ALTER TABLE是用于修改已有表结构的 SQL 语句。我们可以通过该语句对表的列、约束以及索引进行添加、修改或删除。设置默认值的任务可以通过ALTER COLUMN来完成。基本语法如下: ALTERTABLEtable_nameALTERCOLUMNcolumn_nameSETDEFAULTdefault_value; 1. 2. 其中,table_name是需要修改的表名,column_name是需要设置默认值的...
其中,table_name指定要修改的表的名称,alter_specification用于指定要进行的修改操作。 修改字段的默认值 要修改字段的默认值,可以使用ALTER TABLE语句的ALTER COLUMN子句。下面是一个示例: ALTERTABLEtable_nameALTERCOLUMNcolumn_nameSETDEFAULTnew_default_value 1. 2. 其中,table_name是要修改的表的名称,column_name...
Alter Table add Column - How do you add a column after say the second column Alter table add constraint primary key clustered identity(1,1) ALTER TABLE ALTER COLUMN (To set the default value) ALTER TABLE Progress? ALTER TABLE SWITCH statement failed. Check constraints or partition function of...
ALTERTABLEdistributorsADDCOLUMNaddressVARCHAR(30); 对现存列改名: ALTERTABLEdistributors RENAMECOLUMNaddressTOcity; 对现存表改名: ALTERTABLEdistributors RENAMETOsuppliers; 向表中增加一个外键约束: ALTERTABLEdistributorsADDCONSTRAINTdistfkFOREIGNKEY(address)REFERENCESaddresses(address) MATCHFULL 兼容性 SQL92ADDCOLUMN...
CREATE TABLE TEST ( ID_NUM INTEGER, NAME INTEGER, VALUE INTEGER, ITEMS_NUM INTEGER, ) And there were some data injected into this table. Now, I need to update the table to change the ID_NUM column as VARCHAR and add formatted UUID as default value. I have followed the ...
alter table table_name alter column column_test set default 'value'; 5. 添加带默认值的字段 Demo: 1 alter table table_name add column column_test vachar(20) not null with default 'value'; 6. 设置字段默认时间为当前时间 Demo: 1 alter table table_name alter column column_test set default ...
ALTER TABLE MyTable ALTER COLUMN CreateDate DATETIME NOT NULL CONSTRAINT DF_Constraint DEFAULT GetDate() So here I'm trying to make my column Not Null and also set the Default value. But getting Incoorect Syntax Error near CONSTRAINT. Am I missing sth? sql sql-server default-value notnul...
如需對應於 SQL 專用權之系統權限的相關資訊,請參閱檢查表格或視圖的專用權時對應的系統權限及檢查特殊類型的專用權時對應的系統權限。 語法 ALTER TABLE表格名稱ADDCOLUMN直欄定義BEFORE直欄名稱ALTERCOLUMN直欄變更DROPCOLUMN直欄名稱CASCADERESTRICTADD唯一限制參照限制核對限制DROPPRIMARY KEYUNIQUEFOREIGN KEYCHECKCONSTRAI...
1、添加列：ALTER TABLE table_name ADD column_name column_definition;2、修改列名和类型：ALTER TABLE table_name ALTER COLUMN column_name TYPE new_data_type;3、修改列的默认值：ALTER TABLE table_name ALTER COLUMN column_name SET DEFAULT default_value;4、修改列的约束：ALTER TABLE table_...
ALTER TABLE [ IF EXISTS ] name ATTACH PARTITION partition_name { FOR VALUES partition_bound_spec | DEFAULT } ALTER TABLE [ IF EXISTS ] name DETACH PARTITION partition_name 其中 action 是以下之一: ADD [ COLUMN ] [ IF NOT EXISTS ]