What are Aggregate Functions in SQL Server? The Books Online definition, the full list, and the NULL and GROUP BY rules that candidates often miss.
UNICODE: Supplementary Characters Depend on the Collation
UNICODE returns an integer for the first character, and supplementary-character support affects that integer. I make the collation explicit when interpreting those values. Otherwise the same visible input can produce a misleading comparison.
COALESCE Fallbacks: Empty Text Is Still a Supplied Value
COALESCE fallbacks keep empty text and spaces as supplied values. Apply an empty-value policy before choosing a display name.
Auditing Who Has sysadmin
Audit who has sysadmin in SQL Server, including direct members and Windows groups, then investigate nested access and forgotten logins.
SQL SERVER – What is – DML, DDL, DCL and TCL – Introduction and Examples
What are DML, DDL, DCL and TCL? A short introduction to the four groups of SQL commands, with examples like SELECT, CREATE, GRANT and COMMIT.
SQL SERVER – Time Out Due to Executing DELETE on Large RecordSet
Why does a DELETE on large recordset time out? When you want every row gone, use TRUNCATE instead, but keep in mind it resets the identity value.
Conditional COUNT: ELSE 0 Counts Nonmatching Rows
Conditional COUNT includes zero when CASE returns it. I compare an omitted ELSE with a zero branch before aggregating. A no-match group and an empty input expose the difference from SUM.