E021-02, “CHARACTER VARYING data type (including all its spellings)”

1. Non-standard alternatives available
2. ⚡Empty strings become null
3. Very low implementation-defined limit: 1
4. Without the char varying synonym

The variable-length character string type of SQL is character varying but the shorter synonyms char varying and most importantly varchar are more commonly used.

CREATE TABLE … (
   email VARCHAR(320)
)

The varchar type can be parameterized to set a maximum length, like 320 in the example. Note that the unit are characters, not bytes.✓✗ In absence of the length attribute, the maximum length is implementation-defined (ID069), which is sometimes just a single character.

As the type varchar stores characters, rather than bytes, the character set and collate clauses may be specified.

Non-Standard Alternatives

Related

Supplementary Features

• T062, “Character length units”

Mandatory Features

• E021-01, “CHARACTER data type (including all its spellings)”

Optional Features

• F421, “National character”

• T046, “CLOB data type”

  • T043, “Multiplier T”

  • T044, “Multiplier P”

• T062, “Character length units”

• T081, “Optional string types maximum length”

Implementation-defined Elements

• ID069, “The implicit character maximum length when character maximum length is omitted.”

• IL042, “The maximum lengths for character string types and binary string types.”

Normative References

The SQL types character varying, char varying and char are defined in ISO/IEC 9075-2:2023 as mandatory feature E021-02, “CHARACTER VARYING data type (including all its spellings)”. They were already available in SQL-92 (entry level).