Java 如何检查 ResultSet 是否包含特定命名的字段？
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How to check that a ResultSet contains a specifically named field?
提问by Ivan
Having rs, an instance of java.sql.ResultSet, how to check that it contains a column named "theColumn"?
有了rsjava.sql.ResultSet 的一个实例，如何检查它是否包含名为“theColumn”的列？
采纳答案by Buhake Sindi
You can use ResultSetMetaDatato iterate through the ResultSet columns and see if the column name matches your specified column name.
您可以使用ResultSetMetaData遍历 ResultSet 列并查看列名是否与您指定的列名匹配。
Example:
例子：
ResultSetMetaData rsMetaData = rs.getMetaData();
int numberOfColumns = rsMetaData.getColumnCount();
// get the column names; column indexes start from 1
for (int i = 1; i < numberOfColumns + 1; i++) {
String columnName = rsMetaData.getColumnName(i);
// Get the name of the column's table name
if ("theColumn".equals(columnName)) {
System.out.println("Bingo!");
}
}
回答by Boris Pavlovi?
Try using the method ResultSet#findColumn(String)
尝试使用方法ResultSet#findColumn(String)
private boolean isThere(ResultSet rs, String column)
{
try
{
rs.findColumn(column);
return true;
} catch (SQLException sqlex)
{
logger.debug("column doesn't exist {}", column);
}
return false;
}
回答by Alois Cochard
You can do:
你可以做：
rs.findColumn("theColum")
and check for SQLException
并检查 SQLException
回答by darri
Use the ResultSetMetaDataobject provided by the ResultSetobject via rs.getMetaData()
使用对象提供的ResultSetMetaDataResultSet对象通过rs.getMetaData()
回答by madx
Use the ResultSetMetaDataclass.
使用ResultSetMetaData类。
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;
}
