An int column turns 01234 into 1234 and never gives the zero back. Here is how to fix the column, and how to repair old rows without guessing.
tempdb-Heavy Queries: Finding Them in Query Store
The tempdb spike is over before you log in. Query Store remembers who caused it, and here is how to ask.
Scalar Subqueries: An Empty Input Produces NULL
Scalar subqueries contribute one value to an outer row. Keep row absence separate from a present NULL and enforce the at-most-one-row contract.
Cached Plan Reuse: How to Tell if a Query Used a Cached Plan
Cached plan reuse is invisible in a result set. This post shows three checks on SQL Server: the compiled and runtime parameter values in the plan, the usecounts column of the plan cache, and the plan creation time.
Login Database Access: List the Databases a Login Can Open
Check login database access by matching the login SID against the users of every online database. One query shows the user, the CONNECT state and the guest back door, and it needs no impersonation.
Get Current Time Zone – SQL in Sixty Seconds #187
Lots of people often ask me how to get the current time zone in SQL Server when I am working on Comprehensive Database Performance Health Check.
Detecting Memory Pressure – SQL in Sixty Seconds #186
After my video on CPU running 100%, many of you asked for one on memory. Here is my SQL in Sixty Seconds video on detecting memory pressure.
MySQL – Wait For Seconds Using SELECT SLEEP()
For a WAIT FOR test in MySQL, I use SLEEP with a bounded delay. A customer asked for the corresponding command.
Parquet Exports From SQL Server 2022 With CETAS
Build Parquet exports from SQL Server 2022 with PolyBase CETAS, S3-compatible storage, and checks for rows, types, and files.
IGNORE NULLS in SQL Server 2022: Carrying the Last Known Value Forward
Use IGNORE NULLS for forward-filled readings, find the next known value, and compare the older running-count grouping method carefully.