SQL string connection function (MSSQL MySQL Oracle)

SQL string connection function (MSSQL MySQL tutorial Oracle)
MySQL String connection concat function
How to use:
Concat (STR1,STR2,...)

MySQL appends a string to a field in the table:
UPDATE table_name set FIELD=CONCAT (field, ', str ')

MySQL adds a string before a field in the table
UPDATE table_name set FIELD=CONCAT (' str ', field)

Returns a string resulting from a connection parameter. If any of the arguments are null, the return value is null.

Oracle string Join functions

SELECT *
From a
Where (substr (value, 0, 2) | | '-' || substr (Value, 2, 5) | | '-' ||
substr (Value, 8, 9)) not in (select B from data);
or update value directly

Update a set value= (substr (value, 0, 2) | | '-' || substr (Value, 2, 5) | | '-' ||
substr (Value, 8, 9));
If it's not Oracle, SUBSTR replace substring.

MS SQL string Connection

create   table   Test (id   int,txt   varchar)
insert   Test
select   1, ' AAA '    union   all
select   1, ' BBB '    Uni on   all
select   2, ' CCC '    union   all
select   3, ' DDD ' &N bsp;  union   All
select   3, ' eee '    union   all
Select &nb Sp 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