0 votes 0 votes What does the following Tuple Relational Calculus query produce? The expression σθ1 (E1 ⋈θ2 E2) is the same as: E1 ⋈θ1^ θ2 E2 (σθ1 E1) ∧ (σθ2 E2 ) E1 ⋈ θ1∨ θ2 E2 None of the above Databases tbb-dbms-1 + – Bikram asked Nov 26, 2016 edited Jul 15, 2017 by Bikram Bikram 293 views answer comment Share Follow See 1 comment See all 1 1 comment reply KUSHAGRA गुप्ता commented Nov 10, 2019 reply Follow Share @Bikram sir, Is this right ? $\sigma _{\theta 1\wedge \theta 2}(E1\times E2)=(E1\Join_{\theta 1\wedge \theta 2}E2)=\sigma_{\theta 1}(E1\Join_{\theta 2}E2)=\sigma_{\theta 2}(E1\Join_{\theta 1}E2)$ 0 votes 0 votes Please log in or register to add a comment.
0 votes 0 votes What is the meaning of this line : σθ1(E1 ⋈θ2E2) ukn answered Jan 3, 2017 ukn comment Share Follow See 1 comment See all 1 1 comment reply Bikram commented Jan 4, 2017 reply Follow Share σ means selection , θ1 is condition 1 and θ2 is condition 2 . And E1 and E2 are two relations . Now , the theta-join ( E1 ⋈Condition E2) can be written as σCondition ( E1 Χ E2) Given expression is σθ1 (E1 ⋈θ2 E2) here we take the product of E1 and E2 now apply the condition θ1 * θ2 in the result . so , σθ1 (E1 ⋈θ2 E2) is the same as E1 ⋈θ1^ θ2 E2 . 1 votes 1 votes Please log in or register to add a comment.