sql字符串连接函数（mssqlmysqloracle)

mysql向表中某字段后追加一段字符串:
update table_name set field=concat(field,'',str)

mysql 向表中某字段前加字符串
update table_name set field=concat('str',field)

返回结果为连接参数产生的字符串。如有任何一个参数为null ，则返回值为 null。

oracle字符串连接函数

select *
from a
where (substr(value, 0, 2) || '-' || substr(value, 2, 5) || '-' ||
substr(value, 8, 9)) not in (select b from data);
或者直接更新value

update a set value=(substr(value, 0, 2) || '-' || substr(value, 2, 5) || '-' ||
substr(value, 8, 9));
如果不是oracle 的话substr 换成substring

ms sql 字符串连接

create table test(id int,txt varchar(10))
insert test
select 1, 'aaa ' union all
select 1, 'bbb ' union all
select 2, 'ccc ' union all
select 3, 'ddd ' union all
select 3, 'eee ' union all
select 3, 'fff '
--select * from test
go

create function gettxt(@id int)
returns varchar(8000)
as
begin
declare @s varchar(8000)
set @s= ' '
select @s=@s + '； ' +txt from test where id=@id
--return @s
return stuff(@s,1,1, ' ')
end
go

select id,dbo.gettxt(id) txt from test group by id
go

drop function gettxt
drop table test