How to get select to return a constant value?
BTW, it’s PostgreSQL 8.4. But I think the explicit CTE ( with…) is more readable (although that is always in the eyes of the beholder). This will return one row with all values having null except query_id if no row is found.
When to return distinct columns in table a?
Also note that we return DISTINCT a.*, because this will only return the columns for table a where the join criteria was met. Returning * would return the columns for both a and b where the criteria was met, and not including DISTINCT would result in a duplicate of each row for each time that row row matched another row more than once.
How to select rows with 2 columns equal value?
Question 2 : Select all rows in which C4 column has duplicates e.g. C4 has value 2 in row 3 and row 4, so select row 3 and 4. Actually this would go faster in most of cases: You join on different rows which have the same values.
When to return the blank row in select?
Will only return the “blank” row if the entire contents of “a” is null. i needed to do something similar and my brain was not giving, so i searched and found this question but then thought of this way also, if username is unique in players which in my use fits better (but surely it can be simplified more ?!
How to return a value if no rows are found?
SELECT CASE WHEN S.Id IS NULL THEN 0 ELSE S.Col1 END AS Col1, S.Col2, ISNULL (S.Col3, 0) AS Col3 FROM (SELECT @Id AS Id) R LEFT JOIN Sites S ON S.Id = R.Id AND S.Status = 1 AND This Might be one way. No record matched means no record returned. There’s no place for the “value” of 0 to go if no records are found.
What happens if the second Select returns nothing?
The second SELECT is only even executed if the first returns nothing. The data type of the NULL value is determined by the data type of tbl.id automatically. ANSI/ISO plans for LIMIT standardization?