column_info

$sth = $dbh->column_info( $catalog, $schema, $table, $column );

The statement handle returned has at least the following fields in the order shown below. Other fields, after these, may also be present.

TABLE_CAT: The catalog identifier. This field is NULL (undef) if not applicable to the data source, which is often the case. This field is empty if not applicable to the table.

TABLE_SCHEM: The schema identifier. This field is NULL (undef) if not applicable to the data source, and empty if not applicable to the table.

TABLE_NAME: The table identifier. Note: A driver may provide column metadata not only for base tables, but also for derived objects like SYNONYMS etc.

COLUMN_NAME: The column identifier.

DATA_TYPE: The concise data type code.

TYPE_NAME: A data source dependent data type name.

COLUMN_SIZE: The column size. This is the maximum length in characters for character data types, the number of digits or bits for numeric data types or the length in the representation of temporal types. See the relevant specifications for detailed information.

BUFFER_LENGTH: The length in bytes of transferred data.

DECIMAL_DIGITS: The total number of significant digits to the right of the decimal point.

NUM_PREC_RADIX: The radix for numeric precision. The value is 10 or 2 for numeric data types and NULL (undef) if not applicable.

NULLABLE: Indicates if a column can accept NULLs. The following values are defined:

  SQL_NO_NULLS          0
  SQL_NULLABLE          1
  SQL_NULLABLE_UNKNOWN  2

REMARKS: A description of the column.

COLUMN_DEF: The default value of the column, in a format that can be used directly in an SQL statement.

Note that this may be an expression and not simply the text used for the default value in the original CREATE TABLE statement. For example, given:

    col1 char(30) default current_user    -- a 'function'
    col2 char(30) default 'string'        -- a string literal
where "current_user" is the name of a function, the corresponding COLUMN_DEF values would be:

    Database        col1                     col2
    --------        ----                     ----
    Oracle:         current_user             'string'
    Postgres:       "current_user"()         'string'::text
    MS SQL:         (user_name())            ('string')

SQL_DATA_TYPE: The SQL data type.

SQL_DATETIME_SUB: The subtype code for datetime and interval data types.

CHAR_OCTET_LENGTH: The maximum length in bytes of a character or binary data type column.

ORDINAL_POSITION: The column sequence number (starting with 1).

IS_NULLABLE: Indicates if the column can accept NULLs. Possible values are: 'NO', 'YES' and ''.

SQL/CLI defines the following additional columns:

  CHAR_SET_CAT
  CHAR_SET_SCHEM
  CHAR_SET_NAME
  COLLATION_CAT
  COLLATION_SCHEM
  COLLATION_NAME
  UDT_CAT
  UDT_SCHEM
  UDT_NAME
  DOMAIN_CAT
  DOMAIN_SCHEM
  DOMAIN_NAME
  SCOPE_CAT
  SCOPE_SCHEM
  SCOPE_NAME
  MAX_CARDINALITY
  DTD_IDENTIFIER
  IS_SELF_REF

Drivers capable of supplying any of those values should do so in the corresponding column and supply undef values for the others.

Where is a list of translations for the codes appearing in some fields?

Based on my searching, they are not readily available. You probably need to go to an SQL forum and ask some experts where those can be found.