If you’ve ever used the VALUES clause as a stand alone statement, you may have noticed that SQLite provides default column names for the results. SQLite conveniently names them column1, column2, and so on.
However as convenient as this is, you might want to provide names that are more meaningful.
Fortunately there’s an easy way to do that.
Continue readingSome database management systems, including SQLite, allow us to use the VALUES keyword as a stand alone SQL statement. So we can use VALUES to return a constant table, usually with less code than would be required if we were to use the SELECT statement.
The following examples demonstrate how.
Continue readingMany of us who work with SQL databases have used the VALUES keyword with the INSERT statement when inserting data into a database.
But perhaps a lesser known fact is that some RDBMSs allow us to use VALUES as a stand alone SQL statement. PostgreSQL is one such RDBMS.
When used as a stand alone statement, we can use a VALUES statement instead of a SELECT statement.
MySQL 8.0.19 introduced the VALUES DML statement, which is a table constructor that can be used as a stand alone SQL statement.
This is not to be confused with the VALUES keyword that’s used with the INSERT or REPLACE statements when inserting data (although it can be used for that purpose too). It also shouldn’t be confused with the VALUES() function that’s used with INSERT … ON DUPLICATE KEY UPDATE statements.
Many RDBMSs support the concept of named windows – windows that we can reference from within an OVER clause when defining a window function.
For those of us using SQL Server, we had to wait until the release of SQL Server 2022 before we could create named windows for our window functions. But with the release of SQL Server 2022, we now have the option of using named windows in our window functions.
Continue readingThe introduction of the LEAST() and GREATEST() functions in SQL Server 2022 were a welcome addition. These functions enable us to get the minimum or maximum value from a list of values. There are plenty of use cases for these functions.
One such use case is to provide a cap on the values returned by a query.
Continue readingIf you have a query that returns multiple columns with numeric values in SQL Server, you can pass them to the GREATEST() function to find out which column has the highest value.
Sometimes when we run a SQL query, we only want to see unique rows. But depending on the columns we’re selecting, we might end up with duplicate rows. And this could happen without even knowing it, especially with large data sets.
But it doesn’t have to be this way.
Fortunately most SQL databases provide us with an easy way to remove duplicates.
Continue readingThe SQL COUNT() function is a handy tool for telling us how many rows would be returned in a query. We can pass a column name to the function or we can pass the asterisk (*) wildcard to indicate all columns.
If a column contains NULL values, we could get different results, depending on whether we use the column name or the asterisk (*).
The SQL UNION operator concatenates the results of two queries into a single result set. By default it returns distinct rows (i.e. it removes any redundant duplicate rows from the result set). But we can also use UNION ALL to return non-distinct rows (i.e. retain duplicates).
When it comes to NULL values, it’s pretty straight forward. SQL treats two NULL values as non distinct values. In other words, they’re duplicates.
Continue reading