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Function coalesce(column_1, column_2, ...) takes two or more arguments (columns or other values like strings, numbers) and return first non-NULL argument. Principle of work: check if first argument is NULL. if yes, go to the next step, otherwise return the argument
Practical SQL, 2nd Edition is a beginner-friendly guide to the database programming language SQL. Author Anthony DeBarros starts with beginner SQL concepts such as queries, data types, and basic math and aggregation, and then works through intermediate and advanced topics including statistics, cleaning data, GIS, and automating tasks.
1 cze 2021 · Standard SQL Functions Cheat Sheet. TEXT FUNCTIONS. CONCATENATION. Use the || operator to concatenate two strings: SELECT 'Hi ' || 'there!'; -- result: Hi there! Remember that you can concatenate only character strings using. ||. Use this trick for numbers: SELECT '' || 4 || 2;
SQL Window Functions Cheat Sheet. WINDOW FUNCTIONS. Window functions compute their result based on a sliding window frame, a set of rows that are somehow related to the current row. AGGREGATE FUNCTIONS VS. WINDOW FUNCTIONS. Unlike aggregate functions, window functions do not collapse rows. current row. SYNTAX. SELECT city, month, SUM(sold) OVER (
22 paź 2024 · By tackling these problems, you'll solidify your understanding of advanced SQL concepts like joins, subqueries, functions, and window functions, ultimately boosting your ability to work with real-world data scenarios effectively.
1 cze 2021 · Standard SQL Functions Cheat Sheet. TEXT FUNCTIONS. CONCATENATION. Use the || operator to concatenate two strings: SELECT 'Hi ' || 'there!'; -- result: Hi there! Remember that you can concatenate only character strings using ||. Use this trick for numbers: SELECT '' || 4 || 2; -- result: 42.
SELECT P3.proc_id, MAX(ConcurrentProcs.tally) FROM (SELECT P1.anest_name, P1.start_time, COUNT(*) FROM Procs AS P1 INNER JOIN Procs AS P2 ON P1.anest_name= P2.anest AND P2.start_time P1.start_time GROUP BY P1.anest_name, P1.start_time) AS ConcurrentProcs(anest_name, start_time, tally) INNER JOIN Procs AS P3 ON ConcurrentProcs.anest_name= P3 ...
