Sometimes after a table has been created in a database, we find that it is advantageous to add an index to that table to speed up queries involving this table (to understand what an index is and how it can help speed up SQL queries, please see the INDEX section). To do this in SQL...
ALTER TABLE tb_book ADD UNIQUE index ix_title(title); -- 建表后添加全文索引 ALTER TABLE tb_book ADD FULLTEXT index ix_content(content); -- 查询时使用全文索引 SELECT * FROM tb_book MATCH(content) ANGAINST(‘胜利’); -- 建表后添加组合索引 ALTER TABLE tb_book ADD INDEX ix_book(title...
Microsoft.SqlServer.Management.SMO.Index -argumentlist $tb, "clusprimindex" $cp.IsClustered = $true; $cp.IndexKeyType = [Microsoft.SqlServer.Management.SMO.IndexKeyType]::DriPrimaryKey; #Create and add an indexed column to the index. $cpcol = New-Object -TypeName Microsoft.Sql...
CREATE UNIQUE INDEX index1 ON schema1.table1 (column1 DESC, column2 ASC, column3 DESC); 主要方案:从SQL Server 2016 (13.x) 和 SQL 数据库开始,可针对列存储索引使用非聚集索引来提高数据仓库查询性能。 有关详细信息,请参阅列存储索引 - 数据仓库。有...
Using SQL Server Management Studio to create an index with nonkey columns Show 2 more Applies to: SQL Server Azure SQL Database Azure SQL Managed Instance SQL database in Microsoft FabricThis article describes how to add included (or nonkey) columns to extend the functionality of nonclustere...
Modifies an existing table or view index (rowstore, columnstore, or XML) by disabling, rebuilding, or reorganizing the index; or by setting options on the index.
Modifies an existing table or view index (rowstore, columnstore, or XML) by disabling, rebuilding, or reorganizing the index; or by setting options on the index.
To add an index expression, click the Add Column Expression (+) icon; this adds a column name here and in Column Expression, where you can edit it. To delete an index expression, click the Remove Column Expression (X) icon; to move an index expression up or down in the list, click ...
create unique index name_index ontb(name); Ⅲ 创建复合索引 代码语言:javascript 复制 create index dept_name_index ontb(dept,name); ③ 创建索引的第二种方式 先删除之前创建的索引以后,再进行这种创建索引方式的测试; 语法:alter table 表名 add 索引类型 索引名(字段) ...
CREATE UNIQUE INDEX user_index ON user (id); 复制代码 1. 2. 3. 删除索引 ALTER TABLE user DROP INDEX user_index; 复制代码 1. 2. 3. 约束 SQL 约束用于规定表中的数据规则。 如果存在违反约束的数据行为,行为会被约束终止。 约束可以在创建表时规定(通过 CREATE TABLE 语句),或者在表创建之后规定...