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id
a
a
a
b
b
c
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a 3
b 2
c 1
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SQL code:
select id,count(1) from tb group by id
SQL code:
SELECT *,(SELECT COUNT(1) from TB WHERE ID=T.ID)AS NUM
from TB T ORDER BY
(SELECT COUNT(1) from TB WHERE ID=T.ID) DESC
SQL code:
select id,count(1) as px from tb order by px desc
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SQL code:
select id,count(1) from tb group by id ORDER BY 2 DESC
SQL code:
select id,count(1) as px from tb order by count(1) desc
SQL code:
---²âÊÔÊý¾Ý---
if object_id('[tb]') is not null drop table [tb]
go
create table [tb]([id] varchar(1))
insert [t
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Backup Database test_database
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isnull(a,b)
¼´Èç¹ý×Ö¶ÎaΪnullÔò·µ»Øb
eg:
select isNUll(a,b) from table_1;
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SQL code:
mysql> select ifnull(null,2);
+----------------+
| ifnull(null,2) |
+------------ ......