Question

我对SQL不熟悉，并且此查询出现语法错误。我怀疑我可能错误地使用了'AS'关键字。谁能检查我的语法？我也尝试用[]代替单引号。谢谢！

SELECT m.dname, COUNT(*) AS 'Total Students', AVG(s.age) AS 'Average Age', 
AVG(s.gpa) AS 'Average GPA'
FROM student s JOIN major m
ON s.sid = m.sid
GROUP BY m.dname
HAVING COUNT(*) >= 3

编辑****

我得到的错误：

ERROR: syntax error at or near "'Total Students'" LINE 1: SELECT m.dname, COUNT(*) AS 'Total Students', AVG(s.age) AS... ^

使用PostgreSQL数据库

Answer 1

在postgres中，对于包含空格的列别名，请使用双引号，而不是单引号：

SELECT m.dname, COUNT(*) AS "Total Students", AVG(s.age) AS "Average Age", 
AVG(s.gpa) AS "Average GPA"
FROM student s JOIN major m
ON s.sid = m.sid
GROUP BY m.dname
HAVING COUNT(*) >= 3

- http://www.postgresql.org/docs/9.2/static/sql-select.html#SQL-SELECT-LIST

Answer 2

使用AS

时无需引号

试试这个

SELECT m.dname, COUNT(*) AS Total_Students, AVG(s.age) AS Average_Age, 
AVG(s.gpa) AS Average_GPA
FROM student s JOIN major m
ON s.sid = m.sid
GROUP BY m.dname
HAVING COUNT(*) >= 3

AS的SQL语法错误

2 个答案: