BQL version 1.0

Legal Status
BQL is freeware. Copying is  allowed,  commercial  use  is  not.  Unlike  many
others,  I  do  not  demand  that all file must be left together unchanged, on
three conditions:
1. The same rules about use apply.
2. This declaration about the legal status must stay along with the files.
3. It must be made clear that something has been changed or left out.
If it is a substantial improvement of the program, I wish to receive a copy.

© 1992: Reinhard Pflüger
        Hermannstr. 3
        D-60318 Frankfurt
        Germany

What is BQL?
BQL stands for "bBase Query Language". This is to say:
1. BQL is a database query language; it is not only its name that resembles to
   SQL.
2. The data format is compatible with bBaseII (from Fish #563).  But  BQL  can
   also be used without bBaseII.

Usage
Start: from workbench or CLI without parameters.
A window is opened, in which the query is entered, e. g.:

from xy.bbase
select column1 column2
where column3 < string
sums
to "My output file"
create yz.bbase
end

Explication:
from: file(s)  to  be  read  from.  The  first one must be a database in bBase
      format. All others are supposed to be in bBase format if their name ends
      in .bbase, otherwise humanly readable format (see "FurtherDoc").  Unlike
      SQL, BQL does not evaluate a cartesian product (join), but the files are
      treated  like  one  big file. They must have the same number of columns,
      and the order of the columns must be the same too.
select: names of the columns to be selected. If a column name contains spaces,
        only the part in front of them is to be written. Strings that are  not
        names  of  columns  are  interpreted as constants. # numbers the lines
        that are written. By * all columns are selected.
where: conditions  of  the form "column-name operator constant". The spaces in
       front of and after the operator are necessary.  If  several  conditions
       are  given,  all  of them must be true. If you use the keyword "unless"
       instead of "where", all conditions must be false. Valid operators are:
       > < = <= >= <>   string comparison
       +                Is the constant contained as a substring?
       -                Is the constant not contained as a substring?
       l                numerically less than
       g                numerically greater than
sums: At  the  end  a  sum  line  is  written (for all columns only containing
      integers, their sum; for all others "SUM").
end: end of query. Entering CTRL-\ has the same effect.
to: file  to  which the output is to be sent. Default is "T:tempA" if "create"
    is given (in further passes "T:tempB" etc. - see "FurtherDoc" under "go").
    Otherwise a "CON:" window is the default.
    If "create" is not given, a title line  containing  the  column  names  is
    generated.
create: Create the named database of the output data.

The keywords may be entered in any  order.  They  must  be  written  in  small
letters.  Also apart from that BQL is always case sensitive. "to" and "create"
can be followed by one parameter,  "sums"  (and  "nosums",  cf.  "FurtherDoc")
none,  all other keywords up to 9. (in the case of "where": 9 complete compar-
isons)
Expressions can be divided (without difference in meaning) by any number of:
- spaces
- linefeeds
- commas
Combinations of them are allowed too.
Expressions containing one of these characters  must  be  enclosed  in  double
quotes  ("), equally such ones that are identical with keywords. After such an
expression no division character is necessary (but it is allowed).
Double quotes in expressions are not allowed. Single quotes (') are ok.

For the keywords "go", "run" and "nosums" see "FurtherDoc".

NB: The syntax check is not complete. The valid  principle  is:  "garbage  in,
garbage out". In some circumstances the program will quit with an error messa-
ge (e. g. when there are too many parameters); but thanks to the Modula2  run-
time  system  this does not cause a guru. If it does, or if you do not get the
desired output although the query is correct, let me know it!