一个坑：java.sql.ResultSet.getInt==》the column value; if the value is SQL NULL, the value returned is 0

Retrieves the value of the designated column in the current row of this ​​ResultSet​​​ object as a ​​String​​ in the Java programming language.

Parameters:

columnLabel the label for the column specified with the SQL AS clause. If the SQL AS clause was not specified, then the label is the name of the column

Returns:

the column value; if the value is SQL ​​NULL​​​, the value returned is ​​null​​

Throws: SQLException  

int java.sql.ResultSet.getInt(String columnLabel) throws SQLException

Retrieves the value of the designated column in the current row of this ​​ResultSet​​​ object as an ​​int​​ in the Java programming language.

Parameters:

columnLabel the label for the column specified with the SQL AS clause. If the SQL AS clause was not specified, then the label is the name of the column

Returns:

the column value; if the value is SQL ​​NULL​​​, the value returned is ​​0​​

Throws: