I have to make a 'query' method for my class which accesses MySQL thru' JDBC.
The input parameter to the method is a full SQL command (with values included), so I don't know the names of columns to fetch out.
Some of the columns are strings, some others are integers, etc.
The method needs to return the value of type ArrayList<HashMap<String,Object>>
where each HashMap is 1 row, and the ArrayList contains all rows of result.
I'm thinking of using ResultSet.getMetaData().getColumnCount()
to get the number of columns then fetch cell by cell out of the current row, but is this the only solution? any better ones?
I have the example code here, just in case anybody need it. ('Con' in the code is the standard JDBC connection).
//query a full sql command
public static ArrayList<HashMap<String,Object>>
rawQuery(String fullCommand) {
try {
//create statement
Statement stm = null;
stm = con.createStatement();
//query
ResultSet result = null;
boolean returningRows = stm.execute(fullCommand);
if (returningRows)
result = stm.getResultSet();
else
return new ArrayList<HashMap<String,Object>>();
//get metadata
ResultSetMetaData meta = null;
meta = result.getMetaData();
//get column names
int colCount = meta.getColumnCount();
ArrayList<String> cols = new ArrayList<String>();
for (int index=1; index<=Col_Count; index++)
cols.add(meta.getColumnName(index));
//fetch out rows
ArrayList<HashMap<String,Object>> rows =
new ArrayList<HashMap<String,Object>>();
while (result.next()) {
HashMap<String,Object> row = new HashMap<String,Object>();
for (String colName:cols) {
Object val = Result.getObject(colName);
row.put(colName,val);
}
rows.add(row);
}
//close statement
stm.close();
//pass back rows
return tows;
}
catch (Exception ex) {
System.out.print(ex.getMessage());
return new ArrayList<HashMap<String,Object>>();
}
}//raw_query
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