What about upgrading GROUP BY clause by use of useful commands? GROUP BY is used in a clause with aggregate operations. When it is used, aggregation happens throughout all...
SQL TRY CATCH command is designed to control code flow in case that error situation occurs (error handling). This construction consists of blocks. It is also possible to use...
Operator UNION ALL in SQL makes it possible to unify 2 query results and does not remove duplicities in queries. Operator returns records of both queries with no regard...
T-SQL command IF is used to control flow of code mainly in operations where we somehow influence db (DDL, DML operations) – for example procedures. You can mix it...
SQL CTE or so called Common table expression is simply put a temporary table (or better said it is a result set) in form of an expression. We can...
OVER clause can belong to commands working with so-called Window functions in SQL. These types of functions enable us to look at the data not only in their aggregated...
The order in which are the SQL clauses entered into the query are quite known. However, the order of logical query processing is different than in which we enter...
Loop is a repeated call of a part of a code with different parameters. Usually the code is bound to certain DML operation such as INSERT or UPDATE. We...
SQL Command INSERT is suitable for situations when we want to insert entries into the table. Insertion of rows can be done in multiple ways (further description below): You...
A trigger is a database object (procedure) that works as a watchdog for certain event. Using database triggers we can catch this event and initiate some additional action –...