MAX alias

Question

Just a small query.
Why is it that we need to have an alias for a MAX function to fetch the data
query = "SELECT MAX(changeLogID) AS CID " +
            "FROM ChangeLog " +
            "WHERE beforeUpdate like '%Status:Active%' " +
            "AND beforeUpdate like '%labID:" + labID + "%'";
stmt = conn.createStatement();
rs = stmt.executeQuery(query);
while(rs.next())
       System.out.println(rs.getInt("CID"));
}The above code works fine as I have an alias for MAX. However, the below code throws an error
query = "SELECT MAX(changeLogID) " +
            "FROM ChangeLog " +
            "WHERE beforeUpdate like '%Status:Active%' " +
            "AND beforeUpdate like '%labID:" + labID + "%'";
stmt = conn.createStatement();
rs = stmt.executeQuery(query);
while(rs.next())
       System.out.println(rs.getInt("changeLogID"));
java.sql.SQLException: Invalid column nameOracle:91

Answer 1

Pramukh wrote:
Just a small query.
Why is it that we need to have an alias for a MAX function to fetch the data
query = "SELECT MAX(changeLogID) AS CID " +
"FROM ChangeLog " +
"WHERE beforeUpdate like '%Status:Active%' " +
"AND beforeUpdate like '%labID:" + labID + "%'";
stmt = conn.createStatement();
rs = stmt.executeQuery(query);
while(rs.next())
System.out.println(rs.getInt("CID"));
}The above code works fine as I have an alias for MAX. However, the below code throws an error
query = "SELECT MAX(changeLogID) " +
"FROM ChangeLog " +
"WHERE beforeUpdate like '%Status:Active%' " +
"AND beforeUpdate like '%labID:" + labID + "%'";
stmt = conn.createStatement();
rs = stmt.executeQuery(query);
while(rs.next())
System.out.println(rs.getInt("changeLogID"));
java.sql.SQLException: Invalid column nameOracle:91changeLogID can be multiple where as Max(changeLogID) which is CID is only one. That is why you are getting en error.