Hercles Posted March 16, 2014 Report Share Posted March 16, 2014 Caros, como se faz um busca para obter a descrição de um material que nunca foi usado (em álgebra relacional)...? tenho a seguinte tabelas: CLIENTE(CPF, NOME_CLI) SAPATO (CODBARRA, NUMERO, MODELO, CPF) REPARO (CODBARRA, DATA_ULTIMO_CONSERTO, DATA_EXECUTADA) MATERIAL_REPARO(CODBARRA, DATA_EXECUTADA, CODMAT, QUANTIDADE) MATERIAL (CODMAT, DESCRICAO) Link to comment Share on other sites More sharing options...
Hercles Posted March 16, 2014 Author Report Share Posted March 16, 2014 Pensei nesta resposta: P(R1, Π descricao (σ descricao * MATERIAL) P(R2, Π descricao (σ descricao * MATERIAL_REPARO) R1 – R2 Link to comment Share on other sites More sharing options...
Guest user14912 Posted March 16, 2014 Report Share Posted March 16, 2014 Olá parece estar bem! Link to comment Share on other sites More sharing options...
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