Text was truncated or one or more characters had no match in the target code page.
You can fix with 2 steps;
- Increase your lenght of your data type from SQL database.
-  Or change the value of TypeGuessRows, use these steps:
On the Start menu, click Run. In the Run dialog box, type Regedt32, and then click OK.
Open the following key in the Registry editor:


Note For 64-bit systems, the corresponding key is as follows:

Double-click TypeGuessRows.
In the DWORD editor dialog box, click Decimal under Base. Type a value between 0 and 16, inclusive, for Value data.
Click OK, and then exit the Registry Editor.
A second way to work around this problem (without modifying the registry) is to make sure that rows with fields, which have data 255 characters or greater, are present in the first 8 rows of the source data file.
The valid range of values for the TypeGuessRows key is 0 to 16. However, if the value is 0, the number of source rows scanned is 16384. Keep in mind that a value of zero may cause a small performance hit if the source file is very large. 
Excel den SQL e veri aktarirken, eger asagidaki hatayi aliyorsaniz ;  
Text was truncated or one or more characters had no match in the target code page.
- SQL de tablodaki veri turu alanin boyutunu genisletin.(nvarchar(max))
Baslat Calistir "REGEDIT" 

Sisteminiz 64-bit ise:

TypeGuessRows= 0
yapin, tum satirlara bakacagi icin cok buyuk boyutlu dosyalarda bizraz beklersiniz o kadar. Bu sekilde excel den SQL e aktarim (import,transfer) yaparken sorun olusmayacak...