用省略号将nvarchar（max）截断为nvarchar（n）

Question

What's the quickest way to convert nvarchar(max) to nvarchar(n) and indicate there's more data?

eg: convert the column Address to nvarchar(100) and if Address is larger than 100 characters then replace the last 3 characters with "..."

Answer 1

UPDATE t
SET t.Address = SUBSTRING(t.Address, 1, 97) + '...'
FROM TableName t
WHERE LEN(t.Address) > 100;

ALTER TABLE dbo.TableName
  ALTER COLUMN Address NVARCHAR (100);

Answer 2

UPDATE Table
 SET [Address] =   CASE 
                       WHEN LEN([Address]) > 100 
                       THEN CAST([Address] AS NVARCHAR(97)) + N'...'
                       ELSE CAST([Address] AS NVARCHAR(100)) 
                   END

now change the data type of your column since all the data more than 100 characters will be truncated after the above statement.

ALTER TABLE TableName
ALTER COLUMN [Address] NVARCHAR(100)
GO