字段中的null值需要先更新掉,不能为null才能执行。 update 表名 set columnname='0' where columnname is null alter table 表名 alter column 字段名称 字段类型 not null alter table 表名 add constraint DF_表名_字段名 default 0 for 字段名 with values...
Most of you must have come across the pain of adding a not null column with a default value to an existing big table. It takes minutes to add columns. I recently found out that this problem has been resolved in SQL Server 2012. Let’s look into some ways to resolve this in versions ...
CREATE TABLE dbo.Tmp_testadd ( id int NOT NULL IDENTITY (1, 1), code nvarchar(20) NOT NULL, name nvarchar(50) NULL, remark nvarchar(200) NULL, createdate datetime NULL, createuserid nvarchar(30) NULL, testaddcolumn nvarchar(50) NULL, endamount money NULL, testid int NOT NULL, test...
ADD vv INT NULL --修改列定义 --如果缺了Null或者NOT NULL,那么会根据数据库的默认配置来设 --如果列有索引,当列类型为varchar、nvarchar、varbinary时才能修改,且新大小要比原大小更大 ALTER TABLE t ALTER COLUMN v VARCHAR(10) --这里会设置成NULL --修改列的排序规则,注意不能同时指出是否可以为NULL,否...
--增加整形字段可以这样写ALTERTABLETABLE_NAMEADDCOLUMN_NAMEINTNOTNULLDEFAULT(0)--增加字符型字段可以这样写ALTERTABLETABLE_NAMEADDCOLUMN_NAMENVARCHAR(50)NOTNULLDEFAULT('') 分组统计时避免使用count(*) IFOBJECT_ID('DBO.Customer','U')ISNOTNULLDROPTABLEDBO.CustomerGOCREATETABLEDBO.Customer(Customeridintn...
早期版本(Sql Server2008R2及以前)添加非空栏位(要求有默认值)是对表中的所有数据行依次修改调整 我们通过一个简单的实例来看下 Sql 2008R2 SP2 Code Create database tadnull go use tadnull go create table t2(id int not null identity (1,1),dystr varchar(20),fixstr char(30)); ...
DEFAULT (0)--Optional Default-Constraint. WITH VALUES --Add if Column is Nullable and you want the Default Value for Existing Records. Notes: Optional Constraint Name: If you leave out CONSTRAINT D_SomeTable_SomeCol then SQL Server will autogenerate a Default-Contraint with a ...
简介:Sql Server 增加字段、修改字段、修改类型、修改默认值 1、修改字段名: alter table 表名renamecolumn A to B 2、修改字段类型: alter table 表名 alter column 字段名 type not null 3、修改字段默认值 alter table 表名 add default (0) for 字段名 with values ...
I understand that when adding a column to a table containing data in SQL server, the column must have a NULL option or a default. Otherwise what would SQL Server pad the new rows with? I am at a loss as to why I can't add a NOT NULL column to an empty table however. ...
id serial, // ---自增，item--- username char(20) not null, //---非空--- nation char(20) default 'China' //---默认值--- )修改表的时候：添加：alter table table_name add(column_name char(120) default '默认值')修改:alter table table_name modify(old_name char...