Added cheatsheet for Week 1.

SQL-CHEATSHEET.md

@@ -0,0 +1,45 @@
+# SQL Cheatsheet
+
+## Queries
+
+### Specify what information to extract
+
+```sql
+SELECT column
+```
+
+## From which table
+
+```sql
+FROM table
+```
+
+## Only extract rows where the condition holds
+
+(Used with an operator: `>, <, >=, <=, =, <>, BETWEEN, LIKE, IN`)
+```sql
+WHERE column = 'value'
+```
+
+## Combining `WHERE` clauses:
+
+(Used with: `AND, OR`)
+```sql
+WHERE column = 'value' OR
+      column = 'other value'
+```
+
+## Aggregating results:
+
+(Used with: `SUM, COUNT, MIN, MAX, AVG`)
+```sql
+SELECT SUM(column)
+FROM table
+```
+
+## Aliasing tables
+
+```sql
+SELECT column AS alias
+FROM table
+```