I have 3 tables course, grade and evaluation. I want comparing two tables grade and evaluation . if the data in the table grade does not exist in the table evaluation , then the data will appear (output)

" select Grade.ID_Courses,Course.ID_Courses,Grade.NAME,
Course.NAME, Grade.ID_Courses,
Evaluation.NAME,
Evaluation.Year,
Grade.Year
from Grade, Course, Evaluation
WHERE
Grade.ID_Courses=Course.ID_Courses AND
Grade.NAME=JOHN and
Grade.Year=1 and
Evaluation.NAME=GRADE.NAME and
Grade.ID_Courses NOT IN (SELECT ID_Courses FROM Evaluation where NAME=JOHN and Year=1 )
GROUP BY Grade.ID_Courses"
the problem is when the name john is not in the table evaluation then there is no output comes out .
0 answers
Hot tools Tags
Hot Questions
Popular tool
vc9-vc14 (32+64 bit) runtime library collection (link below)
Download the collection of runtime libraries required for phpStudy installation
VC9 32-bit
VC9 32-bit phpstudy integrated installation environment runtime library
PHP programmer toolbox full version
Programmer Toolbox v1.0 PHP Integrated Environment
VC11 32-bit
VC11 32-bit phpstudy integrated installation environment runtime library
SublimeText3 Chinese version
Chinese version, very easy to use
Hot Topics
20522
7
13634
4






