Question

I am trying to build a dynamic sql query in java (shown below)

    sqlStr = "Select * " +
        "from " + tableName

    if(tableName!=null){
        if(tableName.equals("Table1"){
            sqlStr = sqlStr.concat("order by city desc");
        }else if(tableName.equals("Table2"){
            sqlStr = sqlStr.concat("order by country desc");
        }else if(tableName.equals("Table3"){
            sqlStr = sqlStr.concat("order by price desc");
        }
    }

Now what i would like to do is to add a final ‘else’ statement which would order the query based on whether the table contains a column named ‘custID’. There will be several tables with that column so i want to sort the ones that have that column by custID. (Rather than having hundreds of additional if statements for each table that does have that column name.) Is this possible? i have seen people using the ‘decode’ function but i cant work out how to use it here.

Answer 1

Use DatabaseMetaData to get the table information.

You can use the getTablexxx() and getColumnxx() methods to get the table information.

Connection conn = DriverManager.getConnection(.....);
DatabaseMetaData dbmd = conn.getMetaData();
dbmd.getxxxx(); 

Note: you forgot space in your code before ORDER BY clause.