25 lines
1.2 KiB
MySQL
25 lines
1.2 KiB
MySQL
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INSERT INTO PROFESOR(cod_pro, nombre) VALUES('JR', 'Juan Ruiz');
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-- Fails here, constraint is INITIALLY IMMEDIATE
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INSERT INTO PROFESOR(cod_pro, nombre) VALUES('JR', 'Javier Pérez');
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ROLLBACK; -- Don't save the first insertion
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-- Change constraint to be INITIALLY DEFERRED
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ALTER TABLE profesor DROP PRIMARY KEY CASCADE KEEP INDEX;
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ALTER TABLE profesor ADD CONSTRAINT cp_prof PRIMARY KEY(cod_pro) INITIALLY DEFERRED DEFERRABLE;
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-- Because we used CASCADE to DROP the primary key constraint,
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-- we need to restore the FOREIGN KEY in docencia
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ALTER TABLE docencia
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ADD CONSTRAINT ca_doc_prof
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FOREIGN KEY(cod_pro) REFERENCES profesor(cod_pro) INITIALLY IMMEDIATE DEFERRABLE;
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INSERT INTO PROFESOR(cod_pro, nombre) VALUES('JR', 'Juan Ruiz');
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INSERT INTO PROFESOR(cod_pro, nombre) VALUES('JR', 'Javier Pérez');
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-- Fails here, constraint is INITIALLY DEFERRED
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COMMIT;
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-- Restore constraint to initial setting
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ALTER TABLE profesor DROP PRIMARY KEY CASCADE KEEP INDEX;
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ALTER TABLE profesor ADD CONSTRAINT cp_prof PRIMARY KEY(cod_pro) INITIALLY IMMEDIATE DEFERRABLE;
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ALTER TABLE docencia ADD CONSTRAINT ca_doc_prof FOREIGN KEY(cod_pro) REFERENCES profesor(cod_pro) INITIALLY IMMEDIATE DEFERRABLE;
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