Getting started with SQL SELECT JOIN Example Databases and Tables UPDATE Indexes CREATE TABLE UNION / UNION ALL ALTER TABLE CASE INSERT Primary Keys ORDER BY GROUP BY Filter results using WHERE and HAVING Window Functions Common Table Expressions Views LIKE operator Functions (Aggregate)DELETE String Functions Data Types AND & OR Operators Triggers TRUNCATE MERGE Foreign Keys Finding Duplicates on a Column Subset with Detail Sequence Comments Subqueries Execution blocks Stored Procedures DROP Table Row number Transactions CREATE FUNCTION SQL Group By vs Distinct Table Design cross apply, outer apply Synonyms CREATE Database SKIP TAKE (Pagination)EXPLAIN and DESCRIBE Information Schema IN clause NULL SQL Injection Cascading Delete Order of Execution DROP or DELETE Database EXCEPT TRY/CATCH XML GRANT and REVOKE Functions (Scalar/Single Row)Relational Algebra EXISTS CLAUSE Materialized Views Functions (Analytic)SQL CURSOR Identifier Clean Code in SQL

Comments

Single-line comments

Single line comments are preceded by --, and go until the end of the line:

SELECT *
FROM Employees -- this is a comment
WHERE FName = 'John'

Multi-line comments

Multi-line code comments are wrapped in /* ... */:

/* This query
   returns all employees */
SELECT *
FROM Employees

It is also possible to insert such a comment into the middle of a line:

SELECT /* all columns: */ *
FROM Employees

Contributors

Topic Id: 1597

Example Ids: 5179,5180

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