Update Data

UPDATE accounts SET balance = 900 WHERE id = 1;

// tx is a *sql.Tx from "database/sql"

transferAmount := 100
fromID := 1

if _, err := tx.Exec("UPDATE accounts SET balance = balance - $1 WHERE id = $2", transferAmount, fromID); err != nil {
    return err
}

// ds is an org.postgresql.ds.PGSimpleDataSource

int transferAmount = 100;
int fromID = 1;

try (Connection connection = ds.getConnection()) {
    connection.createStatement().executeUpdate("UPDATE accounts SET balance = balance - "
                                               + transferAmount + " where id = " + fromID);

} catch (SQLException e) {
    System.out.printf("sql state = [%s]\ncause = [%s]\nmessage = [%s]\n",
                      e.getSQLState(), e.getCause(), e.getMessage());
}

# conn is a psycopg2 connection

transferAmount = 100
fromID = 1

with conn.cursor() as cur:
    cur.execute("UPDATE accounts SET balance = balance - %s WHERE id = %s",
                (transferAmount, fromID));
conn.commit()