具有標准名人的訪問計數記錄數

Question

我一直在尋找解決問題的方法，希望您能幫到我，我有一張桌子，上面有兩列，一個是名字，兩個是一個城鎮，我需要從埃皮特計算莎拉的次數，但是重復的次數是技巧我需要下面的表2這樣的結果

Name    town
Sarah   Egypt
John    Germany
Mick    France
Sarah   Egypt
Sarah   USA
John    Germany
Mick    France
John    Germany

Name    town    duplicate
Sarah   Egypt      1
John    Germany    1
Mick    France     1
Sarah   Egypt      2
Sarah   USA        1
John    Germany    2
Mick    France     2
John    Germany    3

Answer 1

您應該使用聚合函數count（*）並進行分組

select name, town, count(*) as duplicated 
from my_table 
group by  name, town

Answer 2

嘗試這個，

創建表：

create table test (name varchar(20), town varchar(20));

插入語句：

insert into test value('Sarah','Egypt');
insert into test values('John','Germany');
insert into test values('Mick','France');
insert into test values('Sarah','Egypt');
insert into test values('Sarah','USA');
insert into test values('John','Germany');
insert into test values('Mick','France');
insert into test values('Sarah','Egypt');

查詢：

set @x=1;
set @checkname='';
set @checktown='';
select name, town ,row_number
from ( select name, town, if(@checkname = name && @checktown = town,@x := @x + 1 ,@x := 1) as row_number,
@checkname := name, @checktown := town
from test
order by name, town 
) a 

Answer 3

您可以使用以下查詢：

SET @row_number:=1;
SET @name:='';
SET @town:='';
    SELECT @row_number:=CASE WHEN @name=name and @town=town THEN @row_number+1 
      ELSE 1 END AS row_number, @name:=name, @town:=town
    FROM Table1 order by name, town;

在此處檢查SQL