Binary strings

Fixed-length binary strings

The type of fixed-length binary strings is BINARY. When fixed-length binary string distinct types, columns, and variables are defined, the length attribute is specified, and all values have the same length. For a fixed-length binary string, the length attribute must in the range 1–255 inclusive.

Varying-length binary strings

The types of varying-length binary strings are VARBINARY (BINARY VARYING) and BLOB (BINARY LARGE OBJECT)

When varying-length binary strings, distinct types, columns, and variables are defined, the maximum length is specified and this length becomes the length attribute. Actual length values might have a smaller value than the length attribute value. For varying-length binary strings, the actual length specifies the number of bytes in the string.

For a VARBINARY string, the length attribute must in the range 1–32704. For a VARBINARY string column, the maximum for the length attribute is determined by the record size that is associated with the table, as described in "Maximum record size" on the description of the CREATE TABLE statement. Like a varying-length character string, varying-length binary string could be an empty string.

A binary string column is useful for storing non-character data, such as encoded or compressed data, pictures, voice, and mixed media. Another use is to hold structured data for exploitation by distinct types, user-defined functions, and stored procedures. Note, that although binary strings and FOR BIT DATA character strings might be used for similar purposes, the two data types are not compatible. The BINARY, BLOB, VARBINARY built-in functions and CAST specification can be used to change a FOR BIT DATA character string into a binary string.