The TableDirect // type is only for OLE DB. cmd.CommandType = commandType; cmd.Parameters.AddRange(parameters); conn.Open(); return cmd.ExecuteNonQuery(); } } } // Set the connection, command, and then execute the command and only return one value. public static Object ExecuteSc...
With this command, the column is no longer used as a primary key. It does not delete the column. Composite KeysA composite key is a primary key which that consists of multiple columns. The table below has a composite key on 3 columns: FirstName, LastName, and Phone. CREATE...
-- 在 db_zhuzi 库下创建一张名为 zz_user 的用户表 CREATE TABLE `db_zhuzi`.`zz_user` ( -- 用户ID字段:int类型、不允许为空、设为自增列、声明为主键 `user_id` int(8) NOT NULL AUTO_INCREMENT PRIMARY "i_p_id" COMMENT '用户ID', -- 用户名称字段:字符串类型、运行为空、默认值为“新...
insertCommand.ExecuteNonQuery(); } 将表值参数传递给参数化 SQL 语句下面的示例演示如何使用包含将表值参数作为数据源的 SELECT 子查询的 INSERT 语句向 dbo.Categories 表插入数据。 将表值参数传递给参数化 SQL 语句时,必须使用 SqlParameter 的新TypeName 属性指定表值参数的类型名称。 此 TypeName 必须与先前在...
For example, an ALTER TABLE command fails if another user has an open transaction on the specified table. 4.2.2 Data Manipulation Language (DML) Commands Data manipulation language (DML) commands query and manipulate data in existing schema objects. These commands do not implicitly commit the ...
The SelectCommand must also return at least one primary key or unique column. If none are present, an InvalidOperation exception is generated, and the commands are not generated. The SqlCommandBuilder also uses the Connection, CommandTimeout, and Transaction properties referenced by the SelectCommand....
Can I have a primary key as a non-unique column Can I pass parameter to an ALTER DATABASE command Can I prevent deadlock during concurrent delete Can I print to file using T- SQL Can I sort an SQL table? Can I sort row without order by clause Can I UPDATE, then INSERT if no rec...
U1: Rs1=Command1.Execute("insert sometable EXEC usp_someproc"); U2: Rs2=Command2.Execute("select colA from sometable"); 用户请求 U1 执行的存储过程已获取会话互斥体。 如果执行该存储过程花费了很长时间,SQL Server 数据库引擎会认为存储过程正在等待用户的输入。 用户等待 U2 的结果集时,用户请求 ...
When the transaction manager receives a commit request, it sends a prepare command to all of the resource managers involved in the transaction. Each resource manager then does everything required to make the transaction durable, and all transaction log buffers for the transaction are flushed to dis...
-- Execute a resumable online index create statement with MAXDOP=1 CREATE INDEX test_idx ON test_table WITH (ONLINE = ON, MAXDOP = 1, RESUMABLE = ON); -- Executing the same command again (see above) after an index operation was paused, resumes automatically the index create operation. -...