A table has a composite index on (DistrictID, HireDate). Which query can use this index most effectively?
Une table possède un index composite sur (DistrictID, HireDate). Quelle requête peut l'utiliser le plus efficacement ?
Answers
AWHERE DistrictID = 12 AND HireDate >= '2024-01-01'WHERE DistrictID = 12 AND HireDate >= '2024-01-01'
BWHERE HireDate >= '2024-01-01' only, without any condition on DistrictIDWHERE HireDate >= '2024-01-01' seul, sans aucune condition sur DistrictID
CWHERE Salary > 500000WHERE Salary > 500000
DWHERE Name LIKE '%Jean%'WHERE Name LIKE '%Jean%'
The answer and explanation are in the full bank.
This question is one of 2,831 in the paid banks. Each comes with the correct answer and the reasoning behind it, not just a mark.
Unlock for 5,000 RWFMIFOTRA exam practicealigned to Practice set: Database Management·3 marks·Hard
More Database questions
- What is the main role of a database management system (DBMS) such as PostgreSQL, MySQL or SQL Server?
- In a relational table called Applicants, what does a single row represent?
- Which two properties must every primary key value have?
- The Employees table has a DistrictID column that must always refer to an existing row in the Districts table. What enforces this rule?
- An ExamResults table records one score per candidate per paper. Neither CandidateID nor PaperID is unique on its own. What is a suitable primary key?
- A designer gives each applicant an auto-generated ApplicantID as the primary key, and stores the national ID number as a separate unique column. Why use this surrogate key?
- One district has many sectors, and each sector belongs to exactly one district. What type of relationship is this?
- Each trainee can attend many courses, and each course has many trainees. How is this relationship stored in a relational database?