UNIQUE 子句使用的直欄清單,與表格 tablename 中已存在之另一個 UNIQUE 子句或 PRIMARY KEY 或 UNIQUE 限制之 PRIMARY KEY 子句的直欄清單相同。唯一限制不可以重複。 name 是限制名稱(如果已指定或已存在)。如果未指定限制名稱, name 就是UNIQUE 子句直欄清單中指定的第一個直欄名稱後面再加三個句點。 無法處...
--Create the partition scheme and function, align this to the number of CPU cores 1:1 up to 32 core computer -- so for below this is aligned to 16 core system CREATE PARTITION FUNCTION [pf_hash16] (tinyint) AS RANGE LEFT FOR VALUES (0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10,...
42891 重複する UNIQUE 制約がすでに存在します。 -541 42892 DELETE 規則とトリガー・イベントに互換性がないため、参照制約とトリガーは許可されません。 -675 42893 別のオブジェクトが依存しているため、オブジェクトまたは制約のドロップ、変更、または転送を行ったり、そのオブジェクトの権...
[ NOT FOR REPLICATION ] | CHECK [ NOT FOR REPLICATION ] ( logical_expression ) } <table_index> ::= { { INDEX index_name [ UNIQUE ] [ CLUSTERED | NONCLUSTERED ] ( column_name [ ASC | DESC ] [ ,... n ] ) | INDEX index_name CLUSTERED COLUMNSTORE [ ORDER (column_name [ , ....
A maximum frequency of 1 can be found in columns with unique values.The density vector contains one density for each prefix of columns in the statistics object. For example, if a statistics object has the key columns CustomerId, ItemId and Price, density is calculated on each of the ...
The code in Figure 6 shows a simple example for writing a non-recursive CTE that returns yearly customer's sales order values. Obviously you could achieve the same results without using a CTE, but suppose with each row you also want to return the previous year's total value, and the diff...
(this is an OFFLINE operation)-- Consider using bulk loading techniques to speed it upALTERTABLE[dbo].[latch_contention_table]ADD[HashValue]AS(CONVERT([tinyint],abs(binary_checksum([hash_col])%(16)),(0))) PERSISTEDNOTNULL;--Create the index on the new partitioning schemeCREAT...
Count null value from a table for each columns count of columns of stored procedure in sql count of columns with non-zero values Count of unique combinations Count subset of rows in subquery? Count The Number Of Rows Inserted Per Day Count(*) with Partition by producing the wrong result. ...
除了 IO 瓶颈之外，SQL 优化中需要考虑的就是 CPU 运算量的优化了。order by、group by、distinct……...
GetSqlValues(Object[]) Fills an array ofObjectthat contains the values for all the columns in the record, expressed as SQL Server types. GetSqlXml(Int32) Gets the value of the specified column as an XML value. GetStream(Int32)