Question

如何计算Phone中的重复项？

例如：

State   Zip Areacode    Phone
A       123 1           989
b       234 2           989
c       345 3           989
d       456 4           123
e       567 5           123
f       678 6           234
g       678 7           234

预期结果：

State   Zip Areacode    Phone   row_count
A       123 1           989     1
b       234 2           989     2
c       345 3           989     3
d       456 4           123     1
e       567 5           123     2
f       678 6           234     1
g       678 7           234     2

Answer 1

这是一个Window function问题。对于较旧的MySQL版本（ <8.0 ），我们可以使用Session variables对其进行仿真。请尝试以下操作：

0    20181010125200000000
Name: Timestamp, dtype: object

PS：：OP具有confirmed，SELECT t1.State, t1.Zip, t1.Areacode, @row_count := CASE WHEN @ph = t1.Phone Then @row_count + 1 ELSE 1 END AS row_count, @ph := t1.Phone AS Phone FROM (SELECT State, Zip, Areacode, Phone FROM your_table ORDER BY Phone) AS t1 CROSS JOIN (SELECT @row_count := 1) AS init1 CROSS JOIN (SELECT @ph := '') AS init2分区中的编号可以是任何数字。

Answer 2

如果要通过电话号码订购，一个简单的解决方案是：

SELECT State, Zip, Areacode, Phone, `Index` FROM (
    SELECT State, 
           Zip, 
           Areacode, 
           Phone, 
           @Idx := IF(@previous_phone=Phone, IFNULL(@Idx,0)+1,1) as Index,
           @previous_phone := Phone
    FROM table 
    ORDER BY Phone
) t;

这将仅保留先前的电话号码并在索引更改时重置索引。

如果您要为组合的“ Zip Area Phone”计算重复次数，则可以根据CONCAT(Zip,Area,Phone)进行比较，例如

SELECT State, Zip, Areacode, Phone, `Index` FROM (
    SELECT State, 
           Zip, 
           Areacode, 
           Phone, 
           @Idx := IF(@previous_phone=CONCAT(Zip, Area, Phone), IFNULL(@Idx,0)+1,1) as Index, 
           @previous_phone := CONCAT(Zip, Area, Phone)
    FROM table 
    ORDER BY Zip, Area, Phone
) t;

Answer 3

下面是通过比较多个列来查找重复记录的MySQL查询

SELECT 
    Zip, COUNT(Zip),
    Areacode,  COUNT(Areacode),
    Phone,      COUNT(Phone)
FROM
    TableName
GROUP BY 
    Zip , 
    Areacode , 
    Phone
HAVING  COUNT(Zip) > 1
    AND COUNT(Areacode) > 1
    AND COUNT(Phone) > 1;

将TableName替换为Mysql表名称。

Reference

如何索引列中具有重复值的行？

3 个答案: