Detect if value is number in MySQL
Is there a way to detect if a value is a number in a MySQL query? Such as SELECT * FROM myTable WHERE isANumber(col1) = true 15 Answers 15
where-clause
Left Join With Where Clause
I need to retrieve all default settings from the settings table but also grab the character setting if exists for x character. But this query is only retrieving those settings where character is = 1, not the default settings if the user havent setted anyone. SELECT `settings`.*, `character_settings`.`value` FROM (`settings`) LEFT JOIN `character_settings` ON `character_settings`.`setting_id` … Read more
SQL – HAVING vs. WHERE
I have the following two tables: 1. Lecturers (LectID, Fname, Lname, degree). 2. Lecturers_Specialization (LectID, Expertise). I want to find the lecturer with the most Specialization. When I try this, it is not working: SELECT L.LectID, Fname, Lname FROM Lecturers L, Lecturers_Specialization S WHERE L.LectID = S.LectID AND COUNT(S.Expertise) >= ALL (SELECT COUNT(Expertise) FROM Lecturers_Specialization … Read more
WHERE vs HAVING
Why do you need to place columns you create yourself (for example select 1 as “number”) after HAVING and not WHERE in MySQL? And are there any downsides instead of doing WHERE 1 (writing the whole definition instead of a column name)? 7 Answers 7
What is the difference between HAVING and WHERE in SQL?
What is the difference between HAVING and WHERE in an SQL SELECT statement? EDIT: I have marked Steven’s answer as the correct one as it contained the key bit of information on the link: When GROUP BY is not used, HAVING behaves like a WHERE clause The situation I had seen the WHERE in did … Read more
How to make “case-insensitive” query in Postgresql?
Is there any way to write case-insensitive queries in PostgreSQL, E.g. I want that following 3 queries return same result. SELECT id FROM groups where name=”administrator” SELECT id FROM groups where name=”ADMINISTRATOR” SELECT id FROM groups where name=”Administrator” 1Best Answer 11 Use LOWER function to convert the strings to lower case before comparing. Try this: … Read more
SQL JOIN – WHERE clause vs. ON clause
After reading it, this is not a duplicate of Explicit vs Implicit SQL Joins. The answer may be related (or even the same) but the question is different. What is the difference and what should go in each? If I understand the theory correctly, the query optimizer should be able to use both interchangeably. 2Best … Read more
