Character types
Character data types include CHAR (character) and VARCHAR (character varying).
Storage and ranges
CHAR and VARCHAR data types are defined in terms of bytes, not characters. A CHAR column can only contain single-byte characters, so a CHAR(10) column can contain a string with a maximum length of 10 bytes. A VARCHAR can contain multibyte characters, up to a maximum of four bytes per character. For example, a VARCHAR(12) column can contain 12 single-byte characters, 6 two-byte characters, 4 three-byte characters, or 3 four-byte characters.
| Name | Storage | Range (width of column) |
|---|---|---|
| CHAR or CHARACTER | Length of string, including trailing blanks (if any) | 4096 bytes |
| VARCHAR or CHARACTER VARYING | 4 bytes + total bytes for characters, where each character can be 1 to 4 bytes. | 65535 bytes (64K -1) |
Topics
CHAR or CHARACTER
Use a CHAR or CHARACTER column to store fixed-length strings. These strings are padded with blanks, so a CHAR(10) column always occupies 10 bytes of storage.
char(10)
A CHAR column without a length specification results in a CHAR(1) column.
VARCHAR or CHARACTER VARYING
Use a VARCHAR or CHARACTER VARYING column to store variable-length strings with a fixed limit. These strings are not padded with blanks, so a VARCHAR(120) column consists of a maximum of 120 single-byte characters, 60 two-byte characters, 40 three-byte characters, or 30 four-byte characters.
varchar(120)
Significance of trailing blanks
Both CHAR and VARCHAR data types store strings up to n bytes in length. An attempt to store a longer string into a column of these types results in an error. However, if the extra characters are all spaces (blanks), the string is truncated to the maximum length. If the string is shorter than the maximum length, CHAR values are padded with blanks, but VARCHAR values store the string without blanks.
Trailing blanks in CHAR values are always semantically insignificant. They are disregarded when you compare two CHAR values, not included in LENGTH calculations, and removed when you convert a CHAR value to another string type.
Trailing spaces in VARCHAR and CHAR values are treated as semantically insignificant when values are compared.
Length calculations return the length of VARCHAR character strings with trailing spaces included in the length. Trailing blanks are not counted in the length for fixed-length character strings.
