Add Marc Wilson SQL cheat sheet

Author: ktaranov

README.md

@@ -443,14 +443,15 @@ Useful links, scripts, tools and best practice for Microsoft SQL Server Database
  - [Azure updates](https://azure.microsoft.com/en-us/updates/?status=all)
  - [Guides for Microsoft SQL Server Express](https://expressdb.io/) (by John McCall)
  - [SQL Server Diagrams](http://www.e-squillace.com/tech/techdiagrams/#SQL_Server)
- - [SQL Cheat Sheet](https://websitesetup.org/sql-cheat-sheet/) (by Luke Harrison)
+ - [SQL Cheat Sheet for MySQL](https://websitesetup.org/sql-cheat-sheet/) (by Luke Harrison)
  - [Azure Database Migration Guide](https://datamigration.microsoft.com/) (by Microsoft)
  - [Hermitage: Testing transaction isolation levels in relation databases](https://github.com/ept/hermitage) (by Martin Kleppmann)
  - [csv to INSERT online converter - translates your tab-delimited data into a T-SQL INSERT statement](https://table.strd.co/) (by Structured Concepts AB)
  - [SQL Server Diagrams](http://www.e-squillace.com/techdiagrams-sqlserver/) (by George Squillace)
  - [New Stars of Data 2020 Presentations](https://github.com/SQLGrillen/NSOD-1) (by SQLGrillen)
  - [Get Your ColumnScore](https://columnscore.com) (by ColumnScore)
  - [SQL Assessment API rules in .csv format](https://github.com/microsoft/sql-server-samples/blob/master/samples/manage/sql-assessment-api/DefaultRuleset.csv) (by Microsoft)
+ - [SQL cheat sheet for PostgreSQL and Oracle](https://www.pcwdld.com/sql-cheat-sheet) (by Marc Wilson)
 
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