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Mysql 19 19 20 constraints over multiple tables

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Unformatted text preview: straints Over Multiple Tables Suppose the number of sailors plus the number of boats should be less than 100. This will not work: not CREATE TABLE Sailors ( sid INTEGER, sname CHAR(10), rating INTEGER, age REAL, PRIMARY KEY (sid), (sid), CHECK ((SELECT COUNT (S.sid) (S.sid) FROM Sailors S) + (SELECT COUNT(B.bid) FROM BOATS B) COUNT(B.bid) < 100)); Assertion CREATE ASSERTION SmallClub CHECK ((SELECT COUNT (S.sid) FROM Sailors S) (S.sid) + (SELECT COUNT (B.bid) FROM Boats B) (B.bid) < 100); Not supported by MySQL. MySQL. 21 Exercise 5.10.2 (p. 180) 22 Enforcing Integrity Constraints What happens if we: Consider the following relational schema. Emp (eid, ename, age, salary) Works (eid, did, pct_time) Dept (did, budget, managerid) • Try to insert tuple with same PK as another tuple in table? • Try to insert tuple with null PK? • Try to insert tuple with value for field that’s not in domain (type) for that field? • Try to modify tuple’s PK so that new PK value is same as another in table? Write...
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