Write a SQL query using UNION ALL (not UNION) that uses the WHERE clause to eliminate duplicates. Why might you want to do this? View answer You can avoid duplicates using UNION ALL and still run much faster than UNION DISTINCT (which is actually same as UNION) by running a query like...
It also covers practice problems to help you understand the basic concepts of SQL. We've divided this article into the following sections: SQL Interview Questions PostgreSQL Interview Questions In the end, multiple-choice questions are provided to test your understanding. Play SQL...
SQL stands for Structured Query Language. It is used to maintain communication with a database. SQL is also considered a standard language for relational database management systems. A lot of relatable database management systems feature SQL. The following systems are Oracle, Microsoft SQL Server, ...
Free Practice Test Instructions: Choose your answer to the question and click "Continue" to see how you did. Then click 'Next Question' to answer the next question. When you have completed the free practice test, click 'View Results' to see your results. Good luck!
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The ON clause makes code easy to understand.17. The database designer has named the key (unique) columns from two tables differently.While joining these tables, which among the following will be the best practice?JOIN..ON Either NATURAL JOIN or JOIN...ON clauses Both A and B None of ...
50 SQL Query Questions Prepare Sample Data To Practice SQL Skills Sample Table – Worker WORKER_IDFIRST_NAMELAST_NAMESALARYJOINING_DATEDEPARTMENT 001 Monika Arora 100000 2021-02-20 09:00:00 HR 002 Niharika Verma 80000 2021-06-11 09:00:00 Admin 003 Vishal Singhal 300000 2021-02-20 09:00:...
When we execute a query and use theWHEREkeyword on a column that does not have an index, then the SQL Server has to do a full-table scan and check every row to find matches. This is a bad practice because it can be unpredictable in terms of execution time. Therefore this process may...
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The most feared part of the data analyst hiring process is the technical screening. Here are 3 SQL interview questions to practice in 2022.