如何在不默认为null的情况下将db object数据类型从varchar更改为nvarchar？

只需添加

+ CASE WHEN IS_NULLABLE='NO' THEN ' NOT NULL' ELSE '' END

另外，您需要添加

CHARACTER_MAXIMUM_LENGTH

nvarchar

至于存储过程中的参数，我最好手动进行。

编辑
完整查询

SELECt cmd = 'alter table [' + c.table_schema + '].[' + c.table_name  + '] alter column [' + c.column_name + '] nvarchar(' +CASE WHEN CHARACTER_MAXIMUM_LENGTH<=4000       THEN CAST(CHARACTER_MAXIMUM_LENGTH as varchar(10)) ELSE 'max' END+')'  + CASE WHEN IS_NULLABLE='NO' THEN ' NOT NULL' ELSE '' END,*FROM information_schema.columns cWHERe c.data_type='varchar' ORDER BY CHARACTER_MAXIMUM_LENGTH desc