Compound SQL Query
I have constructed this SQL query:
SELECT DISTINCT a.uid, a.sid, a.fname, a.lname, b.class_code from student a, class b where b.grade_code = '2' and a.class = b.class_code and a.school_code = 'SES' order by a.class, a.lname, a.fname
My attempt is to pick up all students in grade 2 for school SES. The grade field is not contained in the student table, rather the class field links to class_code in the class table.
The attached files are (File1), content of table class for all grade 2 classes, (File2) all students who are in grade 2 classes, (File3), partial result.
File4 is the structure of table student. File 5 is the structure of table class.
Note that class 31 in in grade 3, not grade 2.
What's wrong?
File1.jpg
File2.jpg
File3.jpg
File4.jpg
File5.jpg
SELECT DISTINCT a.uid, a.sid, a.fname, a.lname, b.class_code from student a, class b where b.grade_code = '2' and a.class = b.class_code and a.school_code = 'SES' order by a.class, a.lname, a.fname
My attempt is to pick up all students in grade 2 for school SES. The grade field is not contained in the student table, rather the class field links to class_code in the class table.
The attached files are (File1), content of table class for all grade 2 classes, (File2) all students who are in grade 2 classes, (File3), partial result.
File4 is the structure of table student. File 5 is the structure of table class.
Note that class 31 in in grade 3, not grade 2.
What's wrong?
File1.jpg
File2.jpg
File3.jpg
File4.jpg
File5.jpg
ASKER
To DonKronos:
It still picks up students in class 31 (a 3rd grade class).
See attached file (File6)
File6.jpg
It still picks up students in class 31 (a 3rd grade class).
See attached file (File6)
File6.jpg
Can you run this and post the result.
select distinct class_code
from class
where grade_code = '2' and class_code in (select class from student where school_code = 'SES')
ASKER
Hmmm ... doesn't seem logical.
Look in the class table and see what the grade_code is for class_code 31. I have a suspicion you will find grade_code = 2 for class_code = 31.
If that is not the case then I have to figure out how SQL server is joining rows that do not meet the specified criteria?
Look in the class table and see what the grade_code is for class_code 31. I have a suspicion you will find grade_code = 2 for class_code = 31.
If that is not the case then I have to figure out how SQL server is joining rows that do not meet the specified criteria?
ASKER
To all:
I did what DonKronos suggested (I had already confirmed that before I posted the original question). See attached (File 8).
I have the sinking feeling that it has to do with the fact that the name "class" is used as a column name in the table student and as a table name. I say this because I revised the original DonKronos query to eliminate the aliases & it falid saying something to the effect that "class" was not unique.
I hope I don't have to change the column name, it must be in 30 or 40 php scripts. Or the table name (even worse)
File8.jpg
I did what DonKronos suggested (I had already confirmed that before I posted the original question). See attached (File 8).
I have the sinking feeling that it has to do with the fact that the name "class" is used as a column name in the table student and as a table name. I say this because I revised the original DonKronos query to eliminate the aliases & it falid saying something to the effect that "class" was not unique.
I hope I don't have to change the column name, it must be in 30 or 40 php scripts. Or the table name (even worse)
File8.jpg
What i am trying to do is to know all the class_codes for school_code = 'SES' and grade_code = '2'
If the class code 31 has the grade_code = '2', then your query will return the records for that class code also.
select class_code
from class
where grade_code = '2' and class_code in (select class from student where school_code = 'SES')
group by class_code
or
select count(class_code)
from class
where grade_code = '2' and class_code in (21,22,31)
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ASKER
To Sharath_123:
I ran this query:
SELECT * from class where school_code = 'SES' and grade_code = '2'.
It produces the arrached File9. This says to me that there are EXACTLY 2 rows in the table that meet this criteria and the row with class_code = 31 is NOT one of them.
File9.jpg
I ran this query:
SELECT * from class where school_code = 'SES' and grade_code = '2'.
It produces the arrached File9. This says to me that there are EXACTLY 2 rows in the table that meet this criteria and the row with class_code = 31 is NOT one of them.
File9.jpg
ASKER
To To Sharath_123:
I ran this query:
Select * from class where class_code = 31 and grade_code = '2". I got the attached. But note that the school_code is NOT 'SES'.
Ah, I think I see the solution. I have to further qualify b (class) that b.school_code = 'SES'. I'll try that.
File10.jpg
I ran this query:
Select * from class where class_code = 31 and grade_code = '2". I got the attached. But note that the school_code is NOT 'SES'.
Ah, I think I see the solution. I have to further qualify b (class) that b.school_code = 'SES'. I'll try that.
File10.jpg
ASKER
The real solution is as I indicated in my last message, I had to add the FURTHER qualification "... and b.school_code = 'SES' ......"
You were most helpful & you led me in the right direction, so you get the points.
You were most helpful & you led me in the right direction, so you get the points.
from student a
inner join class b
on a.class = b.class_code and a.school_code = 'SES' and b.grade_code = '2'
order by a.class, a.lname, a.fname