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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
1 cze 2021 · Use the || operator to concatenate two strings: SELECT 'Hi ' || 'there!'; -- result: Hi there! ||. Use this trick for numbers: Some databases implement non-standard solutions for concatenating strings like CONCAT() or CONCAT_WS(). Check the documentation for your specific database. Use the _ character to replace any single character.
This edition of SQL Practice Problems assumes that you have some basic background knowledge about relational databases and tables. However, I’ve added some beginner level questions to gradually introduce the various parts of the SQL Select statement for those with less experience in SQL.
22 paź 2024 · These exercises are designed to provide hands-on experience with common SQL tasks, from basic retrieval and filtering to more advanced concepts like joins window functions, and stored procedures. Practice SQL questions to enhance our skills in database querying and manipulation.
1 cze 2021 · Fetch all names that start with any letter followed by 'atherine': SELECT name FROM names WHERE name LIKE '_atherine'; Fetch all names that end with 'a': SELECT name FROM names WHERE name LIKE '%a'; USEFUL FUNCTIONS. Get the count of characters in a string: SELECT LENGTH('LearnSQL.com');-- result: 12 Convert all letters to lowercase: SELECT ...
29 lut 2024 · Practice basic SQL – writing SELECT queries, joining multiple tables, using aggregate functions, and working with GROUP BY – for free with these 18 beginner-friendly exercises. Solutions and explanations included!
Answer #1 You could use the SIGN() function in Sybase and other SQL products. This function returns -1, 0, or +1 if the argument is negative, zero, or positive, respectively. Assuming that your numbers are zero or greater, you simply write: SELECT * FROM MyTable WHERE SIGN(f1) + SIGN(f2) + ... + SIGN(f10) = 1; to find a single nonzero value.
