问题描述
由于ResultSet包含从动态SQL返回的数据，是否有任何方法可以确定ResultSet是否包含特定的列名？例如，如果我运行 rs.getString（Column_ABC）; 但是Column_ABC实际上不存在，它将抛出异常。如何测试ResultSet是否可以从名为Column_ABC的列中获取数据？
As the ResultSet contains the data returned from the dynamic SQL, if there are any method to determine if the ResultSet contains a particular column name ? For example , if I run rs.getString("Column_ABC"); but Column_ABC does not really exist, it will throw out the exception . How can I test if the ResultSet can get a data from a column named "Column_ABC" ?
推荐答案
使用 ResultSetMetaData 类。
Use the ResultSetMetaData class.
public static boolean hasColumn(ResultSet rs, String columnName) throws SQLException {
ResultSetMetaData rsmd = rs.getMetaData();
int columns = rsmd.getColumnCount();
for (int x = 1; x <= columns; x++) {
if (columnName.equals(rsmd.getColumnName(x))) {
return true;
}
}
return false;
}
我不明白的是为什么需要这个功能。正在执行的查询或存储过程应具有已知结果。应该知道查询的列。需要这样的功能可能表明某处存在设计问题。
The thing I don't understand is why this function would ever be needed. The query or stored procedure being executed should have known results. The columns of the query should be known. Needing a function like this may be a sign that there is a design problem somewhere.
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