@alikon Please try the following:

• Add a new article with a title and fill in a new tag (= adhoc tag), then save. The article is saved.
• Repeate the above step. You get the error message:

Save failed with the following error: SQL=INSERT INTO udzse_contentitem_tag_map

Another test case:

• Add to an existing article two or more tags: only the first tag is saved.

Under mssql to get the following error when you try to add a new tag to an existing article:

Save failed with the following error: [Microsoft][SQL Server Native Client 11.0][SQL Server]Error converting data type varchar to bigint.SQL=INSERT INTO ufv5y_tags VALUES ('1','1','17','18','2015-03-05-20-25-47','2015-03-05-20-25-47','Stiege','('''')','1','((0))','2015-03-05 20:25:47','1','{}',' ',' ','{}','((0))','2015-03-05 20:25:47','('''')','((0))','2015-03-05 20:25:47','{}','{}','((0))','*','((1))','2015-03-05 20:25:47','2015-03-05 20:25:47')

@waader
i'm experiencing the same issues on postgresql

where the driver return a bad default value for fields of type (TEXT, CHARACTER VARYING) declared NOT NULL WITH DEFAULT , for postgresql i have a fix ,
i guess for MSSQL the same reason
if you can help me on sqlsrv runnnig this query and report back the results

    SELECT column_name as Field, data_type as Type, is_nullable as \'Null\', column_default as \'Default\'
           FROM information_schema.columns WHERE table_name = #__tags

maybe i will able to find a fix to mssql too

@alikon I modified your sql slightly to

SELECT column_name as Field, data_type as Type, is_nullable as 'Null', column_default as 'Default'
FROM information_schema.columns WHERE table_name = 'aqmag_tags'

and this gives the following back:

id bigint NO NULL
parent_id bigint NO ((0))
lft int NO ((0))
rgt int NO ((0))
level bigint NO ((0))
path nvarchar NO ('')
title nvarchar NO NULL
alias nvarchar NO ('')
note nvarchar NO ('')
description nvarchar NO NULL
published smallint NO ((0))
checked_out bigint NO ((0))
checked_out_time datetime NO ('1900-01-01T00:00:00.000')
access bigint NO ((0))
params nvarchar NO NULL
metadesc nvarchar NO NULL
metakey nvarchar NO NULL
metadata nvarchar NO NULL
created_user_id bigint NO ((0))
created_time datetime NO ('1900-01-01T00:00:00.000')
created_by_alias nvarchar NO ('')
modified_user_id bigint NO ((0))
modified_time datetime NO ('1900-01-01T00:00:00.000')
images nvarchar NO NULL
urls nvarchar NO NULL
hits bigint NO ((0))
language nvarchar NO NULL
version bigint NO ((1))
publish_up datetime NO ('1900-01-01T00:00:00.000')
publish_down datetime NO ('1900-01-01T00:00:00.000')

@waader can you send the results in a more viewable (tabular/matrix) way even with screenshot I'm not sure I've fully understand the results

Of course:

Thx now is clear, let me prepare a fix.....

@waader
i'm not so confident with mssql is more diffcult blind code

@test works much better now, but there is one case I would like you to try:

• add a new article and add three tags on the fly: test1, test2, test3
• then hit save
• only test1 gets saved
• it is possible now to add further tags, but no more than one at a time

@waader
should be fixed now i've tested with 7 tags
can you confirm

@alikon works fine with postgresql now. Mssql is another chapter and not in the scope of this pr. Thanks!

Confirmed issue
Confirmed PR resolved it

Two tests setting RTC

Thank you @alikon! Merged.