Char vs Varchar

Hi
Can any one tell what is the difference between CHAR & VARCHAR2.....
Cheers,
Balaji.C

Did you search before posting here?
This might be useful for you. Go through this
http://asktom.oracle.com/pls/ask/f?p=4950:8:::::F4950_P8_DISPLAYID:1542606219593

Similar Messages

Difference between char and varchar, also the difference between varchar2

Hi,
Can anyone explain me the difference between char and varchar, and also the difference between varchar and varchar2...

Varchar2 is variable width character data type, so if you define column with width 20 and insert only one character to tis column only, one character will be stored in database. Char is not variable width so when you define column with width 20 and insert one character to this column it will be right padded with 19 spaces to desired length, so you will store 20 characters in the dattabase (follow the example 1). Varchar data type from Oracle 9i is automaticlly promoted to varchar2 (follow example 2)
Example 1:
SQL> create table tchar(text1 char(10), text2 varchar2(10))
2 /
Table created.
SQL> insert into tchar values('krystian','krystian')
2 /
1 row created.
SQL> select text1, length(text1), text2, length(text2)
2 from tchar
3 /
TEXT1 LENGTH(TEXT1) TEXT2 LENGTH(TEXT2)
krystian 10 krystian 8
Example 2:
create table tvarchar(text varchar(10))
SQL> select table_name,column_name,data_type
2 from user_tab_columns
3 where table_name = 'TVARCHAR'
4 /
TABLE_NAME COLUMN_NAME DATA_TYPE
TVARCHAR TEXT VARCHAR2
Best Regards
Krystian Zieja / mob

CHAR to VARCHAR in conversion

Hello,
Is this issue still valid with the latest OMWB release.
When converting from Informix Online to Oracle 8i:
"Data type issue, here problem comes converting chars to varchars as chars are padded and may not work in indexes, so you have to trim them afterwards."
Thanks
Mike

We had a lots of cases in which CHAR(n) is defined and we wanted to convert all these
CHAR(n)s to VARCHAR2(n). But since CHAR(n) datatype will allocated the extra spaces
even if the length of the string is less than 'n'; we wanted to change that.
We realized that after migration all the VARCHAR2(n) are still padded with extra spaces.
Thanks

SQL - char vs varchar

Does it make sense to set the entity fields username password, to be 48 chars of length and to be CHAR instead of varchar ?
Is it better to choose the former in the presence of an index ?
How does CHAR perform when the encoding of the strings in the RDBMS is UTF (for those who dont know, this is a variable length encoding, e.g. japanese chars can be encoded in UTF-8, 24bit code points could be encoded in UTF16, and so on) ?
What does make sense ? char or varchar for username and password for speed searching ?
Thanks

Does it make sense to set the entity fields username password, to be 48 chars of length and to be CHAR instead of varchar ?
Is it better to choose the former in the presence of an index ?
How does CHAR perform when the encoding of the strings in the RDBMS is UTF (for those who dont know, this is a variable length encoding, e.g. japanese chars can be encoded in UTF-8, 24bit code points could be encoded in UTF16, and so on) ?
What does make sense ? char or varchar for username and password for speed searching ?
Thanks

Joining table using CHAR and VARCHAR data type as indicator

Hi All,
I would like to join 3 tables together but I'm unable to get a perfect concordance (using =) between CHAR and VARCHAR data type.
Does a command exist to get impartially all data treated as CHAR or VARCHAR ?
Thanks in advance for your help !

You want the database to perform with such a crappy database design? Good luck with that.. Instead, you need to look at why you are NOT using surrogate integer based keys for your data tables..
Thank you,
Tony Miller
Webster, TX
If vegetable oil is made of vegetables, what is baby oil made of?
If this question is answered, please mark the thread as closed and assign points where earned..

Char and varchar

There are great differences between a char(1999) and varchar2(1999) as the CHAR is always 1999 characters long physically AND logically. the varchar is physically 1999 bytes but logically can be any size in between 0 and 1999.
What does it mean when this sentence says that char is 1999 long physically and logically ,,,,,,and varchar is 1999 long physically and logically could be between 0 and 1999 .
for char i guess it means 1999 bytes are alocatted in memory on the disk ? And all that memory is taken up !!!!
for varchar how is it interpreted ?
thanks!!!!

Hi,
I will try to explain in simpe way, if you perform and see the steps provided in the link
[http://www.orafaq.com/wiki/SQL_FAQ#What_is_the_difference_between_VARCHAR.2C_VARCHAR2_and_CHAR_data_types.3F]
then check the user_tab_columns table and check the column data_length, this displays the length of the Column by which it validates length.
Then try and see the char_test table with single "A" and check the dump of that Column as he said that spaces are padded and memory is fully filled.
When compared to Varchar the memory is dynamically filled as need (based on Updated), internally the it allocates the required memory using the realloc() function or extends the memory further (not sure about the function).
you have keed in mind that it stored the length of the data along with the Column.
When you compare with the varchar, it will not stored or will not pad the spaces in the remaing memory, so that can be utlizied by remaining blocks of data in the Row.
- Pavan Kumar N

Char vs Varchar 2

Running Windows Server 2008 x 64
I am creating tables holding people, provincial names ,etc.
eg County = Hertfordshire
UserName = Bob Allen Quickstep
blah blah
The Name features would be set to say 255 characters.
What difference does it make choosing Char VS VarChar_2??*
Data will be imported from Excel spreadsheets

Clive_S wrote:
Are you saying that VarChar is more efficient in saving the data and there is no other difference??
I am just saying varchar2 data type would use less space compared to char data type if value is of variable length.
Should you still need to set a 'template' size for input??I did not understand the question.
Regards
Anurag

Data type difference of char and varchar will affect the searching result?

Hi,
My issue is tht i have created an item in db as char(20) while creating EO for tht particular table, data type for tht item attribute is by default coming as string. wen i search from table based on tht item, no rows are returned.So can anyone help me to solve this?
Thanks
Harsha

Hi,
My requirement is having a page with search region and result region. Search region shud be done programmatically. In the search region im having a lov item, radion group item, date and poplist. poplist is having, for eg., list of countries which is fetched from lookupcode. i have to buttons "go" and "clear". wen i select any of the items and click go btn results shud be displayed in a multiselect table which is updatable. Since im using updatable table im using EO which is linked to tht search region. So my issue is tht wen i select a value from poplist and click "go" btn no rows are returned, even if rows based on tht selected values are present in the table. Wht i did is tht wen i click go btn, im taking the value from tht poplist im callin VOImpl to implement the search. The value which i fetched from the poplist is available in tht method to search also. Also when i activated tht console o/p it is showing the query as country_id = :1. But it is not selecting any rows. I think im clear now, like y EO is used and all. Please help me.
Thanks
Harsha.

Char and varchar performance issues

I am creating a child table with varchar2(4) column which takes the value from parent table which has char(4) column.
pls give ur suggestion that child table also should have char(4) as like parent table or having varchar2(4) is good one.? which one gives better peformance?
S

AswinGousalya wrote:
I am creating a child table with varchar2(4) column which takes the value from parent table which has char(4) column. You mean like a Primary Key and Foreign key relation? In that case the data type must be the same for both the columns.
pls give ur suggestion that child table also should have char(4) as like parent table or having varchar2(4) is good one.? which one gives better peformance? If you are going to stick to parent being CHAR(4) then child must be definitely be CHAR(4).
Whats the difference between CHAR and VARCHAR2 data type?
CHAR is a fixed length data type and VARCHAR2 is a variable length. What does that mean? Lets say you have a CHAR(4) and VARCHAR2(4) column. You are storing the word 'AA' in both. Oracle will allocate 4 byte of space for CHAR column and just 2 byte of space to VARCHAR2 column. i.e. as i already said CHAR is a fixed length string. So the 'AA' is actually stored as 'AA ' (AA<two blank spaces>).
So the next question is which of the two is better? You cant compare them, they are just two different tools provided by oracle. Use which is best suited for you.

[BO XI 3.1] Error with char/varchar with MySQL

We are using Business Objects with a MySQL database underneath. The ODBC driver installed on the Business Objects server is configured as shown below:
[BIRDDBD1]
Description = BIRDDBD1
Driver      = MySQL
SERVER      = xx.xx.xx.xx
USER        = xxxxx
PASSWORD    = xxxxx
PORT        = 3306
DATABASE    = IAS
Option      = 3
The users use InfoView to create Web Intelligence reports. As soon as at least one attribute of datatype char or varchar is contained in a report, we get the following error message:
A database error occured. The database error text is: [MySQL][ODBC 3.51 Driver][mysqld-5.1.31sp1-enterprise-gpl-advanced-log]Restricted data type attribute violation. (WIS 10901)
When a report solely contains number and date attributes, we get a proper report result and do not get any error message.
Trying to get data (also char or varchar data!) within the Business Objects Designer does not cause any problems!
Could you please advice?
Martin

Hi,
this can be. There are some changes in the Permissions from Rel.2 to XI 3.x
I know that under 3.0 there was a Bug with Sheduling Permissions. Do you have any FixPack applied for your 3.0 Installation ?
BTW: I would recommend upgrading to 3.1 SP2 (latest version). There are a lot of Bugs in 3.0
Regards
-Seb.

Difference between CHAR and VARCHAR2 datatype

Difference between CHAR and VARCHAR2 datatype
CHAR datatype
If you have an employee name column with size 10; ename CHAR(10) and If a column value 'JOHN' is inserted, 6 empty spaces will be inserted to the right of the value. If this was a VARCHAR column; ename VARCHAR2(10). How would it handle the column value 'JOHN' ?

The CHAR datatype stores fixed-length character strings, and Oracle compares CHAR values using blank-padded comparison semantics.
Where as the VARCHAR2 datatype stores variable-length character strings, and Oracle compares VARCHAR2 values using nonpadded comparison semantics.
This is important when comparing or joining on the columns having these datatypes;
SQL*Plus: Release 10.2.0.1.0 - Production on Pzt Au 6 09:16:45 2007
Copyright (c) 1982, 2005, Oracle. All rights reserved.
SQL> conn hr/hr
Connected.
SQL> set serveroutput on
SQL> DECLARE
2 last_name1 VARCHAR2(10) := 'TONGUC';
3 last_name2 CHAR(10) := 'TONGUC';
4 BEGIN
5 IF last_name1 = last_name2 THEN
6 DBMS_OUTPUT.PUT_LINE ( '-' || last_name1 || '- is equal to -' || last_name2
|| '-');
7 ELSE
8 DBMS_OUTPUT.PUT_LINE ( '-' || last_name1 || '- is NOT equal to -' || last_n
ame2 || '-');
9 END IF;
10 END;
11 /
-TONGUC- is NOT equal to -TONGUC -
PL/SQL procedure successfully completed.
SQL> DECLARE
2 last_name1 CHAR(6) := 'TONGUC';
3 last_name2 CHAR(10) := 'TONGUC';
4 BEGIN
5 IF last_name1 = last_name2 THEN
6 DBMS_OUTPUT.PUT_LINE ( '-' || last_name1 || '- is equal to -' || last_name2
|| '-');
7 ELSE
8 DBMS_OUTPUT.PUT_LINE ( '-' || last_name1 || '- is NOT equal to -' || last_n
ame2 || '-');
9 END IF;
10 END;
11 /
-TONGUC- is equal to -TONGUC -
PL/SQL procedure successfully completed.
Also you may want to read related asktom thread - "Char Vs Varchar" http://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:1542606219593
and http://tahitiviews.blogspot.com/2007/05/less-is-more-more-or-less.html
Best regards.

Bug regarding not filling in length of varchar field in logical model?

I successfully was able to create a logical model, engineer to relational, and generate DDL from this.
However, I found after generating the DDL and attempting to run it, I received errors in creation of some tables saying "missing left parentheses."
After going back and checking, it turned out that I was somehow able to define columns of type varchar in the logical model without putting in a length for the column. Data Modeler generated the DDL for the table looking something like this:
CREATE TABLE LIC_TYPE
    ID     INTEGER NOT NULL ,
    CODE   VARCHAR2 (1024 BYTE) NOT NULL ,
    "DESC" VARCHAR2
LOGGING ;
(for the DESC column) -- which then throws an error.
Should DDL generation should throw a warning when attempting to create CHAR or VARCHAR columns without a length instead of generating the DDL with no errors? Or is this intended functionality?
Using SQL Data Modeler/SQL Developer 4.1 EA2.

Hi,
Thanks for reporting this problem. I've logged an enhancement request.
David

To reach the end of a varchar

i want to remove last character of my varchar variable.
is there any command as to reach a char of varchar. such as charAt() in java.
so, i have a varchar variable. and its last character is ','. i must remove it. how can i do this?
thanx

What if indeed? That's not how I read the sentence otherwise I wouldn't have suggested it.
To me it sounds like I have a trailing comma at the end of my string, how do I get rid of it?
Clearly the OP is Java orientated and the Java String class doesn't appear to have an equivalent of the LTRIM functions (it has a trim method but that doesn't take the character to trim as an argument, it only does whitespace).
So makes me think that he might not be know that's the question to ask, because they have no equivalent
But yes, it may be. We can only hope the OP comes back and tells us.

Diff char in variable and procedure call

I understand the difference between Char en Varchar. What I don't understand is the different behaviour of Char when assigning a plain variable and when assigning a procedure call variable. I've created this sample code:
declare
v char;
procedure t (i char) as
begin
    if i = ' ' then
      dbms_output.put_line('ok');
    else
      dbms_output.put_line('else');
    end if;
end;
begin
v := '';
t('');
t(' ');
t(null);
t(v);
end;
else
ok
else
ok
PL/SQL-procedure is geslaagd.The first (t('')) call and last (t(v)) call I think should result in the same answer, but apearantly, when v is assigned, a space is passed into the variable (sounds correct according to documentation), but when i is directly assigned, a null is assigned, rather than a space.
Does anyone know what the explanation is for this behaviour?
Thanx,
Lennert
ps, I'm not looking for a solution or a work around, I'm just interested in the background.
pps, I'm running O8174 on HPUX

x CHAR;
It's default length is one but if you don't assign a value, it's value is null and its length is null. The empty string ('') is not null, so the assignment x := '' will assign a value of space, since PL/SQL pads with spaces to fill the length.
PROCEDURE test is
x char;
BEGIN
dbms_output.put_line('x = >' || x || '< , the length of x is: ' || to_char(length(x)));
x := null;
dbms_output.put_line('x = >' || x || '< , the length of x is: ' || to_char(length(x)));
x := '';
dbms_output.put_line('x = >' || x || '< , the length of x is: ' || to_char(length(x)));
dbms_output.put_line(to_char(ascii(x)));
x := ' ';
dbms_output.put_line('x = >' || x || '< , the length of x is: ' || to_char(length(x)));
END test;
SQL> execute test.proc1
x = >< , the length of x is:
x = >< , the length of x is:
x = > < , the length of x is: 1
32
x = > < , the length of x is: 1

Why getBytes for VARCHAR type return byte array in UTF8 Codemap?

I have found that the getBytes method is double speed than getString method for CHAR and VARCHAR data type in the ResultSet object,when I am process Chinese I met this problem.

I have found that the getBytes method is double speed than getString method for CHAR and VARCHAR data type in the ResultSet object,when I am process Chinese I met this problem.

Char vs Varchar

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