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.
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.
SQL SERVER – List All Available TimeZone
sys.time_zone_info lists timezone names and their current offsets. My SQL Server 2019 environment returned 141 rows.