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Making the Move from Sybase to SQL Server

By : Sayed Geneidy
Aug 30, 2003

Page 4 / 4

Optimizer Hints

MSSQL Server allows for optimizer hints on SELECT, INSERT, UPDATE, and DELETE statements. Sybase allows optimizer hints only on SELECT statements.

The MSSQL Server vs. Sybase GUI approach:

Sybase	SQL Server
Use a text-based query analysis tool called SHOWPLAN	Use Query Analyzer
Command to enable SHOWPLAN from within ISQL SET SHOWPLAN ON GO	Command to enable SHOWPLAN_ALL or SHOWPLAN_TEXT from query analyzer SET SHOWPLAN_ALL GO

Temporary Table Names

Type of table name	Maximum length
SQL Server table name	128
SQL Server temporary table name	116
Sybase table name	30
Sybase temporary table name	13

Data Types

Data types	Sybase	SQL Server
char(n)	255	8000
varchar(n)	255	8000
nchar(n)	255	4000
nvarchar(n)	255	4000
binary	255	8000
varbinary	255	8000

Notes:

1) The bit data type in MSSQLServer can be set to 0, 1, or NULL.

2) The bit data type in Sybase does not allow nulls.

Identity Columns

Sybase	SQL Server
Numeric(x,0)	Tinyint,smallint,int,decimal(x,0) or numeric(x,0)

Print Syntax

All PRINT statements that use substitution syntax must be changed to RAISERROR statements during the conversion process.

Conclusion

Converting a Sybase to SQL Server is a feat that can be accomplished, but there are a number of differences between the two products that must be addressed. Depending on the size of your application, this conversion could turn into a lengthy process. You don't have to rewrite the whole application, but there are a fair amount of show stoppers. However, look at the bright side: I can't think of an easier conversion between two major database packages than this one, and a successful conversion is highly probable because of the products many similarities. Happy migrating.

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