese characters into a VARCHAR2 column type without changing this type to NVARCHAR.
Is it possible ?
Here are the characteristics of my DB (and without changing these characteristics too)
Thank you for help.
Related
we are using Oracle 19c
there are setting in nls_database_parameters
nls_nchar_characterset is UTF8
nls_charchterset is WE8ISO8859P15
I have a table with one column of varchar2 and another column of nvarchar2
I try to insert in both column the same letter,non english ,for example ş and it is not wotking but if I try another non english letter in my language like ž then is is working in both columns. Another colleagues of mine can not insert any letter correctly using the same database user. I don't understand this behavior,what defines what you can insert as national character?
we receive a big list of different cities in different languages. What is the best way to insert all of them correctly?
Is it possible to declare a UTF-8 CLOB if the database is set up with the following character sets?
PARAMETER VALUE
NLS_CHARACTERSET CL8ISO8859P5
NLS_NCHAR_CHARACTERSET AL16UTF16
I tried passing a charset name to the declaration, but it looks like it can only accept references to character sets of other objects.
declare
clob_1 clob character set "AL32UTF8";
begin
null;
end;
/
I don't think this is possible, see PL/SQL Language Fundamentals
PL/SQL uses the database character set to represent:
Stored source text of PL/SQL units
Character values of data types CHAR, VARCHAR2, CLOB, and LONG
So, in your case you have to use NCLOB which uses AL16UTF16 or try a workaround with BLOB. However, this might become cumbersome.
As far as I can tell, you can't do that.
Database character set is defined during database creation (and can't be changed unless you recreate the database) and all character datatype columns store data in that character set.
Perhaps you could try with NCLOB data type, where "N" represents "national character set" and it'll store Unicode character data.
Unicode is a universal encoded character set that can store
information in any language using a single character set
Recently I came across a unicode character (\u2019) in a database table column while parsing using Python.
Question: What are the reasons that can result in unicode characters showing up in the database table? Is it data entry issue?
Appreciate any input.
When you set up your Oracle Database you choose a character set which will be used in the SQL char datatypes (char, varchar2 etc).
Suppose you chose your character set and you have a table with a column of VARCHAR2 type. Suddenly you need to store some string with non-ASCII symbols not supported by your database (chosen character set). You may convert this string into ASCII string by calling ASCIISTR function for example and store it in your VARCHAR2 column (but it's not a good idea because many SQL built-in functions don't understand '\u2019' (they think it's just 6 symbols)). That's how Unicode may appear in your table column (ASCIISTR converts non-ascii symbols into unicode representation such as '\u2019').
Another option is special Oracle nchar datatypes which were designed to store UNICODE without altering global database settings.
Here is the link with Oracle documentation: https://docs.oracle.com/cd/B19306_01/server.102/b14225/ch6unicode.htm
I am running following query in SQL*Plus
CREATE TABLE tbl_audit_trail (
id NUMBER(11) NOT NULL,
old_value varchar2(255) NOT NULL,
new_value varchar2(255) NOT NULL,
action varchar2(20) CHARACTER SET latin1 NOT NULL,
model varchar2(255) CHARACTER SET latin1 NOT NULL,
field varchar2(64) CHARACTER SET latin1 NOT NULL,
stamp timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
user_id NUMBER(11) NOT NULL,
model_id varchar2(65) CHARACTER SET latin1 NOT NULL,
PRIMARY KEY (id),
KEY idx_action (action)
);
I am getting following error:
action varchar2(20) CHARACTER SET latin1 NOT NULL,
*
ERROR at line 5:
ORA-00907: missing right parenthesis
Can you suggest what am I missing?
The simple answer is that, unlike MySQL, character sets can't be defined at column (or table) level. Latin1 is not a valid Oracle character set either.
Character sets are consistent across the database and will have been specified when you created the database. You can find your character by querying NLS_DATABASE_PARAMETERS,
select value
from nls_database_parameters
where parameter = 'NLS_CHARACTERSET'
The full list of possible character sets is available for 11g r2 and for 9i or you can query V$NLS_VALID_VALUES.
It is possible to use the ALTER SESSION statement to set the NLS_LANGUAGE or the NLS_TERRITORY, but unfortunately you can't do this for the character set. I believe this is because altering the language changes how Oracle would display the stored data whereas changing the character set would change how Oracle stores the data.
When displaying the data, you can of course specify the required character set in whichever client you're using.
Character set migration is not a trivial task and should not be done lightly.
On a slight side note why are you trying to use Latin 1? It would be more normal to set up a new database in something like UTF-8 (otherwise known as AL32UTF8 - don't use UTF8) or UTF-16 so that you can store multi-byte data effectively. Even if you don't need it now it's wise to attempt - no guarantees in life - to future proof your database with no need to migrate in the future.
If you're looking to specify differing character sets for different columns in a database then the better option would be to determine if this requirement is really necessary and to try to remove it. If it is definitely necessary1 then your best bet might be to use a character set that is a superset of all potential character sets. Then, have some sort of check constraint that limits the column to specific hex values. I would not recommend doing this at all, the potential for mistakes to creep in is massive and it's extremely complex. Furthermore, different character sets render different hex values differently. This, in turn, means that you need to enforce that a column is rendered in a specific character, which is impossible as it falls outside the scope of the database.
1. I'd be interested to know the situation
According to provided DDL statement it's some need to use 2 character sets. The implementation of this functionality in Oracle is different from MySQL and done with n* data types like nvarchar2, nchar... Latin1 is similar to some Western European character set that might be default. So you able to define for example "Latin1" (WE**) and some Unicode (UTF8..).
The NVARCHAR2 datatype was introduced by Oracle for databases that want to use Unicode for some columns while keeping another character set for the rest of the database (which uses VARCHAR2). The NVARCHAR2 is a Unicode-only datatype.
The reason you want to use NVARCHAR2 might be that your DB uses a non-Unicode character and you still want to be able to store Unicode data for some columns.
Columns in your example would be able to store the same data, however the byte storage will be different.
What is the difference between varchar and varchar2?
As for now, they are synonyms.
VARCHAR is reserved by Oracle to support distinction between NULL and empty string in future, as ANSI standard prescribes.
VARCHAR2 does not distinguish between a NULL and empty string, and never will.
If you rely on empty string and NULL being the same thing, you should use VARCHAR2.
Currently VARCHAR behaves exactly the same as VARCHAR2. However, the type VARCHAR should not be used as it is reserved for future usage.
Taken from: Difference Between CHAR, VARCHAR, VARCHAR2
Taken from the latest stable Oracle production version 12.2:
Data Types
The major difference is that VARCHAR2 is an internal data type and VARCHAR is an external data type. So we need to understand the difference between an internal and external data type...
Inside a database, values are stored in columns in tables. Internally, Oracle represents data in particular formats known as internal data types.
In general, OCI (Oracle Call Interface) applications do not work with internal data type representations of data, but with host language data types that are predefined by the language in which they are written. When data is transferred between an OCI client application and a database table, the OCI libraries convert the data between internal data types and external data types.
External types provide a convenience for the programmer by making it possible to work with host language types instead of proprietary data formats. OCI can perform a wide range of data type conversions when transferring data between an Oracle database and an OCI application. There are more OCI external data types than Oracle internal data types.
The VARCHAR2 data type is a variable-length string of characters with a maximum length of 4000 bytes. If the init.ora parameter max_string_size is default, the maximum length of a VARCHAR2 can be 4000 bytes. If the init.ora parameter max_string_size = extended, the maximum length of a VARCHAR2 can be 32767 bytes
The VARCHAR data type stores character strings of varying length. The first 2 bytes contain the length of the character string, and the remaining bytes contain the string. The specified length of the string in a bind or a define call must include the two length bytes, so the largest VARCHAR string that can be received or sent is 65533 bytes long, not 65535.
A quick test in a 12.2 database suggests that as an internal data type, Oracle still treats a VARCHAR as a pseudotype for VARCHAR2. It is NOT a SYNONYM which is an actual object type in Oracle.
SQL> select substr(banner,1,80) from v$version where rownum=1;
Oracle Database 12c Enterprise Edition Release 12.2.0.1.0 - 64bit Production
SQL> create table test (my_char varchar(20));
Table created.
SQL> desc test
Name Null? Type
MY_CHAR VARCHAR2(20)
There are also some implications of VARCHAR for ProC/C++ Precompiler options. For programmers who are interested, the link is at: Pro*C/C++ Programmer's Guide
After some experimentation (see below), I can confirm that as of September 2017, nothing has changed with regards to the functionality described in the accepted answer:-
Rextester demo for Oracle 11g:
Empty strings are inserted as NULLs for both VARCHAR
and VARCHAR2.
LiveSQL demo for Oracle 12c: Same results.
The historical reason for these two keywords is explained well in an answer to a different question.
VARCHAR can store up to 2000 bytes of characters while VARCHAR2 can store up to 4000 bytes of characters.
If we declare datatype as VARCHAR then it will occupy space for NULL values. In the case of VARCHAR2 datatype, it will not occupy any space for NULL values. e.g.,
name varchar(10)
will reserve 6 bytes of memory even if the name is 'Ravi__', whereas
name varchar2(10)
will reserve space according to the length of the input string. e.g., 4 bytes of memory for 'Ravi__'.
Here, _ represents NULL.
NOTE: varchar will reserve space for null values and varchar2 will not reserve any space for null values.
Currently, they are the same. but previously
Somewhere on the net, I read that,
VARCHAR is reserved by Oracle to support distinction between NULL and empty string in future, as ANSI standard prescribes.
VARCHAR2 does not distinguish between a NULL and empty string, and never will.
Also,
Emp_name varchar(10) - if you enter value less than 10 digits then remaining space cannot be deleted. it used total of 10 spaces.
Emp_name varchar2(10) - if you enter value less than 10 digits then remaining space is automatically deleted