如何一次调整所有 NVARCHAR(n) 列的大小？

Question

I wonder if something like the following is possible to achieve:

ALTER TABLE dbo.[Foo] 
    ALTER COLUMN * NVARCHAR(500) 
    WHERE Columns NVARCHAR(n) < NVARCHAR(500);

Answer 1

you can use information_schema.columns and build a dynamic sql query to do generate query. Still you need to copy the result and run them manually.

select 'alter table '+TABLE_SCHEMA+'.'+TABLE_NAME+' alter column '+COLUMN_NAME+' NVARCHAR(500)' 
from INFORMATION_SCHEMA.columns 
where DATA_TYPE = 'nvarchar' 
and CHARACTER_MAXIMUM_LENGTH < 500 
and table_name = 'foo' 
and TABLE_SCHEMA = 'dbo'

edited below

use the below code to include null / not null

select 'alter table ['+TABLE_SCHEMA+'].['+TABLE_NAME+'] alter column ['+COLUMN_NAME+'] NVARCHAR(500) '+case when IS_NULLABLE = 'YES' then 'NULL' else 'NOT NULL' end 
from INFORMATION_SCHEMA.columns 
where DATA_TYPE = 'nvarchar' 
and CHARACTER_MAXIMUM_LENGTH < 500 
and table_name = 'foo' 
and TABLE_SCHEMA = 'dbo'