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READ

Description

The READ statement allows a program to read a record from a previously opened file into a variable. It takes the general form:

READ variable1 FROM { variable2,} expression {SETTING setvar} {ON ERROR statements} {THEN|ELSE statements}

Where:

  • variable1 is the identifier into which the record will be read.
  • variable2, if specified, should be a file variable that has previously been opened to a file using the OPEN statement. If variable2 is not specified then the default file variable is assumed.
  • The expression should evaluate to a valid record key for the file.
  • If the SETTING clause is specified and the read fails, setvar will be set to one of these values
  • If ON ERROR is specified, the statements following the ON ERROR clause will be executed for any of the above Incremental File Errors except error 128.
  • If the READ is successful then the statements following THEN will be executed. If the READ is unsuccessful, i.e. the record key does not exist in the file, then the statements following ELSE are executed. If the READ is unsuccessful and there is no ELSE then expression is set to "" (null).

If a lock is to be set on a record, it should be explicitly stated with the READU statement.

An example of use is as: 

0001     $option jabba
0002
0003     open "dummy_records" to file_variable else abort 201, "dummy_records"
0004     read rec_variable from file_variable, 7 setting error_variable on error
0005         crt error_variable
0006     end then
0007         for rec_index = 1 to dcount(rec_variable, @AM)
0008             crt rec_variable<rec_index>
0009         next rec_index
0010     end

to show all the contents of record 7 to the terminal. Note that this code is JabbaScript.

Go back to jBASE BASIC.

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