must appear in the GROUP BY clause or be used in an aggregate function

Yes, this is a common aggregation problem. Before SQL3 (1999), the selected fields must appear in the GROUP BY clause[*]. To workaround this issue, you must calculate the aggregate in a sub-query and then join it with itself to get the additional columns you’d need to show: But you may also use window functions, which looks simpler: The … Read more

MySQL: Invalid use of group function

You need to use HAVING, not WHERE. The difference is: the WHERE clause filters which rows MySQL selects. Then MySQL groups the rows together and aggregates the numbers for your COUNT function. HAVING is like WHERE, only it happens after the COUNT value has been computed, so it’ll work as you expect. Rewrite your subquery as:

Oracle SELECT TOP 10 records

You’ll need to put your current query in subquery as below : Oracle applies rownum to the result after it has been returned.You need to filter the result after it has been returned, so a subquery is required. You can also use RANK() function to get Top-N results. For performance try using NOT EXISTS in place of NOT IN. See this for more.

Update statement to update multiple rows

I have a question regarding the following syntax. Is there a cleaner way to roll this up into one statement rather than two. I’ve tried several iterations but this seems to be the only way I can successfully execute these two statements. I tried this as well and I also tried using an AND statement. … Read more

How do I limit the number of rows returned by an Oracle query after ordering?

Starting from Oracle 12c R1 (12.1), there is a row limiting clause. It does not use familiar LIMIT syntax, but it can do the job better with more options. You can find the full syntax here. (Also read more on how this works internally in Oracle in this answer). To answer the original question, here’s the query: (For earlier Oracle versions, please … Read more

mysql Foreign key constraint is incorrectly formed error

I ran into this same problem with HeidiSQL. The error you receive is very cryptic. My problem ended up being that the foreign key column and the referencing column were not of the same type or length. The foreign key column was SMALLINT(5) UNSIGNED and the referenced column was INT(10) UNSIGNED. Once I made them both the same … Read more

How do you trouble shoot a “Data type mismatch in criteria expression” error in MS Access 2010?

The criteria expression is the part of the query containing the conditions, as in WHERE <condition>. Look at those specifically. The error message means you’re comparing two things (this equals that, or this less than that, etc.) that are of two different, and incompatible types (comparing a number to a string, for example). You can find … Read more

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)