In this example, we tried to illustrate commit on nested transactions. Using a SELECT query we can check that two rows have been created corresponding to the employee id 10031 and 10034. Code: select * from employees; Output: Example #5 SQL program to illustrate the use of COMMIT command o...
This simple question is hard to answer in SQL: "Show me the name and salary of the employee who has the highest salary in each department, as well as the total salary for that person's department." Broken into two separate queries, this question poses no problem. Here is the first pa...
Oracle SQL Oracle supports all standard joins and provides unique options likeNATURAL JOIN, which automatically joins tables based on matching column names. Oracle’s support for hierarchical queries withCONNECT BYcan sometimes reduce the need for additional joins by handling nested data more efficiently...
In my early years as a junior SQL Server DBA, one of the things I struggled with was filtering data when writing queries. I was told many times not to use SELECT * to return all columns and rows in a production database. I know I only want specific columns and rows returned. Sure, ...
SETDATEFIRST1-- first day of the week is a MondayIF(DATEPART(WEEKDAY,GETDATE())=1)BEGINSELECT'Monday'ENDELSEBEGINSELECT'Not a Monday'END For the remainder of the tip, example T-SQL queries are run onthe AdventureWorks2017 sample database. At every section, the syntax is given, so you...
1. Nested Sub-Query A nested sub-query is like the example provided in the previous section. Here, there is no dependency between the outer and inner queries (sub-query). The sub-query will be executed first and only once, and then the main query will be executed using the results from...
Examples of Substring in SQL Let us now delve into the working functionalities of substrings in SQL. We would look at how substrings could be used in literals, conditional tables, and nested queries. Using Substring on Literals While utilizing the function SUBSTRING() in SQL, we obtain the ...
Nested Queries ^ A very powerful feature of SQL: a WHERE clause can itself contain an SQL query! (Actually, so can FROM and HAVING clauses.) ^ To find sailors who’ve not reserved #103, use NOT IN ^ To understand semantics of nested queries, think of a^ nested loops ...
1. TPC-H data structure IN & EXISTS are common yet hard-to-handle to SQL. We are often con ..
The SQL LEAD function and SQL LAG function can be very useful for finding data in your result set and simplifying your queries. Learn all about them in this article. Get All Of My SQL Cheat Sheets Get The Cheat Sheets Table of Contents ...