how to enforce a constraint in mysql?
By : user3142560
Date : March 29 2020, 07:55 AM
around this issue You could do it in your application code, but it's safest to do it in the database via a trigger. To prevent the insert from succeeding, generate an error in your trigger. We do something like this: code :
CREATE TRIGGER `t_insert`
BEFORE UPDATE ON `t`
FOR EACH ROW
BEGIN
IF new.A > new.B THEN
CALL NONEXISTENT_PROC()
END IF;
END

how to enforce constraint in sql?
By : Flanker Dai
Date : March 29 2020, 07:55 AM
this will help I have a question regarding enforce a constraint to my table. I have a table called workson and a table called staff, each staff has specific title(supervisor,authorizer,manager,...). I need to ensure that the supervisor and the authorizer cannot be the same staff on workson table.The cardinality between them is many to many. I am not sure how to do it. Can you please advise me to solve this problem? , Consider the following query code :
SELECT AssignmentNo, StaffNo
FROM worksOnStaff
WHERE StaffType = 'supervisor'
INTERSECT
SELECT AssignmentNo, StaffNo
FROM worksOnStaff
WHERE StaffType = 'authorizer'
CHECK ( NOT EXISTS ( SELECT AssignmentNo, StaffNo
FROM worksOnStaff
WHERE StaffType = 'supervisor'
INTERSECT
SELECT AssignmentNo, StaffNo
FROM worksOnStaff
WHERE StaffType = 'authorizer' ) );

SQL Constraint to Enforce Rule
By : Allan A. B. Thomsen
Date : March 29 2020, 07:55 AM
wish help you to fix your issue With eid as a primary key you won't be able to insert more than one row for any employee as that would violate the primary key constraint. So there's no way an employee could ever belong to more than one department the way your tables are modeled.

How to enforce a constraint between two points
By : Rob Bradshaw
Date : March 29 2020, 07:55 AM
I wish this helpful for you There is three issues in your code. First, you apply Euler integration for each constraint, but it should be applied only once at the end of each iteration. Second, The point p1 should be fixed. Third, you did not consider the mass in the force calculations. To fix it, add a force vector in the Point structure and use this code: code :
// Reset forces
p1.force = glm::vec3(0, 0, 0);
p2.force = glm::vec3(0, 0, 0);
// Add gravity
p1.force += gravity / p1.mass ;
p2.force += gravity / p2.mass ;
// Add spring forces
// To be put in applyConstraint, without dependency on dt
float k = 1 ;
glm::vec3 difference = p1.position  p2.position;
float current_length = glm::length(difference);
float original_length = glm::length(p2.op p1.op);
float displacement = (current_length  original_length) / current_length;
p1.force = k * displacement * difference ;
p2.force += k * displacement * difference ;
// Euler integration
p1.velocity += p1.force / p1.mass * dt ;
p2.velocity += p2.force / p2.mass * dt ;
//p1.position += p1.velocity * dt ; // This point is an anchor
p2.position += p2.velocity * dt ;

How do I enforce this constraint?
By : Ves0t
Date : March 29 2020, 07:55 AM
I hope this helps you . If I am reading you right, you have two constraints: Category Name + LogId must be unique; if LogId is null, Name must be unique. A given Category Name may be associated with a nonnull LogId, or a null LogId, but not both.

