Copying a virtual machine from one host to another
This post will explain the process of copying a virtual machine instance from one host computer to another using Oracle’s VM VirtualBox with Windows 7.
You have an error in your SQL syntax
One of the most common problems I come across is users not being able to resolve a basic SQL syntax error thrown in MySQL. You have an error in your SQL syntax; check the manual that corresponds to your MySQL… Continue Reading
Why can’t I use my aliased column in the WHERE clause?
A query will fail when a column is aliased and then referenced in the WHERE clause. SELECT col1, col2 AS c2 FROM tbl1 WHERE c2 BETWEEN 2 AND 6SELECT col1, col2 AS c2 FROM tbl1 WHERE c2 BETWEEN 2 AND… Continue Reading
Sorting software versions
There may be a time where a software version is stored as a string. In order to sort it, it will need to be broken up into its individual parts (major, minor, patch and build) and then sorted.
NULL behavior in three valued logic
SQL uses three valued logic (true, false, or unknown). This is important when dealing with NULL as a query may not return the desired results.
Temporary tables and table variables in SQL Server
I will briefly explain the differences between temporary tables and table variables. Temporary Tables (#) CREATE TABLE #temp (col1 …)CREATE TABLE #temp (col1 …) Table Variables (@) DECLARE @temp TABLE (col1 …)DECLARE @temp TABLE (col1 …) What do the signs… Continue Reading
Rows to column header using dynamic T-SQL
There may be instances where you need to prepare columns for a SELECT statement or for a SELECT … PIVOT.
Running total
This post will show an example of how to join a table against itself to return a running total.
Last second of future date
The following query is useful when trying to select an inclusive range of records using DATETIME. For this example, we will use GETDATE() which returns the current date & time. You can modify this at any instance in the code… Continue Reading
Split comma separated name (last, first)
The following example will return two columns (first name, last name) based on a single, concatenated, comma separated name. table —— name —— Chin, Cheryl Frank, Robert SELECT RIGHT([name], LEN([name]) – CHARINDEX(’,’, [name]) – 1) AS [first], LEFT([name], CHARINDEX(’,’, [name])-1)… Continue Reading