Question
Q1. A database consists of four tables T1, T2, T3 & T4. Underlined columns represent primary key relation in respective tables. Foreign key constraints are
Q1. A database consists of four tables T1, T2, T3 & T4. Underlined columns represent primary key relation in respective tables. Foreign key constraints are as shown with arrows. Text on arrows represent the reference relation. That is foreign key (a, b) in T2 references T1(a, b). Like-wise the other arrows need to be interpreted. What is the correct order of creating tables?
1. t1, t2, t3, t4
2. t1, t3, t4, t2
3. t1, t3, t2, t4
4. t4, t3, t2, t1
Q2. A database consists of four tables T1, T2, T3 & T4. Underlined columns represent primary key relation in respective tables. Foreign key constraints are as shown with arrows. Text on arrows represent the reference relation. That is foreign key (a, b) in T2 references T1(a, b). Like-wise the other arrows need to be interpreted. Given this constraint relation among tables, how do you drop primary key constraint on T1? You must identify only those statements which exactly achieve this task. Those statements which achieve more than required will not be considered as correct answer
1. 1) drop foreign key constraint between T2 and T4 (2) drop foreign key constraint between T2 and T1 (3) drop foreign key constraint between T4 and T1 (4) drop foreign key constraint between T3 and T1 (5) drop primary key constraint on T1
2. (1) drop foreign key constraint between T2 and T1 (2) drop foreign key constraint between T4 and T1 (3) drop foreign key constraint between T3 and T1 (4) drop primary key constraint on T1
3. (1) drop foreign key constraint between T2 and T4 (2) drop foreign key constraint between T2 and T3 (3) drop foreign key constraint between T4 and T1 (4) drop foreign key constraint between T3 and T1 (5) drop primary key constraint on T1
4. (1) drop foreign key constraint between T3 and T1 (2) drop foreign key constraint between T4 and T1 (3) drop foreign key constraint between T2 and T1 (4) drop primary key constraint on T1
Ti(a, b, c) (a, b) (a, b) (a, b) T2(a, d, b) T3(a, e, b) (a, b) (a, b) T4(a, b, f) aStep by Step Solution
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