小编Shr*_*ath的帖子

我创建了2个表

CREATE TABLE table1(customerName VARCHAR(20),custid NUMBER ,order_id NUMBER ,price NUMBER );
CREATE TABLE table2(id NUMBER ,salary NUMBER );

现在,我尝试使用查询

SELECT t1.customername,t1.custid,t2.salary FROM table1 t1 left join table2 t2 ON t1.custid = t2.id;
SELECT t1.customername,t1.custid,t2.salary FROM table1 t1 left outer join table2 t2 ON t1.custid = t2.id;

但我得到了相同的输出.他们在工作中内部有什么区别吗？或者都是一样的!？

我正在学习游标,我无法打印中的布尔值

dbms_output.put_line();

代码是

DECLARE
CURSOR c_employees_3i is
SELECT * FROM employees_3i;
row_count BOOLEAN;
BEGIN
OPEN c_employees_3i;
row_count := c_employees_3i%isopen; 
Dbms_Output.put_line(bool_to_text(row_count));
CLOSE c_employees_3i;
END;

我收到这个错误

ORA-06550: line 8, column 22:
PLS-00201: identifier 'BOOL_TO_TEXT' must be declared
ORA-06550: line 8, column 1:
PL/SQL: Statement ignored

请帮我纠正错误.谢谢

我有以下代码,由于某种原因,永远不会到达文件的结尾,所以while循环永远不会结束.

public class Temp {
FileReader fr;

Temp() {
    try {
        fr = new FileReader("File path");
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    }
}

public static void main(String[] args) {
    Temp ob = new Temp();

    try {
        char c;
        while ((c = (char) ob.fr.read()) != -1) {
            System.out.println(c);
        }
        ob.fr.close();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

任何人都可以帮我解决这个问题!提前致谢 :)