updates to important

SQL/lessons/sql_3.md

@@ -1,13 +1,14 @@
 # PostGres - Advanced
 
 ## Lesson Objectives - important
-1. Joins
+
 1. Linking Tables
 1. Alias
 1. Indexes
 1. Constraints
 
 ## Lesson Objectives - good to know about
+
 1. EER Diagrams
 1. Unions
 1. Truncate
@@ -22,32 +23,21 @@
 
 ## Important
 
-### Joins
-1. Cross Join
-1. Inner Join
-1. Left Join
-1. Right Join
-1. Full Join
-```sql
-SELECT table1.column1, table2.column2
-FROM table1
-INNER JOIN table2
-ON table1.common_filed = table2.common_field;
-```
-
 ### Linking Tables
-1. `http://code.tutsplus.com/articles/sql-for-beginners-part-3-database-relationships--net-8561`
+
+1. [Some Nice Visuals](http://code.tutsplus.com/articles/sql-for-beginners-part-3-database-relationships--net-8561)
+1. One to Many/Many to One Relationships
+	- customer has many orders
 1. One to One Relationships
 	- each user has one address
 	- only one person at that address
-1. One to Many/Many to One Relationships
-	- customer has many orders
 1. Many to Many Relationships
 	- actors and movies
 1. Self Referncing Relationships
 	- customer referral
 
 ### Alias
+
 ```sql
 SELECT t1.column1 as col1, t2.column2 as col2
 FROM table1 as t1
@@ -56,14 +46,18 @@ ON t1.common_filed = t2.common_field;
 ```
 
 ### Indexes
+
 1. `CREATE INDEX index_name ON table_name (column_name);`
 1. `CREATE INDEX index_name ON table_name (column1_name, column2_name);`
+1. use `\d table_name` to view indexes
 1. Primary Key
 
 ### Constraints
+
 1. NOT NULL	
 1. Unique
 1. Foreign Keys
+
 ```sql
 CREATE TABLE companies(
   id          SERIAL       PRIMARY KEY,
@@ -77,6 +71,7 @@ CREATE TABLE people(
   email       VARCHAR(32)  NOT NULL UNIQUE,
   company_id  INT          REFERENCES companies(id)
 );
+INSERT INTO people (name, email, company_id) VALUES ('bob', 'bob@bob.com', 999)
 ```
 
 ## Good to Know About