C# sqlserverce Database Objects

C# sqlserverce Database Objects

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Database Objects

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The following table specifies the maximum size limitations for several database objects defined in Microsoft SQL Server Compact databases.

Category	Object	Maximum size limitations
Storage	Column name	128 characters
	Columns in a table	1024
	Row size	8060 bytes
	Database password	40 characters
	Database size	4 GB 1
	Database size increase	1-page or 16-page increments, depending on table size
	Page size	4 KB
	Sessions	256
	Size of BLOB (ntext and image) column	2 GB
	Table name	128 characters
	Table size	Unlimited
Queries	Characters in an SQL statement	Unlimited
	Columns in a cursor	1024
	Columns in an ORDER BY, GROUP BY, or DISTINCT clause	10242
	Levels of nested subqueries	Unlimited
	Named parameters	Supported
	Operands in a query	Unlimited
	Tables in a join	Unlimited
Indexes	BLOB columns	Cannot be indexed
	Bytes in an index key	5123
	Columns in an index	16
	Indexes per table	249
Constraints	PRIMARY KEY, UNIQUE, Default constraints, and FOREIGN KEY	Supported 4
	Constraints per table	249

1The default maximum size is 128 MB for devices and 256 MB for desktops.

2This limit is applied only if a storage engine temporary table is used for implementing ORDER BY. If the Query Processor can leverage an existing index, there is no maximum column-number limit.

3 Longer keys are supported, but the data is truncated and a checksum is added at the end. For equivalence operations, this works fine (unless two checksums happen to be the same). This becomes a concern when using an ORDER BY clause. The ordering beyond the key length is returned based on the checksum and not the actual value.

4For every PRIMARY KEY and UNIQUE constraint defined on a table, an index is created on those columns. These indexes all count against the total number of indexes allowed for a table. Also, some data types (ntext, image) cannot be used as primary key columns because they cannot be indexed