# Basics of Sets and Relations #5

# Basics of Sets and Relations #5

tibi01993 + 0 comments http://www.mathsisfun.com/algebra/sigma-notation.html This link explains clearly what is that symbol. FYI

aashray18521 + 0 comments Mysql equivalent:

`Select count(*) from student where number<3000;`

shahnawaz_jrw + 0 comments Answer is: 2

Syntax: σp(r)

Where, σ represents the Select Predicate, r is the name of relation(table name in which you want to look for data), and p is the prepositional logic, where we specify the conditions that must be satisfied by the data. In prepositional logic, one can use unary and binary operators like =, <, > etc, to specify the conditions.

shoeb5436 + 0 comments It must return 2. so the answer is 2

jacobdickey_2016 + 3 comments I dont understand what this is asking

manuelj + 0 comments This might help:

σ condition(relation): condition is a boolean expression in which rows are selected for which the condition is true

Source: http://jcsites.juniata.edu/faculty/rhodes/dbms/relalg.htm

brandon_loza15 + 1 comment rows are going vertically since they are asking for the number >3000 and the student name it should give you 2 rows

manuelj + 0 comments The condition is number < 3000, just in case someone gets confused.

LSRahul + 0 comments What is the count of rows returned in the following relational selection? ans =2

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