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Meaning (Semantics) of SQL Queries
SELECT a1, a2, …, ak
FROM R1 AS x1, R2 AS x2, …, Rn AS xn
WHERE Conditions
1. Nested loops:
Answer =
{}
for
x1 in R1 do
for x2 in R2 do
…..
for xn in Rn do
if
Conditions
then
Answer = Answer È
{(a1,…,ak)}
return
Answer