PL/SQL表和列别名

Question

我想知道是否有像plsql中的表和列的别名。 我想要做这样的事情（伪）：

if (foo) 
then 
    alias bla_table = tablenameA 
    alias bla_column = coulmnnameA 
else 
    alias bla_table = tablenameB 
    alias bla_column = coulmnnameB 
end 

select bla_column from bla_table; 

Answer 1

有一些方法来归档类似的效果;可能最简单的方法是声明一个游标，并根据if路径将其打开以进行不同的查询。

例如，从Oracle Documentation采取：

CREATE PACKAGE emp_data AS 
    TYPE EmpCurTyp IS REF CURSOR RETURN emp%ROWTYPE; 
    PROCEDURE open_emp_cv (emp_cv IN OUT EmpCurTyp, choice IN INT); 
END emp_data; 

CREATE PACKAGE BODY emp_data AS 
    PROCEDURE open_emp_cv (emp_cv IN OUT EmpCurTyp, choice IN INT) IS 
    BEGIN 
     IF choice = 1 THEN 
     OPEN emp_cv FOR SELECT * FROM emp WHERE comm IS NOT NULL; 
     ELSIF choice = 2 THEN 
     OPEN emp_cv FOR SELECT * FROM emp WHERE sal > 2500; 
     ELSIF choice = 3 THEN 
     OPEN emp_cv FOR SELECT * FROM emp WHERE deptno = 20; 
     END IF; 
    END; 
END emp_data;