SQL Primer vs SQL Code Play

1970 E.F. Codd has started a revolution with his paper 'A relational model of data for large shared data banks, Communications of the ACM, Volume 13, Issue 6 (June 1970)' that finally led to the today's omnipresent database query language SQL. This little app shows some primitive and derived operations with the following information: * SQL92 and SQL86/89 sample queries, * the results of the queries and * appropriate descriptions. Furthermore the SQL test script that has been used for the calculation of the samples can be displayed. The app is interesting for the first contact with the database subject and for all who are using SQL86/89 queries for over two decades now and finally want to change to SQL92 also ;)

Turn a SQL example into something you can explore. SQL Code Play gives you a local query workspace, guided lessons and focused challenges in one app. Read how a statement works, run it against sample tables and change it to see how the answer changes. A workspace for hands-on learning The Code and Output tabs keep the statement and its result close together. Edit your query, tap Run and examine the returned table. Row and column counts provide context, NULL values are marked, and messages distinguish an empty result from a completed statement or a query error. Undo and redo help you work through changes in the editor. You can begin with the supplied database instead of building sample data first. Employee, meeting and room records provide material for filtering, grouping and joining tables. The database list displays table names and record counts. Tapping a table loads a SELECT statement so you can inspect the data and decide what to try next. Restore lets you rebuild the sample database after experiments. Lessons that connect reading with doing Search the tutorial collection or filter it by fundamentals, filtering, analysis and advanced topics. Lesson details explain the purpose of an example, describe its logic and offer practice tips. Send the example to SQL Workspace, modify it and review the output. Local viewed and practiced indicators help you distinguish topics you have read from examples you have tried. Work through selection, conditions, ordering and aliases, then explore joins, aggregate functions and grouped summaries. Examples also cover creating tables, changing records, constraints, subqueries and transactions. When you are ready to go further, investigate common table expressions, window functions, date calculations and JSON operations. You can return to a specific topic whenever you need a reminder. Three ways to practise SQL Lab offers a sequence of query templates that open directly in the workspace. Explore tasks such as ranking salaries, summarising departments, finding duplicates and selecting high-value products. The templates give you a statement to study and adapt. Choose the Best Answer turns SQL syntax into focused multiple-choice questions. Select the missing piece, check your answer and consult a hint or explanation when you need help. Fill in the Blanks asks you to complete queries with the correct tokens, reinforcing the placement of keywords, operators and clauses. Challenge progress is kept locally, and the activities show the levels or missions available to you. Use the learning path that fits your session Begin with a tutorial if a concept is new. Choose a short challenge to review a detail. Open a lab template when you want to spend more time exploring a query. This combination suits students learning databases, people starting SQL and developers revisiting familiar syntax. The core query workspace and bundled lessons run locally without a cloud database account. Online services such as ads, purchases and support links may require connectivity. Practice database changes are for learning; Restore resets the sample data. Select system, light or dark appearance from Settings to match your preferred reading environment. The app contains advertising and offers an optional subscription to remove ads. Build your understanding through a simple cycle: read the explanation, edit the statement, run it and inspect the result. Terms of Use https://www.apple.com/legal/internet-services/itunes/dev/stdeula/