如何在MySQL中将逗号分隔的字段扩展为多行 | 如何在MySQL中将逗号分隔的字段扩展为多行

本文介绍了如何在MySQL中将逗号分隔的字段扩展为多行的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

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

我想运行产生以下输出的查询

I'd like to run a query that produces the following output

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

推荐答案

如果您不介意使用游标，请参见以下示例:

If you don't mind using a cursor, here's an example:


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

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