All Java developers not only must know “SQL”, but also a database is required for “JDBC tutorials”, “Hibernate Tutorials”, and so on. Any decent Java application will require a database. So, your self-taught Java projects must perform CRUD (i.e. Create Read, Update and Delete) operations on the database.
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SQL interview Questions & Answers is a must for any developer as all non-trivial applications need to talk to a database with CRUD operations. Q3 – Q15 are very popular with the interviewers. If you want to quickly practice your SQL skills try DB Fiddle or install MySQL locally as...
Q1. What is normalization? When to denormalize? A1. Normalization is a design technique that is widely used as a guide in designing relational databases. Normalization is essentially a two step process that puts data into tabular form by removing repeating groups and then removes duplicated data from the relational tables....
Q1 How will you go about identifying duplicate records in a table?
A1 The following SQL query will do the trick.
Note: Interviewer is testing if you understand that the aggregate queries need to have a “GROUP BY”
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Q. What are some of the considerations in auditing database table data? A. Creating audit tables without any constraints to store record changes. Audit tables are heavily hit with inserts, hence needs to have fewer indices if at all required. … Read more ›...
Common Table Expressions or CTE’s for short are used in SQL to simplify complex joins and subqueries, and to provide a means to query hierarchical data such as an organisational chart. This was also introduced in MySQL 8 – Using https://www.db-fiddle.com/. … Read more ›...
The following is a very popular SQL job interview question. Q. What is the difference between “Truncate” and “Delete” commands? A. TRUNCATE TABLE_NAME always locks the table and page but not each row, … Read more ›...
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