#
# Database specific definitions for a XBase module
#

# This function generates a mapping of ANSI type names to
# database specific type names; it is called by TableDefinition().
sub AnsiTypeToDb ($;$) {
	my ($type, $size) = @_;
	my ($ret);

	if ((lc $type) eq 'blob') { $ret = 'memo'; }
	elsif ((lc $type) eq 'int'  ||  (lc $type) eq 'integer')
		{ $ret = $type; }
	elsif ((lc $type) eq 'char') { $ret = "CHAR($size)"; }
	else { warn "Unknown type $type\n"; $ret = $type; }
	$ret;
	}


#
#   This function generates a table definition based on an
#   input list. The input list consists of references, each
#   reference referring to a single column. The column
#   reference consists of column name, type, size and a bitmask of
#   certain flags, namely
#
#       $COL_NULLABLE - true, if this column may contain NULL's
#       $COL_KEY - true, if this column is part of the table's
#           primary key
#
#   Hopefully there's no big need for you to modify this function,
#   if your database conforms to ANSI specifications.
#

sub TableDefinition ($@) {
    my($tablename, @cols) = @_;
    my($def);

    #
    #   Should be acceptable for most ANSI conformant databases;
    #
    #   msql 1 uses a non-ANSI definition of the primary key: A
    #   column definition has the attribute "PRIMARY KEY". On
    #   the other hand, msql 2 uses the ANSI fashion ...
    #
    my($col, @keys, @colDefs, $keyDef);

    #
    #   Count number of keys
    #
    @keys = ();
    foreach $col (@cols) {
	if ($$col[2] & $::COL_KEY) {
	    push(@keys, $$col[0]);
	}
    }

    foreach $col (@cols) {
	my $colDef = $$col[0] . " " . AnsiTypeToDb($$col[1], $$col[2]);
#	if (!($$col[3] & $::COL_NULLABLE)) {
#	    $colDef .= " NOT NULL";
#	}
	$$col[3] |= $::COL_NULLABLE;
	push(@colDefs, $colDef);
    }
    if (@keys) {
	$keyDef = ", PRIMARY KEY (" . join(", ", @keys) . ")";
    } else {
	$keyDef = "";
    }
    $def = sprintf("CREATE TABLE %s (%s%s)", $tablename,
		   join(", ", @colDefs), $keyDef);
}

### DBI->trace(2);

#
#   This function generates a list of tables associated to a
#   given DSN.
#
sub ListTables(@) {
    my($dbh) = shift;
    my(@tables);

    @tables = $dbh->func('_ListTables');
    if ($dbh->errstr) {
	die "Cannot create table list: " . $dbh->errstr;
    }
    @tables;
}


#
#   Return a string for checking, whether a given column is NULL.
#
sub IsNull($) {
    my($var) = @_;

    "$var IS NULL";
}


#
#   Return TRUE, if database supports transactions
#
sub HaveTransactions () {
    0;
}


1;