File Data Types
bcp can handle data in
one of three forms: character (ASCII), native, or Unicode. You have the
choice of which character format is used, depending on the source or
destination of the data file:
The character format (–c)
is the most commonly used of the three data types because it reads or
writes using ASCII characters and carries out the appropriate data type
conversion for the SQL Server representations. The CHAR data type is the default storage type; it uses tabs as field separators and the newline character as the row terminator.
The native format (–n) is used for copying data between servers. This format allows bcp
to read and write using the same data types used by server, which
results in a performance gain. This format does, however, render the
data file unreadable by any other means.
The Unicode option (–w) uses Unicode characters rather than ASCII characters. The NCHAR data type is the default storage type; it uses tabs as field separators and the newline character as the row terminator.
Format Files
By using a format file, you can customize the data file created by bcp or specify complex field layouts for data loads. There are two ways to create a format file: by using interactive bcp and by using the format switch.
Customizing a Format File by Using Interactive bcp
If you do not specify one of the –n, –c, or –w data type format switches, bcp (in or out) prompts you for the following information for each column in the data set:
bcp offers a default
for each of these prompts that you can either accept or reject. If you
accept all the defaults, you wind up with the same format file you
would have by specifying the native format (with the –n switch). The prompts look like this:
Enter the file storage type of field au_id [char]:
Enter prefix length of field au_id [0]:
Enter length of field au_id [11]:
Enter field terminator [none]:
or like this:
Enter the file storage type of field ProductID [int]:
Enter prefix length of field ProductID [0]:
Enter field terminator [none]:
By
pressing the Enter key at the prompt, you accept the default.
Alternatively, you can type your own value at the prompt if you know
the new value and it is different from the default.
Creating a Format File by Using the format Switch
By using the format
option, you can create a format file without actually transferring any
data. Here is an example of creating a format file for the SalesOrderHeaderAdventureWorks2008 database: table in the
C:> BCP AdventureWorks2008.Sales.SalesOrderHeader format orders.dat
–S DBARCH-LT2\SQL08DE01
–U sa –P xyz –f orders.fmt –c
The format file created looks like this:
10.0
27
1 SQLCHAR 0 12 ""\t"" 1 SalesOrderID """"
2 SQLCHAR 0 5 ""\t"" 2 RevisionNumber """"
3 SQLCHAR 0 24 ""\t"" 3 OrderDate """"
4 SQLCHAR 0 24 ""\t"" 4 DueDate """"
5 SQLCHAR 0 24 ""\t"" 5 ShipDate """"
6 SQLCHAR 0 5 ""\t"" 6 Status """"
7 SQLCHAR 0 3 ""\t"" 7 OnlineOrderFlag """"
8 SQLCHAR 0 50 ""\t"" 8 SalesOrderNumber SQL_...
9 SQLCHAR 0 50 ""\t"" 9 PurchaseOrderNumber SQL_...
10 SQLCHAR 0 30 ""\t"" 10 AccountNumber SQL_...
11 SQLCHAR 0 12 ""\t"" 11 CustomerID """"
12 SQLCHAR 0 12 ""\t"" 12 ContactID """"
13 SQLCHAR 0 12 ""\t"" 13 SalesPersonID """"
14 SQLCHAR 0 12 ""\t"" 14 TerritoryID """"
15 SQLCHAR 0 12 ""\t"" 15 BillToAddressID """"
16 SQLCHAR 0 12 ""\t"" 16 ShipToAddressID """"
17 SQLCHAR 0 12 ""\t"" 17 ShipMethodID """"
18 SQLCHAR 0 12 ""\t"" 18 CreditCardID """"
19 SQLCHAR 0 15 ""\t"" 19 CreditCardApprovalCode SQL_...
20 SQLCHAR 0 12 ""\t"" 20 CurrencyRateID """"
21 SQLCHAR 0 30 ""\t"" 21 SubTotal """"
22 SQLCHAR 0 30 ""\t"" 22 TaxAmt """"
23 SQLCHAR 0 30 ""\t"" 23 Freight """"
24 SQLCHAR 0 30 ""\t"" 24 TotalDue """"
25 SQLCHAR 0 256 ""\t"" 25 Comment SQL_...
26 SQLCHAR 0 37 ""\t"" 26 rowguid """"
27 SQLCHAR 0 24 ""\r\n"" 27 ModifiedDate """"
The first line shows the version of bcp.
The second line shows the number of columns.
The third line, first column shows the data field position.
The third line, second column shows the data type.
The third line, third column shows the prefix.
The third line, fourth column shows the data file field length.
The third line, fifth column shows the field or row terminator.
The third line, sixth column shows the column position.
The third line, seventh column shows the column name.
The third line, eighth column shows the column collation.
You get different
format files depending on your table and whether you chose character,
native, or Unicode as the data type. As you can see in the preceding
example, only the last two columns in the format file relate to the
actual table; the remaining columns specify properties of the data file.
