Create Data Comparisons

This topic focuses on information that may be unfamiliar to you. It does not include all step and field descriptions.

Important: Data Compare uses built-in .NET data types, which can have a lower range or precision than the actual data type. If you compare data for an object that has a higher data type range or precision, an error is generated when you complete the Data Compare wizard. Review the following data type range and precision limitations for all supported platforms:

Decimal (numeric) data: 28-29 significant digits
Date and time values: from 00:00:00 January 1, 0001 A.D. to 23:59:59 December 31, 9999 A.D., precision 10-7 seconds
Time intervals: from +107 to -107 days, precision 10-7 seconds
Floating point numbers: from ±5.0 × 10−324 to ±1.7 × 10308, 15-16 significant digits
Text data: up to 2 Gigabytes
Binary data: up to 2 Gigabytes

To create a new comparison

Right-click one or more tables or views in the Object Explorer and select Data Compare.
Tip: You can also select Tools | Compare | Data Compare to open Data Compare.

Complete the wizard. Review the following for additional information:

Map Source Objects to Target	Description
Type	Indicates whether target and source objects are tables or views: - The object is a table - The object is a view - The object type is unknown The left icon indicates source object's type. The right icon indicates the target object's type. In this example, the source object is a table and the target object type is unknown.
Target object	Expand the list to select a target table or view you want to compare to the selected source object. Repeat this process for each row that contains a source object you want to compare. Tip: Click Map all to automatically map all objects in the target that have the same name as an object in the source database.
Columns Mapped	Click to open Column Selection window to customize column mapping, set comparison key and specify filters. You can map a target column to any column that contains a data type that is compatible or can be converted to a compatible data type. In case of automatic mapping primary key columns or columns with unique index are selected as comparison key. When you map columns manually, you can select any column as a comparison key. If you manually map columns, you can also do the following in the Column Selection window: Exclude columns from comparison. Clear the Compare checkbox beside each source column you want to exclude from comparison. Limit the scope of the compare by specifying filters. Enter the filtering criteria in the Source Where clause and/or Target Where clause fields. Use SQL syntax to specify filter criteria. For example, if you want to compare only those source records where value for bitpos is greater than 10 and sum is smaller than 100, enter bitpos > 10 AND sum < 100 in the Source Where clause field. Tip: You can map a target column to multiple columns on the source database.
Select Comparison Options Page	Description
Comparison	Select the options for the comparison. See Data Types Affected by Comparison Options for more information.
Record types to Include in Comparison	Select whether to load records which have a particular comparison type. Excluding record types helps save disc space and increase compare performance.
Save Comparison	Select Save Comparison if you want to save the project without actually comparing data. Note: Saved comparison projects can be send to Automation (Select Automation on the data compare results toolbar or go to Tools \| Automation and select Data Compare under Database activities).

Tips:

To quickly make changes to the current project, click .
Only one compare can be open at a time. To avoid losing your work, save the current compare before creating a new one.