SQL错误ORA-00923:未在预期位置找到FROM关键字

Question

SELECT Person_ID, CONCAT('First_name','Surname') AS "Person_Name", Next_of_kin, '~ No next of kin ~' AS Next_of_kin_name, Next_of_kin_age AS NULL  
FROM PERSON  
WHERE Next_of_kin IS NULL
UNION
SELECT Childs.Person_ID, CONCAT('Childs.First_name','Childs.Surname') AS "Person_name", Next_of_kin, CONCAT('Fathers.First_name','Fathers.Surname') AS "Next_of_kin_name",TO_CHAR(sysdate, 'YYYY') - TO_CHAR(Fathers.birth_date, 'YYYY')
(TO_CHAR(sysdate, 'YYYY')- TO_CHAR(Birth_date, 'YYYY')) AS Next_of_kin_age 
FROM Person Childs, Person Fathers
WHERE Childs.next_of_kin = Fathers.Person_ID
AND TO_CHAR(sysdate, 'YYYY') - TO_CHAR(Fathers.birth_date, 'YYYY') >= 50;

Answer 1

• 上一个列名作为NULL返回，但实际上您希望返回值作为Next_of_kin_age.

的NULL

• 还有，在第二个select的最后一列中，你遗漏了运算符，我假设是减运算符。

作为Next_of_kin_age的TO_CHAR(sysdate，'YYYY')- TO_CHAR(Fathers.birth_date，'YYYY') (TO_CHAR(sysdate，'YYYY') - TO_CHAR(Birth_date，'YYYY'))

尝尝这个

SELECT Person_ID, 
       CONCAT('First_name','Surname') AS "Person_Name", 
       Next_of_kin, 
       '~ No next of kin ~' AS Next_of_kin_name, 
       NULL AS Next_of_kin_age 
FROM PERSON  
WHERE Next_of_kin IS NULL
UNION
SELECT Childs.Person_ID, 
       CONCAT('Childs.First_name','Childs.Surname') AS "Person_name", 
       Next_of_kin, 
       CONCAT('Fathers.First_name','Fathers.Surname') AS "Next_of_kin_name",
       TO_CHAR(sysdate, 'YYYY') - TO_CHAR(Fathers.birth_date, 'YYYY') - (TO_CHAR(sysdate, 'YYYY') - TO_CHAR(Birth_date, 'YYYY')) AS Next_of_kin_age 
FROM Person Childs, Person Fathers
WHERE Childs.next_of_kin = Fathers.Person_ID
AND TO_CHAR(sysdate, 'YYYY') - TO_CHAR(Fathers.birth_date, 'YYYY') >= 50;