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I have a table that has a processed_timestamp column -- if a record has been processed then that field contains the datetime it was processed, otherwise it is null.
I want to write a query that returns two rows:
NULL xx -- count of records with null timestamps NOT NULL yy -- count of records with non-null timestamps Is that possible?
Update: The table is quite large, so efficiency is important. I could just run two queries to calculate each total separately, but I want to avoid hitting the table twice if I can avoid it.
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All rows with a NULL in the column are treated as if NULL was another value. If a grouping column contains null values, all null values are considered equal, and they are put into a single group. Show activity on this post. Group By groups all the records with NULL values.
ORDER BY and GROUP BY with NULL SQL considers the NULL values as the UNKNOWN values. Therefore, if we use ORDER By and GROUP by clause with NULL value columns, it treats them equally and sorts, group them. For example, in our customer table, we have NULLs in the MilddleName column.
Inside the stored procedure, the parameter value is first tested for Null using the ISNULL function and then checked whether it is Blank (Empty). If the parameter has value then only matching records will be returned, while if the parameter is Null or Blank (Empty) then all records from the table will be returned.
In MySQL you could do something like
SELECT IF(ISNULL(processed_timestamp), 'NULL', 'NOT NULL') as myfield, COUNT(*) FROM mytable GROUP BY myfield In T-SQL (MS SQL Server), this works:
SELECT CASE WHEN Field IS NULL THEN 'NULL' ELSE 'NOT NULL' END FieldContent, COUNT(*) FieldCount FROM TheTable GROUP BY CASE WHEN Field IS NULL THEN 'NULL' ELSE 'NOT NULL' END If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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