Introduction to SQL
Which of the following query finds the name of the sailors who have reserved at least two boats?

SELECT DISTINCT s.sname FROM sailors s, reserves r1, reserves r2 WHERE s.sid = r1.sid AND r1.sid = r2.sid AND r1.bid ≠ r2.bid
SELECT DISTINCT s.sname FROM sailors s, reserves r1, reserves r2 WHERE s.sid = r1.sid AND r1.sid = r2.sid AND r1.bid <> r2.bid
SELECT DISTINCT s.sname FROM sailors s, reserves r1, reserves r2 WHERE s.sid = r1.sid AND COUNT(r1.bid) > r2.bid
All of these

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Introduction to SQL
Which of the following query is correct for using comparison operators in SQL?

SELECT name, course_name FROM student WHERE age>50 and WHERE age<80;
SELECT name, course_name FROM student WHERE age>50 and <80;
None of these
SELECT name, course_name FROM student WHERE age>50 and age <80;

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Introduction to SQL
The wildcard in a WHERE clause is useful when?

An exact match is not possible in a CREATE statement.
An exact match is necessary in a SELECT statement.
An exact match is not possible in a SELECT statement.
An exact match is necessary in a CREATE statement.

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Introduction to SQL
In an SQL SELECT statement querying a single table, according to the SQL-92 standard the asterisk (*) means that:

all records meeting the full criteria are to be returned.
None of these
all records with even partial criteria met are to be returned.
all columns of the table are to be returned.

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