t-sql

Using DATEDIFF() with LEAD() to Calculate Time Until Future Events

by

When you’re analyzing how events unfold over time in a SQL database, one of the biggest challenges can be efficiently comparing what’s happening now to what comes next. Each event typically appears as its own row with a timestamp, but meaningful insight often comes from understanding how those timestamps relate to one another. Fortunately SQL Server provides some useful tools for this kind of sequential analysis.

Rather than relying on bulky self-joins or multi-step logic, SQL window functions offer a streamlined way to track these transitions. For example, by pairing the LEAD() function with DATEDIFF(), you can instantly measure the gap between consecutive events and surface insights that would otherwise require far more complex queries.

Read more

How to Unforce a Query Execution Plan in SQL Server

by

When you’ve forced an execution plan in SQL Server’s query store and later want to allow the optimizer to choose plans freely again, you’ll need to unforce the plan. You might want to do this because you’ve fixed the underlying issue or the forced plan is no longer optimal. Whatever the reason, the solution is straightforward and easy.

Read more

Generating Staggered Dates with SQL Server Window Functions

by

SQL Server’s window functions open up some creative possibilities when you need to work with dates. One interesting pattern involves pairing DATEADD() with ROW_NUMBER() to automatically generate sequential dates based on your query results.

This technique gives you a flexible way to calculate dates dynamically without hardcoding values or maintaining separate date tables. This can be useful for doing things like building a scheduling system, creating test data with realistic timestamps, or just spacing events across a timeline.

Read more

Building a Survey Results Dashboard in SQL

by

Survey data can be messy. You’ve got responses scattered across dozens or hundreds of rows, multiple choice answers, rating scales, and so on. And the challenge of turning all that raw data into something stakeholders can actually understand. A well-designed survey dashboard can transform those individual responses into a grid that shows patterns instantly. For example, which questions are getting strong agreement, where opinions diverge, and what trends emerge across different respondent groups.

Read more

Calculating Dynamic Date Offsets with Expressions in SQL Server’s DATEADD() Function

by

One of DATEADD()‘s less obvious features in SQL Server is its ability to accept expressions as the interval parameter rather than just simple numeric values. You can perform calculations, use arithmetic operations, or reference multiple columns right inside the function call. This gives you a more flexible way to calculate dates when the offset itself needs to be computed based on your data.

So, instead of adding or subtracting a fixed number of days, months, or years, you compute that number on the fly using whatever logic makes sense for your situation. Let’s look at an example that demonstrates this concept.

Read more