GATE 1999 CSE & IT PYQ

Question

The relational algebra expression equivalent to the following tuple calculus expression:

$$\left\{ {t|t \in r \wedge \left( {t\left[ A \right] = 10 \wedge t\left[ B \right] = 20} \right)} \right\}$$ is:

Accepted Answer

$${\sigma _{\left( {A = 10} \right)}}\left( r \right) \cap {\sigma _{\left( {B = 20} \right)}}\left( r \right)$$

Answer

$${\sigma _{\left( {A = 10 \vee B = 20} \right)}}\left( r \right)$$

Answer

$${\sigma _{\left( {A = 10} \right)}}\left( r \right) \cup {\sigma _{\left( {B = 20} \right)}}\left( r \right)$$

Answer

$${\sigma _{\left( {A = 10} \right)}}\left( r \right) - {\sigma _{\left( {B = 20} \right)}}\left( r \right)$$