What is the difference between varchar and nvarchar

Question

Is it just that nvarchar supports multibyte characters  If that is the case  is there really any point  other than storage concerns  to using varchars

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You re right  nvarchar stores Unicode data while varchar stores single-byte character data  Other than storage differences  nvarchar requires twice the storage space as varchar   which you already mentioned  the main reason for preferring nvarchar over varchar would be internationalization  i e  storing strings in other languages

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varchar  Variable-length  non-Unicode character data  The database collation determines which code page the data is stored using   nvarchar  Variable-length Unicode character data  Dependent on the database collation for comparisons   Armed with this knowledge  use whichever one matches your input data  ASCII v  Unicode

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My two cents   Indexes can fail when not using the correct datatypes  In SQL nbsp Server  When you have an index over a VARCHAR column and present it a Unicode String  SQL nbsp Server does not make use of the index  The same thing happens when you present a BigInt to a indexed-column containing SmallInt  Even if the BigInt is small enough to be a SmallInt  SQL nbsp Server is not able to use the index  The other way around you do not have this problem  when providing SmallInt or Ansi-Code to an indexed BigInt ot NVARCHAR column   Datatypes can vary between different DBMS s  DataBase Management System   Know that every database has slightly different datatypes and VARCHAR does not means the same everywhere  While SQL nbsp Server has VARCHAR and NVARCHAR  an Apache Derby database has only VARCHAR and there VARCHAR is in Unicode

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An nvarchar column can store any Unicode data  A varchar column is restricted to an 8-bit codepage  Some people think that varchar should be used because it takes up less space  I believe this is not the correct answer  Codepage incompatabilities are a pain  and Unicode is the cure for codepage problems  With cheap disk and memory nowadays  there is really no reason to waste time mucking around with code pages anymore   All modern operating systems and development platforms use Unicode internally  By using nvarchar rather than varchar  you can avoid doing encoding conversions every time you read from or write to the database  Conversions take time  and are prone to errors  And recovery from conversion errors is a non-trivial problem   If you are interfacing with an application that uses only ASCII  I would still recommend using Unicode in the database  The OS and database collation algorithms will work better with Unicode  Unicode avoids conversion problems when interfacing with other systems  And you will be preparing for the future  And you can always validate that your data is restricted to 7-bit ASCII for whatever legacy system you re having to maintain  even while enjoying some of the benefits of full Unicode storage

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Since SQL Server 2019 varchar columns support UTF-8 encoding  Thus  from now on  the difference is size  In a database system that translates to difference in speed  Less size   Less IO   Less Memory   More speed in general  Read the article above for the numbers  Go for varchar in UTF8 from now on  Only if you have big percentage of data with characters in ranges 2048 - 16383 and 16384     65535 - you will have to measure

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Follow Difference Between Sql Server VARCHAR and NVARCHAR Data Type  Here you could see in a very descriptive way   In generalnvarchar stores data as Unicode  so  if you re going to store multilingual data  more than one language  in a data column you need the N variant

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I always use nvarchar as it allows whatever I m building to withstand pretty much any data I throw at it  My CMS system does Chinese by accident  because I used nvarchar  These days  any new applications shouldn t really be concerned with the amount of space required

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Mainly nvarchar stores Unicode characters and varchar stores non-Unicode characters    Unicodes  means 16-bit character encoding scheme allowing characters from lots of other languages like Arabic  Hebrew  Chinese  Japanese  to be encoded in a single character set   That means unicodes is using 2 bytes per character to store and nonunicodes uses only one byte per character to store  Which means unicodes need double capacity to store compared to non-unicodes

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nvarchar is safe to use compared to varchar in order to make our code error free  type mismatching  because nvarchar allows unicode characters also  When we use where condition in SQL Server query and if we are using   operator  it will throw error some times  Probable reason for this is our mapping column will be difined in varchar  If we defined it in nvarchar this problem my not happen  Still we stick to varchar and avoid this issue we better use LIKE key word rather than

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I had a look at the answers and many seem to recommend to use nvarchar over varchar  because space is not a problem anymore  so there is no harm in enabling Unicode for little extra storage  Well  this is not always true when you want to apply an index over your column  SQL Server has a limit of 900 bytes on the size of the field you can index  So if you have a varchar 900  you can still index it  but not varchar 901   With nvarchar  the number of characters is halved  so you can index up to nvarchar 450   So if you are confident you don t need nvarchar  I don t recommend using it   In general  in databases  I recommend sticking to the size you need  because you can always expand  For example  a colleague at work once thought that there is no harm in using nvarchar max  for a column  as we have no problem with storage at all  Later on  when we tried to apply an index over this column  SQL Server rejected this  If  however  he started with even varchar 5   we could have simply expanded it later to what we need without such a problem that will require us to do a field migration plan to fix this problem

User · Answer

Although NVARCHAR stores Unicode  you should consider by the help of collation also you can use VARCHAR and save your data of your local languages   Just imagine the following scenario   The collation of your DB is Persian and you save a value like        Persian writing of Ali  in the VARCHAR 10  datatype  There is no problem and the DBMS only uses three bytes to store it    However  if you want to transfer your data to another database and see the correct result your destination database must have the same collation as the target which is Persian in this example   If your target collation is different  you see some question marks    in the target database   Finally  remember if you are using a huge database which is for usage of your local language  I would recommend to use location instead of using too many spaces   I believe the design can be different  It depends on the environment you work on

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I have to say here  I realise that I m probably going to open myself up to a slating    but surely the only time when NVARCHAR is actually more useful  notice the more there   than VARCHAR is when all of the collations on all of the dependant systems and within the database itself are the same      If not then collation conversion has to happen anyway and so makes VARCHAR just as viable as NVARCHAR   To add to this  some database systems  such as SQL Server  before 2012  have a page size of approx  8K   So  if you re looking at storing searchable data not held in something like a TEXT or NTEXT field then VARCHAR provides the full 8k s worth of space whereas NVARCHAR only provides 4k  double the bytes  double the space    I suppose  to summarise  the use of either is dependent on    Project or context Infrastructure Database system

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I would say  it depends   If you develop a desktop application  where the OS works in Unicode  like all current Windows systems  and language does natively support Unicode  default strings are Unicode  like in Java or C    then go nvarchar   If you develop a web application  where strings come in as UTF-8  and language is PHP  which still does not support Unicode natively  in versions 5 x   then varchar will probably be a better choice

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Jeffrey L Whitledge with  47000 reputation score recommends usage of nvarchar  Solomon Rutzky with with  33200 reputation score recommends  Do NOT always use NVARCHAR  That is a very dangerous  and often costly  attitude   approach   What are the main performance differences between varchar and nvarchar SQL Server data types   https   www sqlservercentral com articles disk-is-cheap-orly-4    Both persons of such a high reputation  what does a learning sql server database developer choose   There are many warnings in answers and comments about performance issues if you are not consistent in choices   There are comments pro con nvarchar for performance    There are comments pro con varchar for performance   I have a particular requirement for a table with many hundreds of columns  which in itself is probably unusual     I m choosing varchar to avoid going close to the 8060 byte table record size limit of SQL server 2012    Use of nvarchar  for me  goes over this 8060 byte limit   I m also thinking that I should match the data types of the related code tables to the data types of the primary central table   I have seen use of varchar column at this place of work  South Australian Government  by previous experienced database developers  where the table row count is going to be several millions or more  and very few nvarchar columns  if any  in these very large tables   so perhaps the expected data row volumes becomes part of this decision

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The main difference between Varchar n  and nvarchar n  is    Varchar  Variable-length  non-Unicode character data  size is upto 8000   1 It is a variable length data type   Used to store non-Unicode characters Occupies 1 byte of space for each character     Nvarchar Variable-length Unicode character data   1 It is a variable-length data type  2 Used to store Unicode characters    Data is stored in a Unicode encoding  Every language is supported   for example the languages Arabic  German Hindi etc and so on

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nvarchar stores data as Unicode  so  if you re going to store multilingual data  more than one language  in a data column you need the N variant

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If a single byte is used to store a character  there are 256 possible combinations  and thereby you can save 256 different characters  Collation is the pattern which defines the characters and the rules by which they are compared and sorted  1252  which is the Latin1  ANSI   is the most common  Single-byte character sets are also inadequate to store all the characters used by many languages  For example  some Asian languages have thousands of characters  so they must use two bytes per character  Unicode standard When systems using multiple code pages are used in a network  it becomes difficult to manage communication  To standardize things  the ISO and Unicode consortium introduced the Unicode  Unicode uses two bytes to store each character  That is 65 536 different characters can be defined  so almost all the characters can be covered with Unicode  If two computers use Unicode  every symbol will be represented in the same way and no conversion is needed - this is the idea behind Unicode  SQL Server has two categories of character datatypes   non-Unicode  char  varchar  and text  Unicode  nchar  nvarchar  and ntext   If we need to save character data from multiple countries  always use Unicode

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It depends on how Oracle was installed  During the installation process  the NLS CHARACTERSET option is set  You may be able to find it with the query SELECT value  FROM sys props  WHERE name    NLS CHARACTERSET    If your NLS CHARACTERSET is a Unicode encoding like UTF8  great  Using VARCHAR and NVARCHAR are pretty much identical  Stop reading now  just go for it  Otherwise  or if you have no control over the Oracle character set  read on   VARCHAR     Data is stored in the NLS CHARACTERSET encoding  If there are other database instances on the same server  you may be restricted by them  and vice versa  since you have to share the setting  Such a field can store any data that can be encoded using that character set  and nothing else  So for example if the character set is MS-1252  you can only store characters like English letters  a handful of accented letters  and a few others  like     and       Your application would be useful only to a few locales  unable to operate anywhere else in the world  For this reason  it is considered A Bad Idea   NVARCHAR     Data is stored in a Unicode encoding  Every language is supported  A Good Idea   What about storage space  VARCHAR is generally efficient  since the character set   encoding was custom-designed for a specific locale  NVARCHAR fields store either in UTF-8 or UTF-16 encoding  base on the NLS setting ironically enough  UTF-8 is very efficient for  Western  languages  while still supporting Asian languages  UTF-16 is very efficient for Asian languages  while still supporting  Western  languages  If concerned about storage space  pick an NLS setting to cause Oracle to use UTF-8 or UTF-16 as appropriate   What about processing speed  Most new coding platforms use Unicode natively  Java   NET  even C   std  wstring from years ago   so if the database field is VARCHAR it forces Oracle to convert between character sets on every read or write  not so good  Using NVARCHAR avoids the conversion   Bottom line  Use NVARCHAR  It avoids limitations and dependencies  is fine for storage space  and usually best for performance too

User · Answer

nVarchar will help you to store Unicode characters  It is the way to go if you want to store localized data

[sql-server] What is the difference between varchar and nvarchar?

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