if 0 {Richard Suchenwirth 2004-03-22 - In A simple database, I showed how databases may be implemented with Tcl arrays. This take here is closer to traditional relational databases, with tables of pre-defined columns (modeled here as a list of lists, the first being the column heading, the rest the "records"), and mimicks the SQL SELECT statement a bit:}
proc select {fields "from" tbl "where" condition} { set infields [lindex $tbl 0] if {$fields eq "*"} {set fields $infields} set res [list $fields] foreach inrow [lrange $tbl 1 end] { foreach $infields $inrow break if $condition { set row {} foreach field $fields {lappend row [set $field]} lappend res $row } } set res
} #-- Test data:
set table { {number description pieces} {1234 Foo 100} {2345 Bar 50} {3456 Grill 2} }
if 0 {#-- Testing:
% select * from $table where {$pieces < 100} {number description pieces} {2345 Bar 50} {3456 Grill 2} % select {pieces description} from $table where {$number != 1234} {pieces description} {50 Bar} {2 Grill}
Cute, ain't it? There is a danger though, if you happen to name a "database" column condition, row, fields, res or so... because the column names are used as variables, and could override the working variables.