When combining multiple query blocks in MySQL, we can use the INTERSECT clause to return just those rows that are common to both query blocks.
It’s a bit like the UNION clause, except that it excludes rows that aren’t present in both queries.
Tag: create query
2 Ways to Rename the Columns when using VALUES to Create a Constant Table in PostgreSQL
When we use the VALUES statement to create a constant table, PostgreSQL automatically names the columns column1, column2, etc. This saves us from having to provide names for the columns or from getting a blank column header.
But we also have the option of naming the columns ourselves.
Continue readingHow to Rename the Columns Returned by the VALUES Statement in SQLite
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 readingUsing VALUES instead of SELECT in SQLite
Some 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 readingHow to use VALUES as a Stand Alone SQL Statement in PostgreSQL
Many 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.
Using VALUES as a Stand Alone Statement in MySQL
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.
Creating Named Windows in SQL Server with the WINDOW Clause
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 readingCapping a Value at a Fixed Amount in SQL Server
The 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 readingFind Out Which Numeric Column Has the Highest Value in SQL Server
If 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.
3 Ways to Remove Duplicate Rows from Query Results in SQL
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.
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