Question

select id, ips from users;

查询结果

id    ips
1     1.2.3.4,5.6.7.8
2     10.20.30.40
3     111.222.111.222,11.22.33.44
4     1.2.53.43

我想运行一个产生以下输出的查询

user_id     ip
1           1.2.3.4
1           5.6.7.8
2           10.20.30.40
3           111.222.111.222
3           11.22.33.44   
4           1.2.53.43

Answer 1

如果你不介意使用光标，这是一个例子：


set nocount on;
-- create sample table, @T
declare @T table(id int, ips varchar(128));
insert @T values(1,'1.2.3.4,5.6.7.8')
insert @T values(2,'10.20.30.40')
insert @T values(3,'111.222.111.222,11.22.33.44')
insert @T values(4,'1.2.53.43')
insert @T values(5,'1.122.53.43,1.9.89.173,2.2.2.1')

select * from @T

-- create a table for the output, @U
declare @U table(id int, ips varchar(128));

-- setup a cursor
declare XC cursor fast_forward for select id, ips from @T
declare @ID int, @IPS varchar(128);

open XC
fetch next from XC into @ID, @IPS
while @@fetch_status = 0
begin
        -- split apart the ips, insert records into table @U
        declare @ix int;
        set @ix = 1;
        while (charindex(',',@IPS)>0)
        begin
            insert Into @U select @ID, ltrim(rtrim(Substring(@IPS,1,Charindex(',',@IPS)-1)))
            set @IPS = Substring(@IPS,Charindex(',',@IPS)+1,len(@IPS))
            set @ix = @ix + 1
        end
        insert Into @U select @ID, @IPS

    fetch next from XC into @ID, @IPS
end

select * from @U

Answer 2

我不认为这是您想要使用查询做的事情，但您宁愿在您的表示逻辑中执行此操作。该数据库仅用于存储和检索数据。格式化数据并在表示层中显示，通常与PHP / ASP.NET /其他内容结合使用。

Answer 3

之前已经出现了好几次。这是一个答案：

https://stackoverflow.com/questions/3936088/mysql-split-comma-separated-list-into-multiple-rows

如何在MySQL中将逗号分隔的字段扩展为多行

3 个答案: