[100% Off] Sql Practice Tests And Interview Questions, 120 Verified
Practice SQL for interviews and screening tests. Every answer key was produced by two SQL engines, not typed by hand.
What you’ll learn
- Predict what a SQL query returns
- which is what a screening test actually asks,Tell an inner join from a left join that a WHERE clause quietly turned into one,Handle NULL with confidence
- in comparisons
- in aggregates
- in IN and in NOT IN,Read window functions
- including partitions
- frames and the difference RANK makes,Write SQL that behaves the same on Postgres
- MySQL
- SQL Server
- Oracle and SQLite,See which of the seven blocks is costing you the marks
- block by block
Requirements
- You should be able to read a SELECT statement. Everything past that is explained,No installation needed. The tables are printed with every question,No vendor account
- no cloud database and no sample dataset to download
Description
This course contains the use of artificial intelligence.
Here is what that means in practice, and why it is the reason to take this one rather than another. Every question in these tests is built around a small set of tables and one query. When the test was assembled, that query was executed on two independent engines, SQLite and DuckDB, and the option marked correct is the result set they both returned. A question whose stated answer disagreed with the engines could not be published, the build refuses it. A query on which the two engines disagreed could not be published either, because that is a question about a dialect wearing the costume of a question about SQL. Those two checks are the whole point of the product.
If you have taken SQL practice tests before, you already know the two complaints. The answer key is wrong often enough that you stop trusting it, and half the questions turn out to be about one vendor’s engine even though the title said SQL. Neither can happen here. Each explanation ends with the exact result both engines returned, and any query the two of them answered differently was thrown out during the build rather than argued about in the reviews.
What is inside
Four full practice tests, 120 questions, forty-five minutes and a pass mark of 70 percent each.
Every question runs against one of three small tables you will get to know quickly, a shop with customers and orders, a company with departments and employees, and a table of exam marks. They are deliberately small, and they are deliberately awkward. There is an order whose customer does not exist, an employee with no department, a department with no employees, a mark that was never recorded and a pair of identical salaries. Those five rows are where the interesting questions live, because they are where real tables break real queries.
Questions are spread over seven blocks. Selecting, filtering and sorting. Joins, including the outer joins and the anti join. Grouping and aggregation. NULL, CASE and the set operators. Subqueries and common table expressions. Window functions. Strings, numbers and type conversion. Every question is tagged with its block, so the result screen tells you which one is costing you the marks instead of leaving you to guess.
Each answer, right or wrong, carries its own explanation. Not one comment for the question, one for every option, saying why that particular option is wrong and which confusion usually produces it.
What you will not find here
No question depends on which database you use at work. Nothing about PL/SQL, nothing about T-SQL, no vendor specific date function and no engine specific string function. If a query behaved differently on the two engines it was cut, which means what you learn here transfers to Postgres, MySQL, SQL Server, Oracle and SQLite alike.
You will also not find the same question twice. The build rejects a repeated query outright, which is the second thing reviewers on this shelf complain about.
How to use it
Sit a test under exam conditions first, forty-five minutes, no database open. Read every explanation afterwards, including the ones you got right, because guessing correctly and knowing are not the same thing. Then rerun the queries yourself. The tables fit in a screen and rebuild in a second on any engine you like.
Who this is for
Anyone facing a SQL screening test for a data analyst, data engineer, analytics or backend role, and anyone who writes SQL most weeks and suspects that a few of the habits are cargo cult. If you have ever been surprised by what NOT IN does when the subquery returns a NULL, or by a left join that silently turned into an inner join, this is aimed squarely at you.
