SQL Server ->> 生成代码把表字段从NULL改为NOT NULL

一般我们用SELECT .... INTO语句生成的表字段都是允许为NULL。而如果我们需要改成NOT NULL呢

select ‘ALTER TABLE dbo.XXXXXXX ALTER COLUMN ‘ +
QUOTENAME(c.name) + ‘ ‘ + t.name +
case when t.name in (‘nvarchar‘,‘nchar‘)
        then ‘(‘+ cast(c.max_length/2 as nvarchar) +‘)‘
    when t.name in (‘varchar‘,‘binary‘, ‘char‘, ‘varbinary‘)
        then ‘(‘+ cast(c.max_length as nvarchar) +‘)‘
else ‘‘ end + ‘ NOT NULL‘
from sys.columns c join sys.types t on c.system_type_id = t.system_type_id
where object_id = object_id (‘dbo.XXXXXXX‘) and t.name <> ‘sysname‘
order by column_id 

有时需要准备数据库设计文档，里面的物理设计这块需要填写像这样的表

如果比本身已经建立好在数据库中，我们可以通过一条脚本生成

select c.name, t.name + case when t.name in (‘nvarchar‘,‘nchar‘)
        then ‘(‘+ cast(c.max_length/2 as nvarchar) +‘)‘
    when t.name in (‘varchar‘,‘binary‘, ‘char‘, ‘varbinary‘)
        then ‘(‘+ cast(c.max_length as nvarchar) +‘)‘
else ‘‘ end, case when c.is_nullable = 1 then ‘Yes‘ ELSE ‘No‘ end
from sys.columns c join sys.types t on c.system_type_id = t.system_type_id
where object_id = object_id (‘dbo.XXXXXXX‘) and t.name <> ‘sysname‘
order by column_id