/**
 *  call-seq:
 *  substitutions(variables,values,(precisions),(scales))
 *
 *  Defines an array of substitution variables.  The values may be strings,
 *  integers or decimals.  If they are decimals then the precisions and scales
 *  may also be specified. */
static VALUE sqlrcur_substitutions(int argc, VALUE *argv, VALUE self) {