In SQL Server, the OPENQUERY rowset function enables you to execute a pass-through query on a linked server.
OPENQUERY is commonly referenced in the FROM clause of a query as if it were a table, but it can also be referenced as the target table of an INSERT, UPDATE, or DELETE statement.
This article presents an example of using OPENQUERY to do an UPDATE pass-through query.
In MongoDB, the $orderBy query modifier sorts the results of a query in ascending or descending order.
$orderBy accepts a document that specifies the field to sort, and the sort order. The sort order can be either 1 for ascending or -1 for descending.
$orderBy has been deprecated in the mongo shell since v3.2. Use the cursor.sort() method instead.
In SQL Server, there are a few ways to get metadata of the result set from a query. This includes the data type of the columns returned by a T-SQL query.
In particular, the sys.dm_exec_describe_first_result_set system dynamic management function is a good choice for such a task.
In MongoDB, the $nin query operator selects the documents where the field’s value is not in the specified array or where the field doesn’t exist.
In MongoDB, the $in query operator selects the documents where the value of a field equals any value in the specified array.
The $in query operator is not to be confused with the $in aggregation pipeline operator, which returns a boolean indicating whether a specified value is in the array.
In SQL, you can join three tables or more by adding another join after the first one.
You can also run nested joins by specifying one join as the join condition for another.
Continue readingIf you ever find yourself in the situation where you’re about to execute a stored procedure, but you suddenly catch yourself. You wonder “How many columns does this thing return? Which tables? Does it query a remote server?”
The good news is there are several ways to get this information before you run the query. Let’s look at them.
Continue readingA LEFT SEMI JOIN is kind of a half-join. It returns any distinct values that are returned by both the query on the left and right sides of the query.
However, when using T-SQL in SQL Server, if you try to explicitly use LEFT SEMI JOIN in your query, you’ll probably get the following error:
A LEFT ANTI SEMI JOIN is a type of join that returns only those distinct rows in the left rowset that have no matching row in the right rowset.
But when using T-SQL in SQL Server, if you try to explicitly use LEFT ANTI SEMI JOIN in your query, you’ll probably get the following error:
In SQL, the UNION clause concatenates the results of two queries into a single result set.
You can use the UNION clause with or without the ALL argument:
UNION ALL – Includes duplicates.UNION – Excludes duplicates.Some RDBMSs also accept UNION DISTINCT, which is the equivalent to UNION. That is, it excludes duplicates.
Below are some basic examples to demonstrate how it works.
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