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我在我準備好的語句中使用了MERGE
命令,當我在單線程環境中執行它時,它的工作正常,但是在多線程環境中,它會導致一些問題。即數據被複制,也就是說如果我有5個線程,每條記錄都會重複5次。我認爲db中沒有鎖定來幫助線程。 我的代碼:多線程編寫語句
//db:oracle
sb.append("MERGE INTO EMP_BONUS EB USING (SELECT 1 FROM DUAL) on (EB.EMP_id = ?) WHEN MATCHED THEN UPDATE SET TA =?,DA=?,TOTAL=?,MOTH=? WHEN NOT MATCHED THEN "+ "INSERT (EMP_ID, TA, DA, TOTAL, MOTH, NAME)VALUES(?,?,?,?,?,?) ");
//sql operation,calling from run() method
public void executeMerge(String threadName) throws Exception {
ConnectionPro cPro = new ConnectionPro();
Connection connE = cPro.getConection();
connE.setAutoCommit(false);
System.out.println(sb.toString());
System.out.println("Threadname="+threadName);
PreparedStatement pStmt= connE.prepareStatement(sb.toString());
try {
count = count + 1;
for (Employee employeeObj : employee) {//datalist of employee
pStmt.setInt(1, employeeObj.getEmp_id());
pStmt.setDouble(2, employeeObj.getSalary() * .10);
pStmt.setDouble(3, employeeObj.getSalary() * .05);
pStmt.setDouble(4, employeeObj.getSalary()
+ (employeeObj.getSalary() * .05)
+ (employeeObj.getSalary() * .10));
pStmt.setInt(5, count);
pStmt.setDouble(6, employeeObj.getEmp_id());
pStmt.setDouble(7, employeeObj.getSalary() * .10);
pStmt.setDouble(8, employeeObj.getSalary() * .05);
pStmt.setDouble(9, employeeObj.getSalary()
+ (employeeObj.getSalary() * .05)
+ (employeeObj.getSalary() * .10));
pStmt.setInt(10, count);
pStmt.setString(11, threadName);
// pStmt.executeUpdate();
pStmt.addBatch();
}
pStmt.executeBatch();
connE.commit();
} catch (Exception e) {
connE.rollback();
throw e;
} finally {
pStmt.close();
connE.close();
}
}
如果employee.size = 5,線程數= 5,執行後,我會得到25條記錄,而不是5
當我添加一個唯一的約束到我的表..它會導致錯誤,違反唯一的常量,所以我強制要壓制異常(只需趕上並繼續我的工作) – Anoop