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133 lines
4.8 KiB
Text
133 lines
4.8 KiB
Text
drop table if exists t1,t2,t3;
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create table t1 (libname varchar(21) not null, city text, primary key (libname));
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create table t2 (isbn varchar(21) not null, author text, title text, primary key (isbn));
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create table t3 (isbn varchar(21) not null, libname varchar(21) not null, quantity int ,primary key (isbn,libname));
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insert into t2 values ('001','Daffy','A duck''s life');
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insert into t2 values ('002','Bugs','A rabbit\'s life');
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insert into t2 values ('003','Cowboy','Life on the range');
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insert into t2 values ('000','Anonymous','Wanna buy this book?');
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insert into t2 values ('004','Best Seller','One Heckuva book');
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insert into t2 values ('005','EveryoneBuys','This very book');
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insert into t2 values ('006','San Fran','It is a san fran lifestyle');
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insert into t2 values ('007','BerkAuthor','Cool.Berkley.the.book');
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insert into t3 values('000','New York Public Libra','1');
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insert into t3 values('001','New York Public Libra','2');
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insert into t3 values('002','New York Public Libra','3');
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insert into t3 values('003','New York Public Libra','4');
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insert into t3 values('004','New York Public Libra','5');
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insert into t3 values('005','New York Public Libra','6');
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insert into t3 values('006','San Fransisco Public','5');
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insert into t3 values('007','Berkeley Public1','3');
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insert into t3 values('007','Berkeley Public2','3');
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insert into t3 values('001','NYC Lib','8');
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insert into t1 values ('New York Public Libra','New York');
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insert into t1 values ('San Fransisco Public','San Fran');
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insert into t1 values ('Berkeley Public1','Berkeley');
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insert into t1 values ('Berkeley Public2','Berkeley');
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insert into t1 values ('NYC Lib','New York');
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select t2.isbn,city,t1.libname,count(t1.libname) as a from t3 left join t1 on t3.libname=t1.libname left join t2 on t3.isbn=t2.isbn group by city,t1.libname;
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isbn city libname a
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007 Berkeley Berkeley Public1 1
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007 Berkeley Berkeley Public2 1
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000 New York New York Public Libra 6
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001 New York NYC Lib 1
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006 San Fran San Fransisco Public 1
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select t2.isbn,city,t1.libname,count(distinct t1.libname) as a from t3 left join t1 on t3.libname=t1.libname left join t2 on t3.isbn=t2.isbn group by city having count(distinct t1.libname) > 1;
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isbn city libname a
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007 Berkeley Berkeley Public1 2
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000 New York New York Public Libra 2
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select t2.isbn,city,t1.libname,count(distinct t1.libname) as a from t3 left join t1 on t3.libname=t1.libname left join t2 on t3.isbn=t2.isbn group by city having count(distinct concat(t1.libname,'a')) > 1;
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isbn city libname a
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007 Berkeley Berkeley Public1 2
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000 New York New York Public Libra 2
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select t2.isbn,city,@bar:=t1.libname,count(distinct t1.libname) as a
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from t3 left join t1 on t3.libname=t1.libname left join t2
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on t3.isbn=t2.isbn group by city having count(distinct
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t1.libname) > 1;
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isbn city @bar:=t1.libname a
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007 Berkeley Berkeley Public1 2
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000 New York New York Public Libra 2
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SELECT @bar;
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@bar
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Berkeley Public2
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select t2.isbn,city,concat(@bar:=t1.libname),count(distinct t1.libname) as a
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from t3 left join t1 on t3.libname=t1.libname left join t2
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on t3.isbn=t2.isbn group by city having count(distinct
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t1.libname) > 1;
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isbn city concat(@bar:=t1.libname) a
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007 Berkeley Berkeley Public1 2
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000 New York New York Public Libra 2
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SELECT @bar;
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@bar
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Berkeley Public2
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drop table t1, t2, t3;
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create table t1 (f1 int);
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insert into t1 values (1);
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create table t2 (f1 int,f2 int);
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select t1.f1,count(distinct t2.f2),count(distinct 1,NULL) from t1 left join t2 on t1.f1=t2.f1 group by t1.f1;
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f1 count(distinct t2.f2) count(distinct 1,NULL)
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1 0 0
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drop table t1,t2;
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create table t1 (f int);
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select count(distinct f) from t1;
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count(distinct f)
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0
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drop table t1;
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create table t1 (a char(3), b char(20), primary key (a, b));
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insert into t1 values ('ABW', 'Dutch'), ('ABW', 'English');
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select count(distinct a) from t1 group by b;
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count(distinct a)
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1
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1
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drop table t1;
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create table t1 (f1 int, f2 int);
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insert into t1 values (0,1),(1,2);
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select count(distinct if(f1,3,f2)) from t1;
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count(distinct if(f1,3,f2))
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2
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drop table t1;
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create table t1 (i int);
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insert into t1 values (0), (1);
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create view v1 as select * from t1;
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select count(distinct i) from v1;
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count(distinct i)
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2
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drop table t1;
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drop view v1;
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create table t1 (user_id char(64) character set utf8);
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insert t1 values(1),(2),(3),(4),(5),(6),(7),(8),(9),(10),(11),(12),(13),(14),(15),(16),(17);
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set @@tmp_table_size = 1024;
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select count(distinct user_id) from t1;
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count(distinct user_id)
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17
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alter table t1 modify user_id char(128) character set utf8;
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select count(distinct user_id) from t1;
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count(distinct user_id)
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17
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drop table t1;
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set @@tmp_table_size = default;
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create table t1 (
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a VARCHAR(1020),
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b int
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);
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insert into t1 values
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( 0 , 1 ),
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( 1 , 2 ),
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( 2 , 3 ),
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( 3 , 4 ),
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( 4 , 5 ),
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( 5 , 6 ),
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( 6 , 7 ),
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( 7 , 8 ),
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( 8 , 9 ),
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( 9 , 10 ),
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( 0 , 11 ),
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( 1 , 12 ),
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( 2 , 13 ),
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( 3 , 14 );
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set @@tmp_table_size=1024;
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select count(distinct a) from t1;
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count(distinct a)
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10
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drop table t1;
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set @@tmp_table_size = default;
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