lecture5 - Query Examples in Relational Algebra and SQL...

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Unformatted text preview: Query Examples in Relational Algebra and SQL Consider the relation schemas as follows. works(person name, company name, salary); lives(person name, street, city); located in(company name, city); managers(person name, manager name); where manager name refers to person name. a Find the names of the persons who work for company 'FBC' (company name='FBC'). Relational algebra: SQL: Select person_name From works Where company_name = 'FBC' b List the names of the persons who work for company 'FBC' along with the cities they live in. Relational algebra: SQL: Select lives.person_name, city From works, lives Where company_name = 'FBC' and works.person_name = lives.person_name c Find the persons who work for company 'FBC' with a salary of more than 10000. List the names of these persons along with the streets and cities where they live. Relational algebra: SQL: Select lives.person_name, stree, city From lives, works Where lives.person_name = works.person_name and salary > 10000 and works.company_name = 'FBC' @CDB1@@17 641$# 3$1$")$# $" HH G F E A'598 5 &% 2#% &!0 (' &% #! sv$ h g t g Q P gW d PI w HSYWXRXUXqTUU ' 2 % % % ! g g Q P S111$6b@11"(b&$# #$" P W d I SVUp' 5 @17 5 41$%# 23#$%1&$"a`XXUXUU H T 98 & !0 ( Y W R q T H q i h g f e XrpU 2 & ! dXc 'S@$y10 x$%# #$"aw sv$uXVURS QI sqrpU Xc h g t Y W R T P i h g f e d ! Y R T Q H G F E A 98 &% 2#%& 0 ( CDB' 5 @17 5 41$# 3$1$!"b&$%# #$"a`WXVURS PI 1 SV Q Vpq pXc VX 7SVUTp'S$%# #$"aw Y W T P d f q P 2 H & ! HWSpV P P d gV UpS@11%" 6( @%11"b$# $"aDWSV Q Vpq pXc VqX P Y e T ' 2% 5 2 % ( &% #! Y T P d f H Y W g SUX P P $' &3VUpDWSUeV P P d VUTp 4 T Y g H T 98 4&% 2#% !0 2 % Y W g SVUp' 5 @( 5 1$# 3$1&$"( @%11"auUX P P g Find the persons whose salaries are more than the salary of everybody who work for company 'SBC'. Relational algebra: XVUUU $UU VUpw Y W R T R q T 2 q T T H T ' SV UpS&$%# #$"aUU VUTp ! q T H T 98 4&% 2#%& 0 SVUp' 5 @17 5 1$# @@$1$!"(&$%# #$"`XRVUTUU ! Y W R q T f Find the names of the persons who do not work for company 'FBC'. Relational algebra: H e g Y Q VUVVUV P $'&$%# $!" !'aw # H ' 2y 42y ' ) ( e g Y Q U @$10 ! @@$10 !10131( ! 43131$ !'&a`VUVVUV P H h g % H S' &$XU P q Q $t S'D"$# $" ! 1&$%# @%$%V( # & P v H h g # ' &% #! 4 e Find the names of the persons who live in the same city and on the same street as their managers. Relational algebra: @' P VUpS@$10 @2@$1b$%# #$"aw HH h g q T g T f T ' 2y 4 y0 ( & ! H q rg P Xs$tDVUpS@$y10 x&$%# #$"s P VUp T v T ' 2 ! q T g T f T d Find the names of the persons who live and work in the same city. Relational algebra: SQL: SQL: SQL: Select person_name From works Where person_name not in (Select person_name From works Where company_name = 'FBC') Select e.person_name From lives e, lives m, managers Where e.person_name = managers.person_name and m.person_name = managers.manager_name and e.street = m.street and e.city = m.city Select person_name From works, lives, locates_in Where works.person_name = lives.person_name and works.company_name = located_in.company_name and located_in.city = lives.city 2 VXV rg P X w g g Y Y W q T rg P X' 5 @( 5 41$# 23$%1&$"( 2@$1VXV H q T 98 &% # !0 y0 g g Y Y W Relational algebra (another solution): H e ' &% 2#%&!0 pX c V P UT I S$# 3$1$" 27rg P XS&$%# 23#$1&$"aw H q T ' % !0 rg P X 2 S P &VUV q pQ UV qr Q i DpX c V P UT I q T q T g T f Y W e P T Y g P e VXV H )S$# 3$1$"a S P VVYSXX eVq pQ UV r Q i g g Y Y W C' &% 2#%&!0 q T g T f W P T Y q g P rg P X' 5 @( 5 41$# 23$%1&$"( 2@$1VXV H q T 98 &% # !0 y0 g g Y Y W Relational algebra: h Find the names of the companies that is located in every city where company 'SBC' is located in. SQL (another solution): SQL: SQL: Select company_name From located_in t Where not exists (Select * From located_in s Select company_name From located_in t Where (Select city From located_in s Where t.company_name = s.company_name) contains (Select city From located_in s1 Where s1.company_name = 'SBC') Select person_name From works Where salary > all (Select salary From works Where company_name = 'SBC') Where s.company_name = 'SBC' and s.city not in (Select city From located_in l Where l.company_name = t.company_name)) 3 ...
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