Applies to: SQL Server Azure SQL Database Azure SQL Managed InstanceThis topic describes how to create a unique index on a table in SQL Server by using SQL Server Management Studio or Transact-SQL. A unique index guarantees that the index key contains no duplicate values and therefore every ...
For example, assume that a column that is named "column1" is included in the clustered or unique index. When the column value is changed from a larger to a smaller value (such as changing the value from ...
You can create a unique constraint in SQL Server by using SQL Server Management Studio or Transact-SQL to ensure no duplicate values are entered in specific columns that don't participate in a primary key. Creating a unique constraint automatically creates a corresponding unique index. ...
A uniqueifier (or uniquifier as reported by SQL Server internal tools) is a 4-byte value used to make each key unique in a clustered index that allow duplicate key values. This uniqueness is required because each clustering key must point to exactly one record, without the uniqueifier a ...
index 使用index insert 使用insert lock tables 使用lock table process 使用show full processlist select 使用select show databases 使用show databases show view 使用show view update 使用update reload 使用flush shutdown 使用mysqladmin shutdown(关闭MySQL) ...
In addition, both SQL Server 7.0 and 2000 give us the sp_indexoption system stored procedure that allows us to specify locking options on indexes. SQL7 allows us to inspect and set "AllowRowLocks" and "AllowPageLocks," and SQL 2000 gives us the additional options "DisAllowRowLocks" and ...
You can create a unique constraint in SQL Server by using SQL Server Management Studio or Transact-SQL to ensure no duplicate values are entered in specific columns that don't participate in a primary key. Creating a unique constraint automatically creates a corresponding unique index. Note For ...
You can create a unique constraint in SQL Server by using SQL Server Management Studio or Transact-SQL to ensure no duplicate values are entered in specific columns that don't participate in a primary key. Creating a unique constraint automatically creates a corresponding unique index. Note For ...
full textl: 表示全文搜索的索引。 FULLTEXT 用于搜索很长一篇文章的时候,效果最好。用在比较短的文本,如果就一两行字的,普通的 INDEX 也可以。 总结,索引的类别由建立索引的字段内容特性来决定,通常normal最常见。 问题2:在实际操作过程中,应该选取表中哪些字段作为索引?
Just recently, the following question came up in the microsoft.public.sqlserver.server newsgroup: Can someone tell me the difference between a "unique index" and a "unique constraint"? The SQL Server documentation says that a unique constraint automatically creates a unique index to preserve the ...