＃1052-where子句中的“年”列不明确

Question

When I run this SQL will appear this error. #1052 - Column 'syear' in where clause is ambiguous . any one give me answer.

SELECT c.course_id
     , c.TITLE
     , c.SHORT_NAME
     , cs.overallmark 
  FROM courses c
     , course_subjects cs
 WHERE syear = '2010' 
   AND c.subject_id = cs.subject_id 
 ORDER 
    BY c.course_id
     , c.TITLE
     , c.SHORT_NAME
     , cs.overallmark

Answer 1

Your query should look something like this:

SELECT c.course_id, c.TITLE, c.SHORT_NAME, cs.overallmark 
FROM courses c JOIN
     course_subjects cs
     ON c.subject_id = cs.subject_id 
WHERE c.syear = 2010 
ORDER BY c.course_id, c.TITLE, c.SHORT_NAME, cs.overallmark;

Notes:

• Never use commas in the FROM clause. Always use proper, explicit JOIN syntax.
• Qualify all column names, especially when a query references more than one table.
• I assume that syear is stored as a number not a string. Do not put quotes around string constants.

Answer 2

You have a column named syear in both your tables and the DB engines does not know which one to pick.

Add the table name before it

course_subjects.syear

Besides that you should not use the old implicit join syntax any more.