                              S H Q L  version 1.1

	Shql is a program that reads SQL commands interactively and
	executes those commands by creating and manipulating Unix files.

	This program requires a bourne shell that understands functions,
	as well as awk, grep, cut, sort, uniq, join, wc, and sed.

 	This script can be invoked with the command 

		shql [-q] {database name}

  	A directory must be created for the database before you may use it.
	This directory will house all data files for a single database.
	All datafiles are created with mode 666 ('rw-rw-rw-'), so create the
	directory with 777 ('rwxrwxrwx') if you want the database to be 
	sharable, and 700 ('rwx------') to be private.  Of course, multiple
	databases are possible.  A database called 'mydb' may be created
	as a directory $HOME/mydb, $HOME/shql/mydb, ./mydb, or as 
	$SHQL_ROOT/mydb, where $SHQL_ROOT is defined below.  The -q
	option turns off the display of headings so the output of shql
	can be used by other programs by caputuring all lines that begin
	the pipe symbol.

  	The program is patterned after Ingres' interactive sql terminal
	monitor program.  Terminal monitor commands begin with either a
	forward or back-slash.  Forward slashes may appear at the end of a
	commend line. Back-slashes are accepted for compatability.  The /g
	is the 'go' command, /p is print, and /q is quit.  Try 'help commands' 
	for a full list.  Because of this, if you need to put a slash as
	the second to last caracter on a line, you should add a space
	between the slash and the last character.
	
	To get started, invoke shql with a database name.  Use the directory 
	name you created above. Type

		shql mydb

	if the directory you created was 'mydb'.  Once shql starts up, you 
	should see the database name displayed, and then a '*'. At this
	point, the most valuable thing is to type help,

		* help
		* /g

	You may then go on.  The command 'help syntax' displays syntax
	for all SQL operations, and 'help commands' displays all shql
	workspace commands.  Try the demo.

	Shql can execute only one operation at a time, but operations can
	be spread over several lines.

	Shql operations are allow 'select' operations on multiple tables.
	Table names are read from left to write in select's 'from'
	section, so the tables should be ordered with the most central
	tables first.  In two-table joins, it doesn't matter.  In three
	table joins, if you join table A-to-B and B-to-C, B must not be
	the last table in the from clause, because shql will not be able
	to join tables A-C.  If you get the message 'Join not found, try
	reordering tables', this is probably the problem.  Also
	qualified field names are not understood, like tablename.fieldname,
	so if you are joining my_id in table A with my_id in table B, just
	say 'my_id = my_id'.  Views can also be used to create
	multi-table selects.

	Subselects are implemented, but must be the last operand of a
	'where' clause, most useful with 'in'.

	In most cases, commas are optional.  NULLs are not implemented.
	Aggregates like AVG() are implemented, but not with GROUP BY.

	When INSERTing strings that contain the characters !,=,>,<,(, or ),
	spaces or backslashes may be added during the insert.  This is a
	side-effect of the string manipulation needed to properly
	parse the command parameters.

	This SQL is type-less, so specify just the column width when creating
	tables.  This is used only for display purposes.  Shql is
	case-sensitive, and expects SQL key words to be in lower case.
	
	Commands can be piped into shql, and the table data files are
	tab delimited, so awk scripts can be used to generate reports 
	directly from the tables.  To operate on non-shql data files,
	create a dummy table with the proper fields, then copy your file
	into your shql data directory, replacing your delimiters with
	tabs, then run shql on the table, and convert the table back to 
	its original format.  Grave accents (`) may be used to execute 
	unix command from with shql.  Environment variables may also be
	used. See the demo for an example, i.e. "cat demo.shql | shql mydb".

	If you have comments, suggestions, or bug reports contact:

		Bruce Momjian, root@candle.uucp (root%candle.uucp@bts.com)
