Join queries are not working as expected when trying to compare a count result with a value
I'm learnin SQL from a book and i'm trying to do some exercices on join queries.The only problem that i'm facing is that all of my join queries are not working while they seem well
students(student_id,student_names,student_age)
courses_students(course_id,student_id)
courses(course_id,course_schedule,course_room,teacher_id)
teachers(teacher_id,teacher_names)
The query is "which courses have more than 5 students enrolled?"
Here is what i've done :select course_name,count(select count(*) from courses) as count from students,courses,courses_students where students.student_id=courses_students.student_id,courses.course_id=courses_students.course_id and count > 5
And the other one is what are the names of students enrolled in at least 2 courses scheduled for the same hours
My query :select student_name,schedule from students,courses,courses_students where students.student_id=courses_students.student_id,courses.course_id=courses_students.course_id and count > 2
mysql join query
asked 10 mins ago
jochri3jochri3
101
New contributor
jochri3 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |
I'm learnin SQL from a book and i'm trying to do some exercices on join queries.The only problem that i'm facing is that all of my join queries are not working while they seem well
students(student_id,student_names,student_age)
courses_students(course_id,student_id)
courses(course_id,course_schedule,course_room,teacher_id)
teachers(teacher_id,teacher_names)
The query is "which courses have more than 5 students enrolled?"
Here is what i've done :select course_name,count(select count(*) from courses) as count from students,courses,courses_students where students.student_id=courses_students.student_id,courses.course_id=courses_students.course_id and count > 5
And the other one is what are the names of students enrolled in at least 2 courses scheduled for the same hours
My query :select student_name,schedule from students,courses,courses_students where students.student_id=courses_students.student_id,courses.course_id=courses_students.course_id and count > 2
mysql join query
asked 10 mins ago
jochri3jochri3
101
New contributor
jochri3 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |
I'm learnin SQL from a book and i'm trying to do some exercices on join queries.The only problem that i'm facing is that all of my join queries are not working while they seem well
students(student_id,student_names,student_age)
courses_students(course_id,student_id)
courses(course_id,course_schedule,course_room,teacher_id)
teachers(teacher_id,teacher_names)
The query is "which courses have more than 5 students enrolled?"
Here is what i've done :select course_name,count(select count(*) from courses) as count from students,courses,courses_students where students.student_id=courses_students.student_id,courses.course_id=courses_students.course_id and count > 5
And the other one is what are the names of students enrolled in at least 2 courses scheduled for the same hours
My query :select student_name,schedule from students,courses,courses_students where students.student_id=courses_students.student_id,courses.course_id=courses_students.course_id and count > 2
mysql join query
asked 10 mins ago
jochri3jochri3
101
New contributor
jochri3 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
I'm learnin SQL from a book and i'm trying to do some exercices on join queries.The only problem that i'm facing is that all of my join queries are not working while they seem well
students(student_id,student_names,student_age)
courses_students(course_id,student_id)
courses(course_id,course_schedule,course_room,teacher_id)
teachers(teacher_id,teacher_names)
The query is "which courses have more than 5 students enrolled?"
Here is what i've done :select course_name,count(select count(*) from courses) as count from students,courses,courses_students where students.student_id=courses_students.student_id,courses.course_id=courses_students.course_id and count > 5
And the other one is what are the names of students enrolled in at least 2 courses scheduled for the same hours
My query :select student_name,schedule from students,courses,courses_students where students.student_id=courses_students.student_id,courses.course_id=courses_students.course_id and count > 2
mysql join query
mysql join query
asked 10 mins ago
jochri3jochri3
101
New contributor
jochri3 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 10 mins ago
jochri3jochri3
101
New contributor
jochri3 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 10 mins ago
jochri3jochri3
101
New contributor
jochri3 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 10 mins ago
jochri3jochri3
101
asked 10 mins ago
jochri3jochri3
101
101
New contributor
jochri3 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
jochri3 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
jochri3 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |
add a comment |
0
active
oldest
votes
Your Answer
StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "182"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);
StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});
function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: false,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: null,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});
}
});
jochri3 is a new contributor. Be nice, and check out our Code of Conduct.
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fdba.stackexchange.com%2fquestions%2f228317%2fjoin-queries-are-not-working-as-expected-when-trying-to-compare-a-count-result-w%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
0
active
oldest
votes
0
active
oldest
votes
active
oldest
votes
active
oldest
votes
jochri3 is a new contributor. Be nice, and check out our Code of Conduct.
jochri3 is a new contributor. Be nice, and check out our Code of Conduct.
jochri3 is a new contributor. Be nice, and check out our Code of Conduct.
jochri3 is a new contributor. Be nice, and check out our Code of Conduct.
Thanks for contributing an answer to Database Administrators Stack Exchange!
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
To learn more, see our tips on writing great answers.
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fdba.stackexchange.com%2fquestions%2f228317%2fjoin-queries-are-not-working-as-expected-when-trying-to-compare-a-count-result-w%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
