When the field imported into the database in Excel is greater than 255, the field in the first row is extended by more than 255.

When the field imported into the database in Excel is greater than 255, the field in the first row is extended by more than 255.

Because the Excel driver will pre-sample some data to determine the Data Type of the field during the import operation, the judgment on the sample data result is different from the Data Type of all data: 1. If the data type of a column field is different, the import result is null, for example, numeric value and text. If the sample data only contains text, the value record is null after being imported; 2. The length of a text field in a column is different, causing the field length to be intercepted: The driver determines the text length of the sample data. If the length does not exceed 255, it is defined as 255 nvarchar, therefore, if a record with a length greater than 255 exists in the data outside sampling, the length will be truncated to 255, and information will be lost.