Mapping Data Types

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Attention: The Borland Database Engine (BDE) has been deprecated, so it will not be enhanced. For instance, BDE will never have Unicode support. You should not undertake new development with BDE. Consider migrating your existing database applications from BDE to dbExpress.

In batAppend mode, a batch move component creates the destination table based on the column data types of the source table. Columns and types are matched based on their position in the source and destination tables. That is, the first column in the source is matched with the first column in the destination, and so on.

To override the default column mappings, use the Mappings property. Mappings is a list of column mappings (one per line). This listing can take one of two forms. To map a column in the source table to a column of the same name in the destination table, you can use a simple listing that specifies the column name to match. For example, the following mapping specifies that a column named ColName in the source table should be mapped to a column of the same name in the destination table:


To map a column named SourceColName in the source table to a column named DestColName in the destination table, the syntax is as follows:

DestColName = SourceColName

If source and destination column data types are not the same, a batch move operation attempts a "best fit". It trims character data types, if necessary, and attempts to perform a limited amount of conversion, if possible. For example, mapping a CHAR(10) column to a CHAR(5) column will result in trimming the last five characters from the source column.

As an example of conversion, if a source column of character data type is mapped to a destination of integer type, the batch move operation converts a character value of '5' to the corresponding integer value. Values that cannot be converted generate errors. For more information about errors, see Handling batch move errors.

When moving data between different table types, a batch move component translates data types as appropriate based on the dataset's server types. See the BDE online help file for the latest tables of mappings among server types.

Note: To batch move data to an SQL server database, you must have that database server and a version of Delphi with the appropriate SQL Link installed, or you can use ODBC if you have the proper third-party ODBC drivers installed.

See Also