CS240A:A sample LDL Session

1
CS240AA sample LDL Session

• Carlo Zaniolo
• Department of Computer Science
• University of California, Los Angeles
• December, 2001

2
BSD UNIX

• whale 206 which ldl
• /u/class/cs249cz/ldl/LDL5.1
• whale 208 pwd
• /u/f3/zaniolo/recent/cs240a/example
• whale 209 ls
• city.fac city.prg
• whale 210 ldl
• 
  
• LDL System (Version 5.1)
  
• etc. ... rest of the banner
• ldl(1)gt
• ldl(1)gt open city.prg
• Opening file city.prg ... done.

3
OpenCompile Close

• ldl(2)gt compile
• Compiling all query forms in global module ...
• Error Free variables in head are not covered in
  the following unsafe rule
• 1 lcity_ff(C, Popl) lt- city_fbf(C, Texas,
  Pop), Pop gt_bb 400000.
• ldl(3)gt close
• Closing all modules ... done.
• HERE I EDIT THE PROGRAM
• ldl(4)gt open city.prg
• ldl(5)gt compile
• Compiling all query forms in global module ...
  done.

4
display and initdb

• ldl(6)gt display export
• Export in Module ldl_main_module
• export lcity(X, Y). compiled
• export lcity(X, Y). compiled
• ldl(7)gt initdb city.fac
• Initializing database from city.fac ... done.
• ldl(8)gt query lcity(X,Y)
• Querying lcity(X,Y) ...
• (Houston, 3000000)
• (Austin, 750000)
• (San Antonio, 1500000)
• The number of records is 3.

5
Command Completion

• ldl(1)gt e followed by space
• edit exit
• ldl(1)gt exit
• Exiting LDL ... Good Bye !!