Code reviewHardcr-g204

Subject Transaction isolationLevel Senior–Staff~28 minCommon in Databases & SQL interviewsIndustries Software development

Question

Review this Java (JDBC) reconciliation routine that asserts debits equal credits.

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Code to reviewjava

1void reconcile(Connection conn, long batchId) throws SQLException {2    conn.setAutoCommit(false);3    long debits = scalar(conn,4        "SELECT COALESCE(SUM(amount),0) FROM ledger "5        + "WHERE batch_id = ? AND kind = 'D'", batchId);6    long credits = scalar(conn,7        "SELECT COALESCE(SUM(amount),0) FROM ledger "8        + "WHERE batch_id = ? AND kind = 'C'", batchId);9    if (debits != credits) {10        alert("Imbalance in batch " + batchId);11    }12    conn.commit();13}

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