4.删除字段:ALTER TABLE 表名 DROP 字段名; 2.添加主键 1.语法:ALTER TABLE 表名 ADD CONSTRAINT 主键名 PRIMARY KEY 表名(主键字段); 3.添加外键 1.语法:ALTER TABLE 表名 ADD CONNSTRAINT 外键名 FOREIGN KEY(外键字段) REFERENCES 关联表名(关联字段); 4.插入单(多)条数据记录(和SQL Server相同,但是...
alter table 表名 add constraint 约束名称 约束类型 (列名) references 被引用的表名称(列名) 例子: alter table emp add constraint jfkdsj foreign key (did) references dept (id) SQL常用命令使用方法: 数据记录筛选: select*from Products:查询出Products表里面的所有信息 select ProductID,ProductName from P...
{ CHECK | NOCHECK } ] | ADD { <column_definition> | <computed_column_definition> | <table_constraint> | <column_set_definition> } [ ,...n ] | [ system_start_time_column_name datetime2 GENERATED ALWAYS AS ROW START [ HIDDEN ] [ NOT NULL ] [ CONSTRAINT constraint_name ] DEFAULT ...
ALTER TABLE table_name { ADD [COLUMN] column_name column_definition | ADD [COLUMN] (column_name column_definition,...) | ADD [CONSTRAINT [symbol]] FOREIGN KEY (fk_column_name) REFERENCES pk_table_name (pk_column_name) | ADD {INDEX|KEY} [index_name] (column_name,...) | ADD {INDE...
Add Multiple Columns in a Table We can also add multiple columns at once to a table. For example, -- add phone and age columns to Customers tableALTERTABLECustomersADDphonevarchar(10), ageint; Here, the SQL command adds thephoneandagecolumns to theCustomerstable. ...
ALTER TABLE ändert eine Tabellendefinition durch Ändern, Hinzufügen oder Löschen von Spalten und Einschränkungen. Mit ALTER TABLE können Sie zudem Partitionen neu zuweisen und erstellen oder Einschränkungen und Trigger deaktivieren und
DROP CONSTRAINT Drops a primary key, foreign key, or check constraint from the table. DROP FEATURE feature_name [ TRUNCATE HISTORY ] 適用於: Databricks SQL Databricks Runtime 14.1 和更新版本 從Delta Lake 資料表中移除功能。 移除影響讀取器和寫入器的功能需要一個兩階段處理過程: ...
如下测试:在5.6中,Alter Table首选使用ALGORITHM=INPLACE算法。其中加字段,加索引,加主键,字段设置默认值都允许在Alter的同时进行DML操作,而更改字段类型则要锁表。 1.加字段 session1: 17:03:40 pe> alter table product_2 add column ext_1 char(10); ...
then it is widely used (living), and finally, it is decommissioned (death). A database administrator during this life cycle might be asked to add, change, and drop columns within an existing table. How can we execute these tasks without using the graphical user interface within SQL Server ...
CREATE TABLE dbo.doc_exd ( column_a INT) ; GO INSERT INTO dbo.doc_exd VALUES (-1) ; GO ALTER TABLE dbo.doc_exd WITH NOCHECK ADD CONSTRAINT exd_check CHECK (column_a > 1) ; GO EXEC sp_help doc_exd ; GO DROP TABLE dbo.doc_exd ; GO ...