ALTERTABLEtable_nameADDPRIMARYKEY (column_name); 以下SQL 语句在 employees 表中添加了一个主键: 实例 ALTERTABLEemployees ADDPRIMARYKEY(employee_id); 6. 添加 FOREIGN KEY ALTERTABLEchild_tableADDCONSTRAINTfk_nameFOREIGNKEY (column_name)REFERENCESparent_table (column_name); 以下SQL 语句在 orders 表中添...
Flink SQL> show databases; +---+ | database name | +---+ | default_database | | alan_test | +---+ 2 rows in set Flink SQL> ALTER database default_catalog.alan_test set('createdate'='2023-11-20'); [INFO] Execute statement succeed. Flink SQL> show databases; +---+ | data...
ExampleGet your own SQL Server ALTERTABLECustomers ADDEmail varchar(255); ALTER TABLE - DROP COLUMN To delete a column in a table, use the following syntax (notice that some database systems don't allow deleting a column): ALTERTABLEtable_name ...
5. 选择数据库 进入数据库:use db_name; 查看当前所选的数据库: select database(); b. 操作表 1. 创建表 创建一个员工表employee create table employee( id int primary key auto_increment, name varchar(20) unique, gender bit not null, birthday date, entry_date date, job varchar(40), salary...
A mismatched SID can occur when you have restored a database from another server and have a database user mapped to a SQL Server login. You can use theWITH LOGINclause to correct this situation by replacing the user SID in the database with the login SID from the server. ...
In such databases you must instead use the new catalog views. The new catalog views take into account the separation of principals and schemas that was introduced in SQL Server 2005. For more information about catalog views, see Catalog Views (Transact-SQL). Permissions To change the name of...
Use the QUIESCE RESTRICTED and UNQUIESCE clauses to put the database in and take it out of the quiesced state. This state enables database administrators to perform administrative operations that cannot be safely performed in the presence of concurrent transactions, queries, or PL/SQL operations....
USE AdventureWorks; GO ALTER TABLE Production.TransactionHistoryArchive WITH NOCHECK ADD CONSTRAINT PK_TransactionHistoryArchive_TransactionID PRIMARY KEY CLUSTERED (TransactionID) WITH (FILLFACTOR = 75, ONLINE = ON, PAD_INDEX = ON); GO このような例では、クラスター化された主キーの適用中にペー...
默认值为OFF“超大规模”Azure SQL 数据库除外。 对于“超大规模”中的所有索引生成作,除非使用可恢复索引生成,否则始终 SORT_IN_TEMPDBON。 对于可恢复索引生成,SORT_IN_TEMPDB 始终OFF。 上 用于生成索引的中间排序结果存储在其中 tempdb。 这可以减少创建索引所需的时间。 但是,这会增加索引生成期间所使用的磁盘...
Specifies the name of the SQL Server login that is being changed. Domain logins must be enclosed in brackets in the format[<domain>\<user>]. ENABLE | DISABLE Enables or disables this login. Disabling a login doesn't affect the behavior of logins that are already connected. (Use theKILLsta...