Zwischenstand

daten-abfragen/select-basic.sql

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+# use bookstore;
+
+select *
+from customers;
+
+select customers.firstname, customers.lastname, customers.age
+from customers;
+
+select count(*)
+from customers
+where customers.age > 30;
+
+select count(*)
+from customers
+where customers.age > 30
+  AND customers.age < 40;
+
+select *
+from customers
+where title = 'Frau Dr.'
+   OR title = 'Herr Dr.';
+
+select *
+from customers
+where (title = 'Frau Dr.' OR title = 'Herr Dr.')
+  AND age < 30;
+
+select count(distinct customers.lastname)
+from customers;
+
+select count(customers.age)
+from customers
+where age < 30;
+
+select distinct customers.firstname
+from customers;
+
+select distinct customers.firstname, lastname
+from customers;
+
+select count(distinct customers.firstname)
+from customers;
+
+# Aufgabe SELECT
+
+select count(*)
+from baby_names; # 220636
+
+select count(*)
+from baby_names
+where gender = 'm'; # 94322
+
+select `count`
+from baby_names
+where name = 'Alex'
+  and year = 2010
+  and gender = 'm';
+
+select count(distinct baby_names.name)
+from baby_names; # 6809
+
+select count(distinct baby_names.name)
+from baby_names
+where gender = 'm'; # 2756
+select count(distinct baby_names.name)
+from baby_names
+where gender = 'f'; # 4535
+
+select *
+from baby_names
+where `count` = 19250; # Sandra
+
+select *
+from baby_names
+where gender != 'm'
+  and gender != 'f';
+
+select distinct baby_names.gender
+from baby_names; # M, F
+
+select count(distinct baby_names.name, baby_names.gender)
+from baby_names;