IBM 000-8697 Manual de usuario descargar pdf (Pagina 499)

100

101

Utilities 7-21

How to Create a Command File

Beforeyouuse dbload,youﬁrstcreateanASCIIcommand ﬁle thatnamesthe

input data ﬁles and the tables that receive the data. The command ﬁle maps

ﬁelds from one or moreinput ﬁles intocolumns ofone ormoretables within

your database.

The command ﬁle contains only FILE and INSERT statements. Each FILE

statement names an input data ﬁle. The FILE statement also deﬁnes the data

ﬁelds from the input ﬁle that will be inserted into the table. Each INSERT

statementnames a table thatwillreceivethedata.TheINSERT statementalso

deﬁnes how dbload will place the data described in the FILE statement into

the columns of the table.

Within thecommandﬁle,theFILE statementcanappearinthe following two

forms:

■ Delimiter form

■ Character-position form

Use the delimiter form of the FILE statement when every ﬁeld in the input

data row uses the same delimiter and every row ends with a NEWLINE

character. This formatis typical of datarowswith variable-length ﬁelds. You

can alsouse thedelimiter formof theFILE statement withﬁxed-length ﬁelds

as long asthe datarowsmeet the delimiterand NEWLINE requirements. The

delimiterform of FILEandINSERT iseasiertouse than thecharacter-position

form.

Use the character-position form of the FILE statement when you cannot rely

on delimiters and you need to identify the input data ﬁelds by character

position within the input row. For example, you would use this form to

indicate that the ﬁrst input data ﬁeld begins at character position 1 and

continues until character position 20.

Another reason to use this second form is if you must translate a character

stringintothenullvalue. For example, if yourinputdataﬁleusesasequence

of blanks to indicate a null value, you must use the second form if you want

to instruct dbload to substitute null at every occurrence of the blank-

character string.

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