“”UNION”” COMPATIBILITY (u.c.) of TWO RELATIONS For a binary expression, the two participating relations (operands — R1 and R2) must have the following structural constraints for the expression to be type correct: 1) both relations have the same degree (i.e. n); & 2) for each attribute (1 < = i <= n), the domain (R1.Attr_i) = domain(R2.Attr_i).
“”UNION”” UPATANIFU (uc) ya RELATIONS PILI Kwa usemi binary, wawili wanaoshiriki mahusiano (operands – R1 na R2) lazima kuwa na yafuatayo vikwazo kimuundo kwa ajili ya kujieleza kuwa na aina sahihi: 1) Mahusiano wote wana shahada hiyo (yaani n); & 2) kwa kila sifa (1 <= i <= n), uwanja (R1.Attr_i) = domain (R2.Attr_i).