Question

I have the following problem:
I have two tables in one data base which consist of the same columns besides the name of the last column. I want to write data into them using Java.
I want to use the same preparedStatement for both tables, where I check with an if-command whether it is table1 or table2. table2 has amount10 as the name for the last column, table1 has amount20 for it. This number is stored in a variable within my code.

Below you can see a (simplified) example and how I tried to let the column name variable but it doesn’t work. Is there any way to fix this without copying the whole statement and manually changing the number variable?

String insertData = "INSERT INTO `database`.`"+table+"`
(`person_id`,`Date`,`amount`+"number") VALUES "+
"(?,?,?) ON DUPLICATE KEY UPDATE " +
"`person_id` = ? , " +
"`Date` = ? , " +
"`amount`+"number" = ? ; ";
PreparedStatement insertDataStmt;

Answer 1

This will not work since variables number and table are not going to be magically injected into your insertData string while you are changing them.
I’d to a method prepareInsertstatement(String table, String number) that would return correct PreparedStatement:

public void prepareInsertStatement(Connection conn, Strint table, String number) {
    String insertData = "INSERT INTO `database`.`"+table+"`
    (`person_id`,`Date`,`amount+"number"') VALUES "+
    "(?,?,?) ON DUPLICATE KEY UPDATE " +
    "`person_id` = ? , " +
    "`Date` = ? , " +
    "`amount+"number"' = ? ; ";
    PreparedStatement insertDataStmt = conn.prepareStatement(insertData);

    return insertDataStmt;
}

Just remember to close the PreparesStatement when you don’t need it any more.