What s the difference between VARCHAR and CHAR

Question

What s the difference between VARCHAR and CHAR in MySQL   I am trying to store MD5 hashes

User · Accepted Answer

VARCHAR is variable-length   CHAR is fixed length   If your content is a fixed size  you ll get better performance with CHAR   See the MySQL page on CHAR and VARCHAR Types for a detailed explanation  be sure to also read the comments

User · Answer

Varchar cuts off trailing spaces if the entered characters is shorter than the declared length  while char will not  Char will pad spaces and will always be the length of the declared length  In terms of efficiency  varchar is more adept as it trims characters to allow more adjustment  However  if you know the exact length of char  char will execute with a bit more speed

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Char or varchar- it is used to enter texual data where the length can be indicated in brackets Eg- name char  20

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CHAR   Used to store character string value of fixed length  The maximum no  of characters the data type can hold is 255 characters  It s 50  faster than VARCHAR  Uses static memory allocation    VARCHAR   Used to store variable length alphanumeric data  The maximum this data type can hold is up to   Pre-MySQL 5 0 3  255 characters  Post-MySQL 5 0 3  65 535 characters shared for the row   It s slower than CHAR  Uses dynamic memory allocation

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Char has a fixed length  supports 2000 characters   it is stand for character is a data type   Varchar has a variable length  supports 4000 characters

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CHAR is fixed length and VARCHAR is variable length  CHAR always uses the same amount of storage space per entry  while VARCHAR only uses the amount necessary to store the actual text

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CHAR is a fixed length field  VARCHAR is a variable length field  If you are storing strings with a wildly variable length such as names  then use a VARCHAR  if the length is always the same  then use a CHAR because it is slightly more size-efficient  and also slightly faster

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What s the difference between VARCHAR and CHAR in MySQL    To already given answers I would like to add that in OLTP systems or in systems with frequent updates consider using CHAR even for variable size columns because of possible VARCHAR column fragmentation during updates      I am trying to store MD5 hashes    MD5 hash is not the best choice if security really matters  However  if you will use any hash function  consider BINARY type for it instead  e g  MD5 will produce 16-byte hash  so BINARY 16  would be enough instead of CHAR 32  for 32 characters representing hex digits  This would save more space and be performance effective

User · Answer

The char is a fixed-length character data type  the varchar is a variable-length character data type   Because char is a fixed-length data type  the storage size of the char value is equal to the maximum size for this column  Because varchar is a variable-length data type  the storage size of the varchar value is the actual length of the data entered  not the maximum size for this column   You can use char when the data entries in a column are expected to be the same size  You can use varchar when the data entries in a column are expected to vary considerably in size

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CHAR      Supports both Character  amp  Numbers  Supports 2000 characters  Fixed Length    VARCHAR     Supports both Character  amp  Numbers  Supports 4000 characters  Variable Length    any comments

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according to High Performance MySQL book       VARCHAR stores variable-length character strings and is the most common string data type  It can require less storage space than   fixed-length types  because it uses only as much space as it needs    i e   less space is used to store shorter values   The exception is a   MyISAM table created with ROW FORMAT FIXED  which uses a fixed amount   of space on disk for each row and can thus waste space  VARCHAR helps   performance because it saves space        CHAR is fixed-length  MySQL always allocates enough space for the specified number of characters  When storing a CHAR value  MySQL   removes any trailing spaces   This was also true of VARCHAR in MySQL   4 1 and older versions   CHAR and VAR CHAR were logically identical and differed only in storage format   Values are padded with spaces as   needed for comparisons

User · Answer

A CHAR x  column can only have exactly x characters  A VARCHAR x  column can have up to x characters   Since your MD5 hashes will always be the same size  you should probably use a CHAR   However  you shouldn t be using MD5 in the first place  it has known weaknesses  Use SHA2 instead  If you re hashing passwords  you should use bcrypt

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CHAR Vs VARCHAR  CHAR is used for Fixed Length Size Variable VARCHAR is used for Variable Length Size Variable   E g   Create table temp  City CHAR 10   Street VARCHAR 10     Insert into temp values  Pune   Oxford     select length city   length street  from temp    Output will be  length City           Length street  10                    6   Conclusion  To use storage space efficiently must use VARCHAR Instead CHAR if variable length is variable

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In most RDBMSs today  they are synonyms   However for those systems that still have a distinction  a CHAR field is stored as a fixed-width column   If you define it as CHAR 10   then 10 characters are written to the table  where  padding   typically spaces  is used to fill in any space that the data does not use up   For example  saving  bob  would be saved as   bob  7 spaces    A VARCHAR  variable character  column is meant to store data without wasting the extra space that a CHAR column does   As always  Wikipedia speaks louder

[sql] What's the difference between VARCHAR and CHAR?

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