How do I create a custom sort in SQL?
Now we have developed the sql query to get custom order result of country in given order.
- SELECT * FROM TBL_Country.
- ORDER BY CASE WHEN name = ‘INDIA’ THEN 1.
- WHEN name = ‘PAKISTAN’ THEN 2.
- WHEN name = ‘CHINA’ THEN 3.
- WHEN name = ‘GERMANY’ THEN 4.
- WHEN name = ‘FRANCE’ THEN 5.
- ELSE (ROW_NUMBER() OVER (ORDER BY name)+5) END ASC.
How do I sort a specific order in SQL?
In SQL ORDER BY clause, we need to define ascending or descending order in which result needs to be sorted.
- ASC: We can specify ASC to sort the result in ascending order.
- DESC: We can specify DESC to sort the result in descending order.
How do I sort a value in SQL?
The ORDER BY statement in sql is used to sort the fetched data in either ascending or descending according to one or more columns.
- By default ORDER BY sorts the data in ascending order.
- We can use the keyword DESC to sort the data in descending order and the keyword ASC to sort in ascending order.
What’s the best way to store sort order in SQL?
A better choice if you can get them to buy off on it, is to allow them to sort the data by columns (desc or asc). Usually the user interface can be designed so that if you click on a column header, it will resort the data by that column. This is relatively straightforward to do and meets most needs for custom ordering.
How do I store a list of tables in SQL?
No, there is no “better” way to store a sequence of items in a single column. Relational databases are designed specifically to store one value per row/column combination. In order to store more than one value, you must serialize your list into a single value for storage, then deserialize it upon retrieval.
Is SQL order by expensive?
The duration and resource (CPU and memory) consumption of the sort operation will change depending on the number of rows to be sorted. In this context, we can easily say that sorting operation is very costly for the SQL Server when it works for a huge number of rows.
Is SQL order by slow?
When a specific order is required, SQL Server must test every row. For example, to place rows in name order, it must sort all rows by name. This will be slow if there are a lot of rows, and no index to provide that order without sorting.
How do I make an order faster?
- Use Indexes.
- Modify/Update filesort algorithm.
- Make sure columns use only the smallest amount of space required.
- Have lots of space available in the temporary directory.
How can I make a group faster?
Let’s analyze it step by step:
- Scan each row of table a which has 1310720 rows.
- Join each row of table a with b, c and d – this means that each of the 1310720 rows will be joined, making the temporary table bigger.
- Execute the group by which will scan again the 1310720 rows and creating the result data set.
Does indexing speed up group by?
Not likely. GROUP BY and ORDER BY typically entail a sort. However, in this case a HashAggregate is used (likely because we’re working with the whole table). And, it takes more time 655ms compared to the previous 611ms.
Which is faster distinct or group by in SQL Server?
With 500 000 records in HSQLDB with all distinct business keys, the performance of DISTINCT is now better – 3 seconds, vs GROUP BY which took around 9 seconds.
Which is more efficient group by or distinct?
In MySQL, DISTINCT seems a bit faster than GROUP BY if theField is not indexed. DISTINCT only eliminate duplicate rows but GROUP BY seems to sort them in addition.
Should I use distinct or group by?
DISTINCT is used to filter unique records out of the records that satisfy the query criteria. The “GROUP BY” clause is used when you need to group the data and it should be used to apply aggregate operators to each group.
How do you remove duplicates without using distinct in SQL?
Below are alternate solutions :
- Remove Duplicates Using Row_Number. WITH CTE (Col1, Col2, Col3, DuplicateCount) AS ( SELECT Col1, Col2, Col3, ROW_NUMBER() OVER(PARTITION BY Col1, Col2, Col3 ORDER BY Col1) AS DuplicateCount FROM MyTable ) SELECT * from CTE Where DuplicateCount = 1.
- Remove Duplicates using group By.
How do you make a column unique?
Set column as unique in SQL Server from the GUI:
- Open SQL Server Management Studio.
- Right click your Table, click “Design”.
- Right click the column you want to edit, a popup menu appears, click Indexes/Keys.
- Click the “Add” Button.
- Expand the “General” tab.