SQL Server 2019

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create table mon ( 
monet text, monev nvarchar(20),
monetm money, monevm money);
insert into mon (monet, monev) values('49.0000000000','49.0000000000');
1 rows affected

select * from mon;


monet
monev
monetm
monevm


49.0000000000
49.0000000000
null
null


update mon set monevm = cast(monev as decimal(20,10))from mon;
1 rows affected

update mon set monetm = cast(monet as decimal(20,10))from mon;
Msg 529 Level 16 State 2 Line 1
Explicit conversion from data type text to decimal is not allowed.

update mon set monetm = cast(
                        cast(monet as varchar)
                        as decimal(20,10))from mon;
1 rows affected

select * from mon;


monet
monev
monetm
monevm


49.0000000000
49.0000000000
49.0000
49.0000