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KEY

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The >KEY command specifies the location of the key data items in a file's records which are to be sorted or merged.

SYNTAX


  >K[EY] keyspec1 [; keyspec2]...[; keyspecN]

PARAMETERS

keyspec

A group of parameters used to specify a key data item to be sorted or merged. The syntax of the keyspec parameters follows: 


   position, length [,type][,DESC]

position

A positive number (integer) specifying the position of the first character of the key data item within the record. (The first position of a record line is numbered one.)

length

A positive number (integer) indicating the length of the data item key field in bytes.

type

Defines the type of data contained in the data item key field. The type of data can be one of the following:

B[YTE]

A direct byte comparison is used. It is the default value for the type parameter and should be used for ASCII or EBCDIC data. The specification of an alternate collating sequence via the >DATA and >ALTSEQ commands affects the collating of this key type only.

C[HARACTER]

The collating sequence for the native language defined in the >LANGUAGE command is used. If no >LANGUAGE command has been issued, SORT/XL and MERGE/XL use the default data language of the system (usually ASCII). Refer to the Native Language Programmer's Guide for additional information on the default data language.

I[NTEGER]

The key data item field contains a two's complement number of the specified length in bytes. Any value may be specified for length. The length parameter defaults to two bytes.

R[EAL]

The key data item field contains a floating-point number in standard HP 3000 format. Any value may be entered for length. The length parameter defaults to four bytes.

L[ONG]

LONG is the same as REAL except that length defaults to eight bytes.

F[POINT]

The key data item field contains a floating-point number in IEEE standard format. The length parameter defaults to four bytes. Any value may be entered for length.

NOTE: NANs (Not A Number) will collate at the beginning or end for IEEE floating-point numbers. The method of reporting (or ignoring) these entities has not been determined.

F8[POINT]

Same as FPOINT except that length defaults to eight bytes.

F16[POINT]

Same as FPOINT except that length defaults to sixteen bytes.

T[WO-BYTE]

Key data item field contains 16-bit data. The length specified for this key type must be an even number of bytes.

P[ACKED]

Key data item field contains a packed decimal number. In this format, each character except the last contains two digits. Each digit occupies four bits. The rightmost character contains the least significant digit of the number in its four leftmost bits, and the sign of the number in its four rightmost bits. The sign is considered minus if it has the value 1101 (binary) and plus otherwise.

PACKED*

Same as PACKED except there are an even number of digits and a sign. The leftmost four bits are not treated as part of the field.

DI[SPLAY-TRAILING-SIGN]

Key field contains a numeric display quantity. Numeric display items are represented by ASCII-coded decimal digits (0 through 9) except for the rightmost digit, which carries the sign of the data item. The sign is determined according to the table shown in Figure 6-1. (Sign is optional.) For example, 123 is represented by 12C.

DISPLAY-L[EADING-SIGN]

In this case, the leftmost digit carries the sign of the data item. For example, -123 is represented by J23. Refer to the table shown in Figure 6-1. (Sign is optional.)

DISPLAY-TRAILING-SIGN-S[EPARATE]

The sign is contained in the character position to the right of the rightmost digit. For example, 123 is represented by 123+. (Sign can be blank.)

DISPLAY-LEADING-SIGN-S[EPARATE]

The sign is contained in the character position to the left of the leftmost digit. For example, -123 is represented by -123. (Sign can be blank.)

DESC

Indicates the records are to be arranged in descending order. If this parameter is not specified, the records are arranged in the default ascending order.


  Display    Positive      Negative      No Sign
   Digit

     0       { (%173 $78)  } (%175 $7D)  0 (%60 $30)
     1       A (%101 $41)  J (%112 $4A)  1 (%61 $31)
     2       B (%102 $42)  K (%113 $4B)  2 (%62 $32)
     3       C (%103 $43)  L (%114 $4C)  3 (%63 $33)
     4       D (%104 $44)  M (%115 $4D)  4 (%64 $34)
     5       E (%105 $45)  N (%116 $4E)  5 (%65 $35)
     6       F (%106 $46)  O (%117 $4F)  6 (%66 $36)
     7       G (%107 $47)  P (%120 $50)  7 (%67 $37)
     8       H (%110 $48)  Q (%121 $51)  8 (%70 $38)
     9       I (%111 $49)  R (%122 $52)  9 (%71 $39)

DISCUSSION

SORT-MERGE/XL sorts keys contain binary, ASCII, or EBCDIC data according to an eight-bit binary sequence (00000000 to 11111111), except for the type CHARACTER, which is sorted according to the collating sequence of the native language specified in the >LANGUAGE command. Refer to Appendix C for further information on native language collating. Other types of data (integer, real, etc.) are sorted according to the standard arithmetic relational operators. For example, 2 is greater than -5. The keys can contain alphabetic, numeric, or alphanumeric (alphabetic and numeric intermixed) data. They can be contiguous or separated in a record or they can overlap each other, provided the collating sequence is not altered, or a user-defined sequence is not used. An entire record can be considered as a single key.

As explained in Chapter 3, each >KEY command can specify one or more key fields which are separated by semicolons. Multiple key fields can also be specified with more than one >KEY command. All the key fields do not have to be specified in the same command. The most significant key is called the major key and is declared first in the command. Other keys have decreasing significance according to their relative positions following the major key. They are compared if a comparison or more significant keys results in an equal condition.

Consider a file containing the records of all the students in a high school. Each record can contain information such as name, address, grade level, grades in individual courses, as well as data on other information. You can specify the order in which the records are sorted. If the first record is of the student with the highest grades (A) in English and Math, you specify an ascending order. If the major key is English and the other key is Math, the data in the Math fields are compared only if the data in the English fields are the same. The sorting order is specified in the same commands that specify the keys. An order is declared for each key. This order does not have to be the same for all the keys in a record. For example, in the high school file, you can declare English (major key) with an ascending order and Math with a descending order. Note even if the sorting order is different for each key, only one collating sequence is used for a particular operation.

EXAMPLES

The following examples show using the >KEY command and some of its options: 

  >KEY 10, 5
BYTE key of length 5 starting in position 10, sorted in the ascending order. 

  >KEY 20, REAL
REAL key of length 4, starting in position 20 and sorted in an ascending order since four is the default for the length parameter when the key data type is REAL. 

  >KEY 30, 20, INT, DESC
20-byte integer key starting in position 30, and sorted in a descending order.

For information on making corrections to the key specification, refer to the >RESET command in this chapter.

ADDITIONAL DISCUSSION

Refer to the >RESET command in this chapter.



INPUT (SORT/XL)

LANGUAGE